Displaying publications 1 - 20 of 25 in total

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  1. Variations in oil palm (Elaeis guineensis Jacq.) progeny response to high aluminium concentrations in solution culture
    Cristancho RJ, Hanafi MM, Omar SR, Rafii MY
    Plant Biol (Stuttg), 2011 Mar;13(2):333-42.
    PMID: 21309980 DOI: 10.1111/j.1438-8677.2010.00378.x
    Aluminium (Al) phytotoxicity is an important soil constraint that limits crop yield. The objectives of this study were to investigate how growth, physiology, nutrient content and organic acid concentration is affected by Al, and to assess the degree of Al tolerance in different oil palm progeny (OPP). Four OPPs ['A' (Angola dura × Angola dura), 'B' (Nigerian dura × Nigerian dura), 'C' (Deli dura × AVROS pisifera) and 'D' (Deli dura × Dumpy AVROS pisifera)] were grown in different Al concentrations (0, 100 and 200 μm) in aerated Hoagland solution, pH 4.4, for 80 days. We observed a severe reduction (57.5%) in shoot dry weight, and root tips were reduced by 46.5% in 200 μm Al. In 'B' and 'C', the majority of macro- and micronutrients in plants were reduced significantly by 200 μm Al, with Mg being lowered by more than 50% in roots and shoots. The 200 μm Al treatment resulted in a 56.50% reduction in total leaf area, a 20% reduction in net photosynthesis and a 17% reduction in SPAD chlorophyll value in the third leaf. Root tips (0-5 mm) showed a significant increase in oxalic acid content with increasing Al concentration (∼ 5.86-fold); progeny 'A' had the highest concentration of oxalic acid. There was a significant interaction between Al concentration × OPP on total leaf number, root volume, lateral root length, Mg and K in root and shoot tissues, and Ca and N in shoots. The OPPs could be ranked in their tolerance to Al as: 'A' > 'D' > 'B' > 'C'.
    Matched MeSH terms: Plant Roots/growth & development
  2. Fulltext The effect of tillage systems on phosphorus distribution and forms in rhizosphere and non-rhizosphere soil under maize (Zea mays L.) in Northeast China
    Xomphoutheb T, Jiao S, Guo X, Mabagala FS, Sui B, Wang H, et al.
    Sci Rep, 2020 04 20;10(1):6574.
    PMID: 32313140 DOI: 10.1038/s41598-020-63567-7
    An appropriate tillage method must be implemented by maize growers to improve phosphorus dynamics in the soil in order to increase phosphorus uptake by plant. The objective of this study was to investigate the effects of tillage systems on phosphorus and its fractions in rhizosphere and non-rhizosphere soils under maize. An experimental field was established, with phosphate fertilizers applied to four treatment plots: continuous rotary tillage (CR), continuous no-tillage (CN), plowing-rotary tillage (PR), and plowing-no tillage (PN). Under the different tillage methods, the available P was increased in the non-rhizosphere region. However, the concentration of available P was reduced in the rhizosphere soil region. The soil available P decreased with the age of the crop until the maize reached physiological maturity. The non-rhizosphere region had 132.9%, 82.5%, 259.8%, and 148.4% more available P than the rhizosphere region under the CR, PR, CN, and PN treatments, respectively. The continuous no-tillage method (CN) improved the uptake of soil phosphate by maize. The concentrations of Ca2-P, Ca8-P, Fe-P, Al-P and O-P at the maturity stage were significantly lower than other seedling stages. However, there was no significant relationship between total P and the P fractions. Therefore, a continuous no-tillage method (CN) can be used by farmers to improve phosphorus availability for spring maize. Soil management practices minimizing soil disturbance can be used to impove phosphorus availability for maize roots, increase alkaline phosphatase activity in the rhizosphere soil and increase the abundance of different phosphorus fractions.
    Matched MeSH terms: Plant Roots/growth & development
  3. Fulltext The allometry of coarse root biomass: log-transformed linear regression or nonlinear regression?
    Lai J, Yang B, Lin D, Kerkhoff AJ, Ma K
    PLoS One, 2013;8(10):e77007.
    PMID: 24116197 DOI: 10.1371/journal.pone.0077007
    Precise estimation of root biomass is important for understanding carbon stocks and dynamics in forests. Traditionally, biomass estimates are based on allometric scaling relationships between stem diameter and coarse root biomass calculated using linear regression (LR) on log-transformed data. Recently, it has been suggested that nonlinear regression (NLR) is a preferable fitting method for scaling relationships. But while this claim has been contested on both theoretical and empirical grounds, and statistical methods have been developed to aid in choosing between the two methods in particular cases, few studies have examined the ramifications of erroneously applying NLR. Here, we use direct measurements of 159 trees belonging to three locally dominant species in east China to compare the LR and NLR models of diameter-root biomass allometry. We then contrast model predictions by estimating stand coarse root biomass based on census data from the nearby 24-ha Gutianshan forest plot and by testing the ability of the models to predict known root biomass values measured on multiple tropical species at the Pasoh Forest Reserve in Malaysia. Based on likelihood estimates for model error distributions, as well as the accuracy of extrapolative predictions, we find that LR on log-transformed data is superior to NLR for fitting diameter-root biomass scaling models. More importantly, inappropriately using NLR leads to grossly inaccurate stand biomass estimates, especially for stands dominated by smaller trees.
    Matched MeSH terms: Plant Roots/growth & development*
  4. The PAL2 promoter activities in relation to structural development and adaptation in Arabidopsis thaliana
    Wong JH, Namasivayam P, Abdullah MP
    Planta, 2012 Feb;235(2):267-77.
    PMID: 21874349 DOI: 10.1007/s00425-011-1506-9
    Phenylalanine ammonia lyase (PAL) plays a major role in plant growth, development and adaptation. In Arabidopsis thaliana, the enzyme is encoded by four genes, namely PAL1, PAL2, PAL3, and PAL4 with PAL1 and PAL2 being closely related phylogenetically and functionally. PAL1 promoter activities are associated with plant development and are inducible by various stress agents. However, PAL2 promoter activities have not been functionally analysed. Here, we show that the PAL2 promoter activities are associated with the structural development of a plant and its organs. This function was inducible in an organ-specific manner by the avirulent strain of Pseudomonas syringae pv. tomato (JL1065). The PAL2 promoter was active throughout the course of the plant development particularly in the root, rosette leaf, and inflorescence stem that provide the plant with structural support. In aerial organs, the levels of PAL2 promoter activities were negatively correlated with relative positions of the organs to the rosette leaves. The promoter was inducible in the root following an inoculation by JL1065 in the leaf suggesting PAL2 to be part of an induced defence system. Our results demonstrate how the PAL2 promoter activities are being coordinated and synchronised for the structural development of the plant and its organs based on the developmental programme. Under certain stress conditions the activity may be induced in favour of certain organs.
    Matched MeSH terms: Plant Roots/growth & development
  5. Role of phosphate solubilizing bacteria on rock phosphate solubility and growth of aerobic rice
    Panhwar QA, Radziah O, Zaharah AR, Sariah M, Razi IM
    J Environ Biol, 2011 Sep;32(5):607-12.
    PMID: 22319876
    Use of phosphate-solubilizing bacteria (PSB) as inoculants has concurrently increased phosphorous uptake in plants and improved yields in several crop species. The ability of PSB to improve growth of aerobic rice (Oryza sativa L.) through enhanced phosphorus (P) uptake from Christmas island rock phosphate (RP) was studied in glasshouse experiments. Two isolated PSB strains; Bacillus spp. PSB9 and PSB16, were evaluated with RP treatments at 0, 30 and 60 kg ha(-1). Surface sterilized seeds of aerobic rice were planted in plastic pots containing 3 kg soil and the effect of treatments incorporated at planting were observed over 60 days of growth. The isolated PSB strains (PSB9 and PSB16) solubilized significantly high amounts of P (20.05-24.08 mg kg(-1)) compared to non-inoculated (19-23.10 mg kg(-1)) treatments. Significantly higher P solubilization (24.08 mg kg(-1)) and plant P uptake (5.31 mg plant(-1)) was observed with the PSB16 strain at the highest P level of 60 kg ha(-1). The higher amounts of soluble P in the soil solution increased P uptake in plants and resulted in higher plant biomass (21.48 g plant(-1)). PSB strains also increased plant height (80 cm) and improved root morphology in aerobic rice. The results showed that inoculation of aerobic rice with PSB improved phosphate solubilizing activity of incorporated RP.
    Matched MeSH terms: Plant Roots/growth & development
  6. Fulltext Role of accumulated calcium in alleviating aluminum injury in wheat plants
    Hossain MA, Ashrafuzzaman M, Hossain AK, Ismail MR, Koyama H
    ScientificWorldJournal, 2014;2014:457187.
    PMID: 24701169 DOI: 10.1155/2014/457187
    Aluminum (Al) sensitive wheat cultivar kalyansona was grown for 14 d in a range of Ca solution (125, 625, and 2500 μM) plus other nutrients without Al. At 14 d after Ca treatment, half of these plants were harvested (H1), and the rest of the plants were exposed to 100 μM Al for additional 6 d and harvested (H2). Severe Al injury was found only in the plants with the lowest supply of Ca before Al treatment. Aluminum concentration in the apoplastic fluid was very high at 125 μM Ca probably because the plasma membrane of some of the cells was destroyed due to the attack of 100 μM Al. Aluminum content in roots decreased with increasing supply of Ca before Al treatment. Calcium content decreased drastically at harvest (H2) in the plants with 100 μM Al. Under Al stress conditions, the plant responded to Al in different ways due to not only the different Ca supply but also the variation of Ca content in the plant tissues. Actually, the plants having the largest Ca content in the roots before Al treatment can receive less Al injury during Al treatment. To substantiate this idea, a companion study was conducted to investigate the effects of 2500 μM Ca supply during, before, and after 100 μM Al treatment on root growth. The results indicated clearly that exogenous Ca supply before Al treatment is able to alleviate Al injury but less effective than Ca supply during Al treatment.
    Matched MeSH terms: Plant Roots/growth & development*
  7. Fulltext Rhizodegradation of Petroleum Oily Sludge-contaminated Soil Using Cajanus cajan Increases the Diversity of Soil Microbial Community
    Allamin IA, Halmi MIE, Yasid NA, Ahmad SA, Abdullah SRS, Shukor Y
    Sci Rep, 2020 Mar 05;10(1):4094.
    PMID: 32139706 DOI: 10.1038/s41598-020-60668-1
    Most components of petroleum oily sludge (POS) are toxic, mutagenic and cancer-causing. Often bioremediation using microorganisms is hindered by the toxicity of POS. Under this circumstance, phytoremediation is the main option as it can overcome the toxicity of POS. Cajanus cajan a legume plant, was evaluated as a phyto-remediating agent for petroleum oily sludge-spiked soil. Culture dependent and independent methods were used to determine the rhizosphere microorganisms' composition. Degradation rates were estimated gravimetrically. The population of total heterotrophic bacteria (THRB) was significantly higher in the uncontaminated soil compared to the contaminated rhizosphere soil with C. cajan, but the population of hydrocarbon-utilizing bacteria (HUB) was higher in the contaminated rhizosphere soil. The results show that for 1 to 3% oily sludge concentrations, an increase in microbial counts for all treatments from day 0 to 90 d was observed with the contaminated rhizosphere CR showing the highest significant increase (p  plant. The composition and taxonomic analysis of microbiota-amplified sequences were categorized into eight phyla for the contaminated non-rhizosphere and ten phyla for the contaminated rhizosphere. The overall bacterial composition of the two treatments varied, as the distribution shows a similar variation between the two treatments in the phylum distribution. The percentage removal of total petroleum hydrocarbon (TPH) after 90 days of treatments with 1, 2, 3, 4, and 5% (w/w) of POS were 92, 90, 89, 68.3 and 47.3%, respectively, indicating removal inhibition at higher POS concentrations. As the search for more eco-friendly and sustainable remediating green plant continues, C. cajan shows great potential in reclaiming POS contaminated soil. Our findings will provide solutions to POS polluted soils and subsequent re-vegetation.
    Matched MeSH terms: Plant Roots/growth & development
  8. Relative salinity tolerance of warm season turfgrass species
    Uddin KM, Juraimi AS, Ismail MR, Othman R, Rahim AA
    J Environ Biol, 2011 May;32(3):309-12.
    PMID: 22167942
    Fresh water, coupled with soil salinization in many areas has resulted in an increased need forscreening of salt tolerant turf grasses. Relative salinity tolerance of eightwarm season turfgrass species were examined in this study in sand culture. Grasses were grown in a glasshouse, irrigated with either distilled water or saline sea water adjusted to 24, 48 or 72 dSm-1. Salt tolerances of the grasses were assessed on the basis of their shoot and root growth, leaf firing and turf quality. Regression analysis indicated that Zoysiajaponica (Japanese lawn grass) (JG), Stenotaphrum secundatum (St. Augustine) (SA), Cynodon dactylon (satiri) (BS), Zoysia teneuifolia (Korean grass) (KG), Digitaria didactyla (Serangoon grass) (SG), Cynodon dactylon (Tifdwarf) (TD), Paspalum notatum (Bahia grass) (BG) and Axonopus compressus(Pearl blue) (PB) suffered a 50% shoot growth reduction at 36.0, 31.8, 30.9, 28.4, 26.4, 25.7, 20.0 and 18.6 dSm1 of salinity, respectively and a root growth reduction at44.9, 43.7, 33.4, 31.0, 29.5 27.5, 21.5 and 21.4 dSm- of salinity, respectively. Leaf firing and turf quality of the selected species, as a whole, were also found to be affected harmoniously with the change in root and shoot growth. On the basis of the experimental results the selected species were ranked for salinity tolerance as JG>SA>BS>KG>SG >TD>BG>PB.
    Matched MeSH terms: Plant Roots/growth & development
  9. Production of biomass and bioactive compounds from adventitious roots by optimization of culturing conditions of Eurycoma longifolia in balloon-type bubble bioreactor system
    Lulu T, Park SY, Ibrahim R, Paek KY
    J Biosci Bioeng, 2015 Jun;119(6):712-7.
    PMID: 25511788 DOI: 10.1016/j.jbiosc.2014.11.010
    The present study aimed to optimize the conditions for the production of adventitious roots from Eurycoma longifolia Jack, an important medicinal woody plant, in bioreactor culture. The effects of the type and concentration of auxin on root growth were studied, as well as the effects of the NH4(+):NO3(-) ratio on adventitious root growth and the production of phenolics and flavonoids. Approximately 5 g L(-1) fresh weight of adventitious roots was inoculated into a 3 L balloon-type bubble bioreactor, which contained 2 L 3/4 MS medium supplemented with 30 g L(-1) sucrose and cultures were maintained in the dark for 7 weeks at 24 ± 1°C. Higher concentrations of IBA (7.0 and 9.0 mg L(-1)) and NAA (5.0 mg L(-1)) enhanced the biomass and accumulation of total phenolics and flavonoids. The adventitious roots were thin, numerous, and elongated in 3/4 MS medium supplemented with 5.0 and 7.0 mg L(-1) IBA, whereas the lateral roots were shorter and thicker with 5.0 mg L(-1) NAA compared with IBA treatment. The optimum biomasses of 50.22 g L(-1) fresh weight and 4.60 g L(-1) dry weight were obtained with an NH4(+):NO3(-) ratio of 15:30. High phenolic and flavonoid productions (38.59 and 11.27 mg L(-1) medium, respectively) were also obtained with a ratio of 15:30. Analysis of the 2,2-diphenyl-1-picrylhydrazyl (DPPH)-scavenging activity indicated higher antioxidant activity with an NH4(+):NO3(-) ratio of 30:15. These results suggest that balloon-type bubble bioreactor cultures are suitable for the large-scale commercial production of E. longifolia adventitious roots which contain high yield of bioactive compounds.
    Matched MeSH terms: Plant Roots/growth & development*
  10. Fulltext Plant regeneration and cellular behaviour studies in Celosia cristata grown in vivo and in vitro
    Taha RM, Wafa SN
    ScientificWorldJournal, 2012;2012:359413.
    PMID: 22593677 DOI: 10.1100/2012/359413
    Tissue culture studies of Celosia cristata were established from various explants and the effects of various hormones on morphogenesis of this species were examined. It was found that complete plant regeneration occurred at highest percentage on MS medium supplemented with 2.0 mg/L NAA and 1.5 mg/L BAP, with the best response showed by shoot explants. In vitro flowering was observed on MS basal medium after six weeks. The occurrence of somaclonal variation and changes in cellular behavior from in vivo and in vitro grown plants were investigated through cytological studies and image analysis. It was observed that Mitotic Index (MI), mean chromosome numbers, and mean nuclear to cell area ratio of in vitro root meristem cells were slightly higher compared to in vivo values. However, in vitro plants produced lower mean cell areas but higher nuclear areas when compared to in vivo plants. Thus, no occurrence of somaclonal variation was detected, and this was supported by morphological features of the in vitro plants.
    Matched MeSH terms: Plant Roots/growth & development
  11. Plant growth-promoting bacteria as potential bio-inoculants and biocontrol agents to promote black pepper plant cultivation
    Lau ET, Tani A, Khew CY, Chua YQ, Hwang SS
    Microbiol Res, 2020 Nov;240:126549.
    PMID: 32688172 DOI: 10.1016/j.micres.2020.126549
    Black pepper production in Malaysia was restricted by various diseases. Hazardous chemical products appear to be the best solution to control diseases in black pepper cultivation. However, persistence of chemical residues in peppercorns could affect the quality of exports and consumptions. Application of fertilizers is crucial to sustain pepper growth and high yield. But, continuous use of chemical fertilizers could affect the soil ecosystem and eventually restrict nutrient uptake by pepper roots. Therefore, we propose biological approaches as an alternative solution instead of chemical products to sustain pepper cultivation in Malaysia. In this study, we have isolated a total of seven indigenous rhizobacteria antagonistic to soil-borne Fusarium solani, the causal fungus of slow decline, the most serious debilitating disease of black pepper in Malaysia. The isolated bacteria were identified as Bacillus subtilis, Bacillus siamensis, Brevibacillus gelatini, Pseudomonas geniculata, Pseudomonas beteli, Burkholderia ubonensis and Burkholderia territorii. These bacteria were effective in production of antifungal siderophore with the amount of 53.4 %-73.5 % per 0.5 mL of cell-free supernatants. The bacteria also produced appreciable amount of chitinase with chitinolytic index was ranged from 1.19 to 1.76. The bacteria have shown phosphate solubilizing index within 1.61 to 2.01. They were also efficient in ACC deaminase (0.52 mM-0.62 mM) and ammonia (60.3 mM-75.3 mM) production. The isolated antagonists were efficacious in stimulation of black pepper plant growth and root development through IAA (10.5 μg/mL-42.6 μg/mL) secretion. In conclusion, the isolated rhizobacteria are potent to be developed not only as biocontrol agents to minimize the utilization of hazardous chemicals in black pepper disease management, but also developed as bio-fertilizers to improve black pepper plant growth due to their capabilities in plant growth-promotion.
    Matched MeSH terms: Plant Roots/growth & development
  12. Phytoextraction of As and Fe using Hibiscus cannabinus L. from soil polluted with landfill leachate
    Meera M, Agamuthu P
    Int J Phytoremediation, 2012 Feb;14(2):186-99.
    PMID: 22567704
    Terrestrial plants as potential phytoremediators for remediation of surface soil contaminated with toxic metals have gained attention in clean-up technologies. The potential of kenaf (Hibiscus cannabinus L.) to offer a cost-effective mechanism to remediate Fe and As from landfill leachate-contaminated soil was investigated. Pot experiment employing soil polluted with treatments of Jeram landfill leachate was conducted for 120 days. Plants were harvested after 8th, 12th, and 16th weeks of growth. Accumulation of Fe and As was assessed based on Bioconcentration Factor and Translocation Factor. Results showed sequestration of 0.06-0.58 mg As and 66.82-461.71 mg Fe per g plant dry weight in kenaf root, which implies that kenaf root can be an bioavailable sink for toxic metals. Insignificant amount of Fe and As was observed in the aerial plant parts (< 12% of total bioavailable metals). The ability of kenaf to tolerate these metals and avoid phytotoxicity could be attributed to the stabilization of the metals in the roots and hence reduction of toxic metal mobility (TF < 1). With the application of leachate, kenaf was also found to have higher biomass and subsequently recorded 11% higher bioaccumulation capacity, indicating its suitability for phytoextraction of leachate contaminated sites.
    Matched MeSH terms: Plant Roots/growth & development
  13. Fulltext Phenazine from Pseudomonas aeruginosa UPMP3 induced the host resistance in oil palm (Elaeis guineensis Jacq.)-Ganoderma boninense pathosystem
    Parvin W, Govender N, Othman R, Jaafar H, Rahman M, Wong MY
    Sci Rep, 2020 Sep 24;10(1):15621.
    PMID: 32973199 DOI: 10.1038/s41598-020-72156-7
    Pseudomonas aeruginosa developed its biocontrol agent property through the production of antifungal derivatives, with the phenazine among them. In this study, the applications of crude phenazine synthesized by Pseudomonas aeruginosa UPMP3 and hexaconazole were comparatively evaluated for their effectiveness to suppress basal stem rot infection in artificially G. boninense-challenged oil palm seedlings. A glasshouse experiment under the randomized completely block design was set with the following treatments: non-inoculated seedlings, G. boninense inoculated seedlings, G. boninense inoculated seedlings with 1 mg/ml phenazine application, G. boninense inoculated seedlings with 2 mg/ml phenazine application and G. boninense inoculated seedlings with 0.048 mg/ml hexaconazole application. Seedlings were screened for disease parameters and plant vigour traits (plant height, plant fresh weight, root fresh, and dry weight, stem diameter, and total chlorophyll) at 1-to-4 month post-inoculation (mpi). The application of 2 mg/ml phenazine significantly reduced disease severity (DS) at 44% in comparison to fungicide application (DS = 67%). Plant vigour improved from 1 to 4 mpi and the rate of disease reduction in seedlings with phenazine application (2 mg/ml) was twofold greater than hexaconazole. At 4, 6 and 8 wpi, an up-regulation of chitinase and β-1,3 glucanase genes in seedlings treated with phenazine suggests the involvement of induced resistance in G. boninense-oil palm pathosystem.
    Matched MeSH terms: Plant Roots/growth & development*
  14. Optimization of an efficient semi-solid culture protocol for sterilization and plant regeneration of Centella asiatica (L.) as a medicinal herb
    Moghaddam SS, Jaafar HB, Aziz MA, Ibrahim R, Rahmat AB, Philip E
    Molecules, 2011;16(11):8981-91.
    PMID: 22439138
    The present study investigates the effects of different concentrations, as well as type of plant growth regulators (PGRs) and medium (MS, Duchefa) on the growth and development of Centella asiatica in semi-solid culture. In addition, a protocol for successful sterilization of C.asiatica explants prepared from field-grown plants highly exposed to fungal and bacterial contamination was determined. Results for sterilization treatments revealed that applying HgCl₂ and Plant Preservative Mixture (PPM) with cetrimide, bavistin and trimethoprim which were included after washing with tap water, followed by the addition of PPM in the medium, produced a very satisfactory result (clean culture 90 ± 1.33%) and TS5 (decon + cetrimide 1% + bavistin 150 mg/L + trimethoprim 50 mg/L + HgCl₂0.1% + PPM 2% soak and 2 mL/L in medium) was hence chosen as the best method of sterilization for C.asiatica. The synergistic combination of 6 benzylaminopurine (BAP) and 1-naphthaleneacetic acid (NAA) in concentrations of 2 mg/L and 0.1 mg/L, respectively, in Duchefa medium compared with MS induced the most optimal percentage of sprouted shoots (93 ± 0.667), number of shoots (5.2 ± 0.079) and nodes (4 ± 0.067) per explant, leaf per explant (14 ± 0.107) and shoot length (4.1 ± 0.67 cm). Furthermore, optimum rooting frequency (95.2 ± 0.81%), the number of roots/shoot (7.5 ± 0.107) and the mean root length (4.5 ± 0.133 cm) occurred for shoots that were cultured on full-strength MS medium containing 0.5 mg/L indole-3-butyric acid (IBA). In this study, the acclimatized plantlets were successfully established with almost 85% survival. The findings of this study have proven an efficient medium and PGR concentration for the mass propagation of C.asiatica. These findings would be useful in micropropagation and ex situ conservation of this plant.
    Matched MeSH terms: Plant Roots/growth & development
  15. Fulltext Microbial Contributions for Rice Production: From Conventional Crop Management to the Use of 'Omics' Technologies
    Doni F, Suhaimi NSM, Mispan MS, Fathurrahman F, Marzuki BM, Kusmoro J, et al.
    Int J Mol Sci, 2022 Jan 10;23(2).
    PMID: 35054923 DOI: 10.3390/ijms23020737
    Rice, the main staple food for about half of the world's population, has had the growth of its production stagnate in the last two decades. One of the ways to further improve rice production is to enhance the associations between rice plants and the microbiome that exists around, on, and inside the plant. This article reviews recent developments in understanding how microorganisms exert positive influences on plant growth, production, and health, focusing particularly on rice. A variety of microbial species and taxa reside in the rhizosphere and the phyllosphere of plants and also have multiple roles as symbiotic endophytes while living within plant tissues and even cells. They alter the morphology of host plants, enhance their growth, health, and yield, and reduce their vulnerability to biotic and abiotic stresses. The findings of both agronomic and molecular analysis show ways in which microorganisms regulate the growth, physiological traits, and molecular signaling within rice plants. However, many significant scientific questions remain to be resolved. Advancements in high-throughput multi-omics technologies can be used to elucidate mechanisms involved in microbial-rice plant associations. Prospectively, the use of microbial inoculants and associated approaches offers some new, cost-effective, and more eco-friendly practices for increasing rice production.
    Matched MeSH terms: Plant Roots/growth & development
  16. Fulltext Induction of hairy roots by various strains of Agrobacterium rhizogenes in different types of Capsicum species explants
    Md Setamam N, Jaafar Sidik N, Abdul Rahman Z, Che Mohd Zain CR
    BMC Res Notes, 2014 Jun 30;7:414.
    PMID: 24981787 DOI: 10.1186/1756-0500-7-414
    BACKGROUND: Capsicum annuum and Capsicum frutescens, also known as "chilies", belong to the Solanaceae family and have tremendous beneficial properties. The application of hairy root culture may become an alternative method for future development of these species by adding value, such as by increasing secondary metabolites and improving genetic and biochemical stability compared with normal Capsicum plants. Therefore, in this research, different types of explants of both species were infected with various Agrobacterium rhizogenes strains to provide more information about the morphology and induction efficiency of hairy roots. After 2 weeks of in vitro seed germination, young seedling explants were cut into three segments; the cotyledon, hypocotyl, and radical. Then, the explants were co-cultured with four isolated A. rhizogenes strains in Murashige & Skoog culture media (MS) containing decreasing carbenicillin disodium concentrations for one month.

    RESULTS: In this experiment, thick and short hairy roots were induced at all induction sites of C. annuum while thin, elongated hairy roots appeared mostly at wound sites of C. frutescens. Overall, the hairy root induction percentages of C. frutescens were higher compared with C. annuum. Hairy root initiation was observed earliest using radicles (1st week), followed by cotyledons (2nd week), and hypocotyls (3rd week). Cotyledon explants of both species had the highest induction frequency with all strains compared with the other explants types. Strains ATCC 13333 and ATCC 15834 were the most favourable for C. frutescens while ATCC 43056 and ATCC 43057 were the most favourable for C. annuum. The interactions between the different explants and strains showed significant differences with p-values < 0.0001 in both Capsicum species.

    CONCLUSIONS: Both Capsicum species were amenable to A. rhizogenes infection and hairy root induction is recommended for use as an alternative explants in future plant-based studies.

    Matched MeSH terms: Plant Roots/growth & development*
  17. Image analysis procedure for the optical scanning of fine-root dynamics: errors depending on the observer and root-viewing window size
    Kume T, Ohashi M, Makita N, Kho LK, Katayama A, Endo I, et al.
    Tree Physiol, 2018 12 01;38(12):1927-1938.
    PMID: 30452737 DOI: 10.1093/treephys/tpy124
    Clarifying the dynamics of fine roots is critical to understanding carbon and nutrient cycling in forest ecosystems. An optical scanner can potentially be used in studying fine-root dynamics in forest ecosystems. The present study examined image analysis procedures suitable for an optical scanner having a large (210 mm × 297 mm) root-viewing window. We proposed a protocol for analyzing whole soil images obtained by an optical scanner that cover depths of 0-210 mm. We tested our protocol using six observers with different experience in studying roots. The observers obtained data from the manual digitization of sequential soil images recorded for a Bornean tropical forest according to the protocol. Additionally, the study examined the potential tradeoff between the soil image size and accuracy of estimates of fine-root dynamics in a simple exercise. The six observers learned the protocol and obtained similar temporal patterns of fine-root growth and biomass with error of 10-20% regardless of their experience. However, there were large errors in decomposition owing to the low visibility of decomposed fine roots. The simple exercise revealed that a smaller root-viewing window (smaller than 60% of the original window) produces patterns of fine-root dynamics that are different from those for the original window size. The study showed the high applicability of our image analysis approach for whole soil images taken by optical scanners in estimating the fine-root dynamics of forest ecosystems.
    Matched MeSH terms: Plant Roots/growth & development*
  18. Fulltext Identification of functionally important microRNAs from rice inflorescence at heading stage of a qDTY4.1-QTL bearing Near Isogenic Line under drought conditions
    Cheah BH, Jadhao S, Vasudevan M, Wickneswari R, Nadarajah K
    PLoS One, 2017;12(10):e0186382.
    PMID: 29045473 DOI: 10.1371/journal.pone.0186382
    A cross between IR64 (high-yielding but drought-susceptible) and Aday Sel (drought-tolerant) rice cultivars yielded a stable line with enhanced grain yield under drought screening field trials at International Rice Research Institute. The major effect qDTY4.1 drought tolerance and yield QTL was detected in the IR77298-14-1-2-10 Backcrossed Inbred Line (BIL) and its IR87705-7-15-B Near Isogenic Line (NIL) with 93.9% genetic similarity to IR64. Although rice yield is extremely susceptible to water stress at reproductive stage, currently, there is only one report on the detection of drought-responsive microRNAs in inflorescence tissue of a Japonica rice line. In this study, more drought-responsive microRNAs were identified in the inflorescence tissues of IR64, IR77298-14-1-2-10 and IR87705-7-15-B via next-generation sequencing. Among the 32 families of inflorescence-specific non-conserved microRNAs that were identified, 22 families were up-regulated in IR87705-7-15-B. Overall 9 conserved and 34 non-conserved microRNA families were found as drought-responsive in rice inflorescence with 5 conserved and 30 non-conserved families induced in the IR87705-7-15-B. The observation of more drought-responsive non-conserved microRNAs may imply their prominence over conserved microRNAs in drought response mechanisms of rice inflorescence. Gene Ontology annotation analysis on the target genes of drought-responsive microRNAs identified in IR87705-7-15-B revealed over-representation of biological processes including development, signalling and response to stimulus. Particularly, four inflorescence-specific microRNAs viz. osa-miR5485, osa-miR5487, osa-miR5492 and osa-miR5517, and two non-inflorescence specific microRNAs viz. osa-miR169d and osa-miR169f.2 target genes that are involved in flower or embryonic development. Among them, osa-miR169d, osa-miR5492 and osa-miR5517 are related to flowering time control. It is also worth mentioning that osa-miR2118 and osa-miR2275, which are implicated in the biosynthesis of rice inflorescence-specific small interfering RNAs, were induced in IR87705-7-15-B but repressed in IR77298-14-1-2-10. Further, gene search within qDTY4.1 QTL region had identified multiple copies of NBS-LRR resistance genes (potential target of osa-miR2118), subtilisins and genes implicated in stomatal movement, ABA metabolism and cuticular wax biosynthesis.
    Matched MeSH terms: Plant Roots/growth & development
  19. Genotoxicity assessment of raw and treated water samples using Allium cepa assay: evidence from Perak River, Malaysia
    Malakahmad A, Manan TSBA, Sivapalan S, Khan T
    Environ Sci Pollut Res Int, 2018 Feb;25(6):5421-5436.
    PMID: 29209979 DOI: 10.1007/s11356-017-0721-8
    Allium cepa assay was carried out in this study to evaluate genotoxic effects of raw and treated water samples from Perak River in Perak state, Malaysia. Samples were collected from three surface water treatment plants along the river, namely WTPP, WTPS, and WTPK. Initially, triplicates of equal size Allium cepa (onions) bulbs, 25-30 mm in diameter and average weight of 20 g, were set up in distilled water for 24 h at 20 ± 2 °C and protected from direct sunlight, to let the roots to grow. After germination of roots (0.5-1.0 cm in length), bulbs were transferred to collected water samples each for a 96-h period of exposure. The root physical deformations were observed. Genotoxicity quantification was based on mitotic index and genotoxicity level. Statistical analysis using cross-correlation function for replicates from treated water showed that root length has inverse correlation with mitotic indices (r = - 0.969) and frequencies of cell aberrations (r = - 0.976) at lag 1. Mitotic indices and cell aberrations of replicates from raw water have shown positive correlation at lag 1 (r = 0.946). Genotoxicity levels obtained were 23.4 ± 1.98 (WTPP), 26.68 ± 0.34 (WTPS), and 30.4 ± 1.13 (WTPK) for treated water and 17.8 ± 0.18 (WTPP), 37.15 ± 0.17 (WTPS), and 47.2 ± 0.48 (WTPK) for raw water. The observed cell aberrations were adherence, chromosome delay, C-metaphase, chromosome loss, chromosome bridge, chromosome breaks, binucleated cell, mini cell, and lobulated nuclei. The morphogenetic deformations obtained were likely due to genotoxic substances presence in collected water samples. Thus, water treatment in Malaysia does not remove genotoxic compounds.
    Matched MeSH terms: Plant Roots/growth & development
  20. Fulltext Eliminating aluminum toxicity in an acid sulfate soil for rice cultivation using plant growth promoting bacteria
    Panhwar QA, Naher UA, Radziah O, Shamshuddin J, Razi IM
    Molecules, 2015 Feb 20;20(3):3628-46.
    PMID: 25710843 DOI: 10.3390/molecules20033628
    Aluminum toxicity is widely considered as the most important limiting factor for plants growing in acid sulfate soils. A study was conducted in laboratory and in field to ameliorate Al toxicity using plant growth promoting bacteria (PGPB), ground magnesium limestone (GML) and ground basalt. Five-day-old rice seedlings were inoculated by Bacillus sp., Stenotrophomonas maltophila, Burkholderia thailandensis and Burkholderia seminalis and grown for 21 days in Hoagland solution (pH 4.0) at various Al concentrations (0, 50 and 100 μM). Toxicity symptoms in root and leaf were studied using scanning electron microscope. In the field, biofertilizer (PGPB), GML and basalt were applied (4 t·ha-1 each). Results showed that Al severely affected the growth of rice. At high concentrations, the root surface was ruptured, leading to cell collapse; however, no damages were observed in the PGPB inoculated seedlings. After 21 days of inoculation, solution pH increased to >6.0, while the control treatment remained same. Field study showed that the highest rice growth and yield were obtained in the bio-fertilizer and GML treatments. This study showed that Al toxicity was reduced by PGPB via production of organic acids that were able to chelate the Al and the production of polysaccharides that increased solution pH. The release of phytohormones further enhanced rice growth that resulted in yield increase.
    Matched MeSH terms: Plant Roots/growth & development
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