Displaying publications 61 - 74 of 74 in total

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  1. Fulltext Development of an Indirect ELISA and Dot-Blot Assay for Serological Detection of Rice Tungro Disease
    Henry Sum MS, Yee SF, Eng L, Poili E, Lamdin J
    Biomed Res Int, 2017;2017:3608042.
    PMID: 29201901 DOI: 10.1155/2017/3608042
    Rice tungro disease (RTD) is one of the most destructive diseases of rice in South and Southeast Asia. RTD is routinely detected based on visual observation of the plant. However, it is not always easy to identify the disease in the field as it is often confused with other diseases or physiological disorders. Here we report the development of two serological based assays for ease of detection of RTD. In this study we had developed and optimized an indirect ELISA and dot-blot assay for detection of RTD. The efficiency of both assays was evaluated by comparing the specificity and sensitivity of the assays to PCR assay using established primer sets. The indirect ELISA showed 97.5% and 96.6%, while the dot-blot assay showed 97.5% and 86.4% sensitivity and specificity, respectively, when compared to established PCR method. The high sensitivity and specificity of the two assays merit the use of both assays as alternative methods to diagnose RTD. Furthermore, the dot-blot assay is a simple, robust, and rapid diagnostic assay that is suitable for field test for it does not require any specialized equipment. This is a great advantage for diagnosing RTD in paddy fields, especially in the rural areas.
    Matched MeSH terms: Oryza/genetics
  2. Fulltext Susceptibility and tolerance of rice crop to salt threat: Physiological and metabolic inspections
    Ma NL, Che Lah WA, Abd Kadir N, Mustaqim M, Rahmat Z, Ahmad A, et al.
    PLoS One, 2018;13(2):e0192732.
    PMID: 29489838 DOI: 10.1371/journal.pone.0192732
    Salinity threat is estimated to reduce global rice production by 50%. Comprehensive analysis of the physiological and metabolite changes in rice plants from salinity stress (i.e. tolerant versus susceptible plants) is important to combat higher salinity conditions. In this study, we screened a total of 92 genotypes and selected the most salinity tolerant line (SS1-14) and most susceptible line (SS2-18) to conduct comparative physiological and metabolome inspections. We demonstrated that the tolerant line managed to maintain their water and chlorophyll content with lower incidence of sodium ion accumulation. We also examined the antioxidant activities of these lines: production of ascorbate peroxidase (APX) and catalase (CAT) were significantly higher in the sensitive line while superoxide dismutase (SOD) was higher in the tolerant line. Partial least squares discriminant analysis (PLS-DA) score plots show significantly different response for both lines after the exposure to salinity stress. In the tolerant line, there was an upregulation of non-polar metabolites and production of sucrose, GABA and acetic acid, suggesting an important role in salinity adaptation. In contrast, glutamine and putrescine were noticeably high in the susceptible rice. Coordination of different strategies in tolerant and susceptible lines show that they responded differently after exposure to salt stress. These findings can assist crop development in terms of developing tolerance mechanisms for rice crops.
    Matched MeSH terms: Oryza/genetics
  3. The 172-kb genomic DNA region of the O. rufipogon yld1.1 locus: comparative sequence analysis with O. sativa ssp. japonica and O. sativa ssp. indica
    Song BK, Hein I, Druka A, Waugh R, Marshall D, Nadarajah K, et al.
    Funct Integr Genomics, 2009 Feb;9(1):97-108.
    PMID: 18633654 DOI: 10.1007/s10142-008-0091-x
    Common wild rice (Oryza rufipogon) plays an important role by contributing to modern rice breeding. In this paper, we report the sequence and analysis of a 172-kb genomic DNA region of wild rice around the RM5 locus, which is associated with the yield QTL yld1.1. Comparative sequence analysis between orthologous RM5 regions from Oryza sativa ssp. japonica, O. sativa ssp. indica and O. rufipogon revealed a high level of conserved synteny in the content, homology, structure, orientation, and physical distance of all 14 predicted genes. Twelve of the putative genes were supported by matches to proteins with known function, whereas two were predicted by homology to rice and other plant expressed sequence tags or complementary DNAs. The remarkably high level of conservation found in coding, intronic and intergenic regions may indicate high evolutionary selection on the RM5 region. Although our analysis has not defined which gene(s) determine the yld1.1 phenotype, allelic variation and the insertion of transposable elements, among other nucleotide changes, represent potential variation responsible for the yield QTL. However, as suggested previously, two putative receptor-like protein kinase genes remain the key suspects for yld1.1.
    Matched MeSH terms: Oryza/genetics*
  4. 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: Oryza/genetics
  5. Fulltext FAR1 and FAR2 regulate the expression of genes associated with lipid metabolism in the rice blast fungus Magnaporthe oryzae
    bin Yusof MT, Kershaw MJ, Soanes DM, Talbot NJ
    PLoS One, 2014;9(6):e99760.
    PMID: 24949933 DOI: 10.1371/journal.pone.0099760
    The rice blast fungus Magnaporthe oryzae causes plant disease via specialised infection structures called appressoria. These dome-shaped cells are able to generate enormous internal pressure, which enables penetration of rice tissue by invasive hyphae. Previous studies have shown that mobilisation of lipid bodies and subsequent lipid metabolism are essential pre-requisites for successful appressorium-mediated plant infection, which requires autophagic recycling of the contents of germinated spores and germ tubes to the developing appressorium. Here, we set out to identify putative regulators of lipid metabolism in the rice blast fungus. We report the identification of FAR1 and FAR2, which encode highly conserved members of the Zn2-Cys6 family of transcriptional regulators. We generated Δfar1, Δfar2 and Δfar1Δfar2 double mutants in M. oryzae and show that these deletion mutants are deficient in growth on long chain fatty acids. In addition, Δfar2 mutants are also unable to grow on acetate and short chain fatty acids. FAR1 and FAR2 are necessary for differential expression of genes involved in fatty acid β-oxidation, acetyl-CoA translocation, peroxisomal biogenesis, and the glyoxylate cycle in response to the presence of lipids. Furthermore, FAR2 is necessary for expression of genes associated with acetyl-CoA synthesis. Interestingly, Δfar1, Δfar2 and Δfar1Δfar2 mutants show no observable delay or reduction in lipid body mobilisation during plant infection, suggesting that these transcriptional regulators control lipid substrate utilization by the fungus but not the mobilisation of intracellular lipid reserves during infection-related morphogenesis.
    Matched MeSH terms: Oryza/genetics
  6. Fulltext Molecular identification of Fusarium species in Gibberella fujikuroi species complex from rice, sugarcane and maize from Peninsular Malaysia
    Hsuan HM, Salleh B, Zakaria L
    Int J Mol Sci, 2011;12(10):6722-32.
    PMID: 22072914 DOI: 10.3390/ijms12106722
    The objective of this study was to identify Fusarium species in the Gibberella fujikuroi species complex from rice, sugarcane and maize as most of the Fusarium species in the species complex are found on the three crops. Isolates used were collected from the field and obtained from culture collection. The Fusarium isolates were initially sorted based on morphology and identifications confirmed based on the DNA sequence of the translation elongation factor 1-α (TEF-1α) gene. Based on the closest match of BLAST analysis, five species were recovered, namely, F. sacchari, F. fujikuroi, F. proliferatum, F. andiyazi and F. verticillioides. This is the first report regarding F. andiyazi from rice in Malaysia and Southeast Asia. The phylogenetic tree generated by using the neighbor joining method showed that isolates from the same species were grouped in the same clade. The present study indicated that Fusarium species in the G. fujikuroi species complex are widespread in rice, sugarcane and maize in Peninsular Malaysia. The findings also suggest that the use of morphological characters for identification of Fusarium species in the G. fujikuroi species complex from the three crops will lead to incorrect species designation.
    Matched MeSH terms: Oryza/genetics
  7. Fulltext RNAi-mediated down-regulation of the expression of OsFAD2-1: effect on lipid accumulation and expression of lipid biosynthetic genes in the rice grain
    Tiwari GJ, Liu Q, Shreshtha P, Li Z, Rahman S
    BMC Plant Biol, 2016 08 31;16(1):189.
    PMID: 27581494 DOI: 10.1186/s12870-016-0881-6
    BACKGROUND: The bran from polished rice grains can be used to produce rice bran oil (RBO). High oleic (HO) RBO has been generated previously through RNAi down-regulation of OsFAD2-1. HO-RBO has higher oxidative stability and could be directly used in the food industry without hydrogenation, and is hence free of trans fatty acids. However, relative to a classic oilseed, lipid metabolism in the rice grain is poorly studied and the genetic alteration in the novel HO genotype remains unexplored.

    RESULTS: Here, we have undertaken further analysis of role of OsFAD2-1 in the developing rice grain. The use of Illumina-based NGS transcriptomics analysis of developing rice grain reveals that knockdown of Os-FAD2-1 gene expression was accompanied by the down regulation of the expression of a number of key genes in the lipid biosynthesis pathway in the HO rice line. A slightly higher level of oil accumulation was also observed in the HO-RBO.

    CONCLUSION: Prominent among the down regulated genes were those that coded for FatA, LACS, SAD2, SAD5, caleosin and steroleosin. It may be possible to further increase the oleic acid content in rice oil by altering the expression of the lipid biosynthetic genes that are affected in the HO line.

    Matched MeSH terms: Oryza/genetics*
  8. A transgressive brown rice mediates favourable glycaemic and insulin responses
    Karupaiah T, Aik CK, Heen TC, Subramaniam S, Bhuiyan AR, Fasahat P, et al.
    J Sci Food Agric, 2011 Aug 30;91(11):1951-6.
    PMID: 21480266 DOI: 10.1002/jsfa.4395
    BACKGROUND: We evaluated glycaemic response of a brown rice variant (BR) developed by cross-breeding. Subjects (n = 9) consumed 50 g carbohydrate equivalents of BR, white rice (WR) and the polished brown rice (PR) in comparison to 50 g glucose reference (GLU) in a cross-over design. Plasma glucose and insulin at 0, 15, 45, 60, 90, 120 and 180 min were measured and incremental area under the curve (IAUC) and indices for glucose (GI) and insulin (II) calculated.
    RESULTS: BR compared to PR or WR produced the lowest postprandial glycaemia (GI: 51 vs 79 vs 86) and insulinaemia (II: 39 vs 63 vs 68) irrespective of amylose content (19 vs 23 vs 26.5%). Only BR was significantly different from GLU for both plasma glucose (P = 0.012) and insulin (P = 0.013) as well as IAUC(glu) (P = 0.045) and IAUC(ins) (P = 0.031). Glycaemic and insulinaemic responses correlated positively (r = 0.550, P < 0.001). Linear trends for IAUC(glu) and IAUC(ins) indicated a greater secretion of insulin tied in with a greater glycaemic response for WR (r(2) = 0.848), moderate for PR (r(2) = 0.302) and weakest for BR (r(2) = 0.122).
    CONCLUSION: The brown rice variant had the lowest GI and II values but these advantages were lost with polishing.
    Matched MeSH terms: Oryza/genetics*
  9. Fulltext Evaluating Crossbred Red Rice Variants for Postprandial Glucometabolic Responses: A Comparison with Commercial Varieties
    Se CH, Chuah KA, Mishra A, Wickneswari R, Karupaiah T
    Nutrients, 2016 May 20;8(5).
    PMID: 27213446 DOI: 10.3390/nu8050308
    Consumption of white rice predisposes some Asian populations to increased risk of type 2 diabetes. We compared the postprandial glucometabolic responses to three newly-developed crossbred red rice variants (UKMRC9, UKMRC10, UKMRC11) against three selected commercial rice types (Thai red, Basmati white, Jasmine white) using 50-g carbohydrate equivalents provided to 12 normoglycaemic adults in a crossover design. Venous blood was drawn fasted and postprandially for three hours. Glycaemic (GI) and insulin (II) indices, incremental areas-under-the-curves for glucose and insulin (IAUCins), indices of insulin sensitivity and secretion, lactate and peptide hormones (motilin, neuropeptide-Y, orexin-A) were analyzed. The lowest to highest trends for GI and II were similar i.e., UKMRC9 < Basmati < Thai red < UKMRC10 < UKMRC11 < Jasmine. Postprandial insulinaemia and IAUCins of only UKMRC9 were significantly the lowest compared to Jasmine. Crude protein and fiber content correlated negatively with the GI values of the test rice. Although peptide hormones were not associated with GI and II characteristics of test rice, early and late phases of prandial neuropeptide-Y changes were negatively correlated with postprandial insulinaemia. This study indicated that only UKMRC9 among the new rice crossbreeds could serve as an alternative cereal option to improve diet quality of Asians with its lowest glycaemic and insulinaemic burden.
    Matched MeSH terms: Oryza/genetics*
  10. Fulltext Screening and Expression of a Silicon Transporter Gene (Lsi1) in Wild-Type Indica Rice Cultivars
    Sahebi M, Hanafi MM, Rafii MY, Azizi P, Abiri R, Kalhori N, et al.
    Biomed Res Int, 2017;2017:9064129.
    PMID: 28191468 DOI: 10.1155/2017/9064129
    Silicon (Si) is one of the most prevalent elements in the soil. It is beneficial for plant growth and development, and it contributes to plant defense against different stresses. The Lsi1 gene encodes a Si transporter that was identified in a mutant Japonica rice variety. This gene was not identified in fourteen Malaysian rice varieties during screening. Then, a mutant version of Lsi1 was substituted for the native version in the three most common Malaysian rice varieties, MR219, MR220, and MR276, to evaluate the function of the transgene. Real-time PCR was used to explore the differential expression of Lsi1 in the three transgenic rice varieties. Silicon concentrations in the roots and leaves of transgenic plants were significantly higher than in wild-type plants. Transgenic varieties showed significant increases in the activities of the enzymes SOD, POD, APX, and CAT; photosynthesis; and chlorophyll content; however, the highest chlorophyll A and B levels were observed in transgenic MR276. Transgenic varieties have shown a stronger root and leaf structure, as well as hairier roots, compared to the wild-type plants. This suggests that Lsi1 plays a key role in rice, increasing the absorption and accumulation of Si, then alters antioxidant activities, and improves morphological properties.
    Matched MeSH terms: Oryza/genetics*
  11. Overexpression of monodehydroascorbate reductase from a mangrove plant (AeMDHAR) confers salt tolerance on rice
    Sultana S, Khew CY, Morshed MM, Namasivayam P, Napis S, Ho CL
    J Plant Physiol, 2012 Feb 15;169(3):311-8.
    PMID: 22024734 DOI: 10.1016/j.jplph.2011.09.004
    Monodehydroascorbate reductase (MDHAR), an important enzyme of the ascorbate-glutathione cycle, is involved in salt tolerance of plants through scavenging of reactive oxygen species (ROS). In this study, a cDNA encoding MDHAR from the mangrove plant Acanthus ebracteatus was introduced into rice to examine its role in salt tolerance. Three stable transgenic lines (MT22, MT24 and MT25) overexpressing AeMDHAR were selected in vitro using hygromycin and confirmed by PCR, quantitative reverse-transcription (qRT) PCR and enzyme assay. The transgenic line MT24 was predicted to possess a single copy of the transgene while the other two transgenic lines were predicted to have multiple transgene integrations. The AeMDHAR transcripts were detected only in transgenic rice lines but not in untransformed rice. The abundance of AeMDHAR transcripts in transgenic lines MT22 and MT25 was approximately 2.75 times the amount found in MT24. The transgenic rice lines overexpressing AeMDHAR showed a significant increase in MDHAR enzyme activity compared to untransformed plants under both NaCl and control conditions. All transgenic lines showed better yield attributes such as a higher tiller number and increased 1000-grain weight compared to non-transgenics. They also showed tolerance to salt at germination and seedling stages. The transgenic line MT24, which harbors a single copy of AeMDHAR, displayed a lower rate of sterility, a higher number of tillers and longer panicle compared to untransformed plants when subjected to salt stress.
    Matched MeSH terms: Oryza/genetics
  12. Brassinosteroid insensitive 1-associated kinase 1 (OsI-BAK1) is associated with grain filling and leaf development in rice
    Khew CY, Teo CJ, Chan WS, Wong HL, Namasivayam P, Ho CL
    J Plant Physiol, 2015 Jun 15;182:23-32.
    PMID: 26037695 DOI: 10.1016/j.jplph.2015.05.003
    Brassinosteroid Insensitive 1 (BRI1)-Associated Kinase I (BAK1) has been reported to interact with BRI1 for brassinosteroid (BR) perception and signal transduction that regulate plant growth and development. The aim of this study is to investigate the functions of a rice OsBAK1 homologue, designated as OsI-BAK1, which is highly expressed after heading. Silencing of OsI-BAK1 in rice plants produced a high number of undeveloped green and unfilled grains compared to the untransformed plants. Histological analyses demonstrated that embryos were either absent or retarded in their development in these unfilled rice grains of OsI-BAK1 RNAi plants. Down regulation of OsI-BAK1 caused a reduction in cell number and enlargement in leaf bulliform cells. Furthermore, transgenic rice plants overexpressing OsI-BAK1 were demonstrated to have corrugated and twisted leaves probably due to increased cell number that caused abnormal bulliform cell structure which were enlarged and plugged deep into leaf epidermis. The current findings suggest that OsI-BAK1 may play an important role in the developmental processes of rice grain filling and leaf cell including the bulliform cells.
    Matched MeSH terms: Oryza/genetics
  13. Fulltext Ser-653-Asn substitution in the acetohydroxyacid synthase gene confers resistance in weedy rice to imidazolinone herbicides in Malaysia
    Ruzmi R, Ahmad-Hamdani MS, Mazlan N
    PLoS One, 2020;15(9):e0227397.
    PMID: 32925921 DOI: 10.1371/journal.pone.0227397
    The continuous and sole dependence on imidazolinone (IMI) herbicides for weedy rice control has led to the evolution of herbicide resistance in weedy rice populations across various countries growing IMI herbicide-resistant rice (IMI-rice), including Malaysia. A comprehensive study was conducted to elucidate occurrence, level, and mechanisms endowing resistance to IMI herbicides in putative resistant (R) weedy rice populations collected from three local Malaysian IMI-rice fields. Seed bioassay and whole-plant dose-response experiments were conducted using commercial IMI herbicides. Based on the resistance index (RI) quantification in both experiments, the cross-resistance pattern of R and susceptible (S) weedy rice populations and control rice varieties (IMI-rice variety MR220CL2 and non-IMI-rice variety MR219) to imazapic and imazapyr was determined. A molecular investigation was carried out by comparing the acetohydroxyacid synthase (AHAS) gene sequences of the R and S populations and the MR220CL2 and MR219 varieties. The AHAS gene sequences of R weedy rice were identical to those of MR220CL2, exhibiting a Ser-653-Asn substitution, which was absent in MR219 and S plants. In vitro assays were conducted using analytical grade IMI herbicides of imazapic (99.3%) and imazapyr (99.6%) at seven different concentrations. The results demonstrated that the AHAS enzyme extracted from the R populations and MR220CL2 was less sensitive to IMI herbicides than that from S and MR219, further supporting that IMI herbicide resistance was conferred by target-site mutation. In conclusion, IMI resistance in the selected populations of Malaysian weedy rice could be attributed to a Ser-653-Asn mutation that reduced the sensitivity of the target site to IMI herbicides. To our knowledge, this study is the first to show the resistance mechanism in weedy rice from Malaysian rice fields.
    Matched MeSH terms: Oryza/genetics
  14. Plant genetic transformation efficiency of selected Malaysian rice based on selectable marker gene (hptII)
    Htwe NN, Ling HC, Zaman FQ, Maziah M
    Pak J Biol Sci, 2014 Apr;17(4):472-81.
    PMID: 25911833
    Rice is one of the most important cereal crops with great potential for biotechnology progress. In transformation method, antibiotic resistance genes are routinely used as powerful markers for selecting transformed cells from surrounding non-transformed cells. In this study, the toxicity level of hygromycin was optimized for two selected mutant rice lines, MR219 line 4 and line 9. The mature embryos were isolated and cultured on an MS medium with different hygromycin concentrations (0, 20, 40, 60, 80 and 100 mg L(-1)). Evidently, above 60 mg L(-1) was effective for callus formation and observed completely dead. Further there were tested for specific concentration (0-60). Although, 21.28% calli survived on the medium containing 45 mg L(-1) hygromycin, it seemed suitable for the identification of putative transformants. These findings indicated that a system for rice transformation in a relatively high frequency and the transgenes are stably expressed in the transgenic plants. Green shoots were regenerated from the explant under hygromycin stress. RT-PCR using hptII and gus sequence specific primer and Southern blot analysis were used to confirm the presence of the transgene and to determine the transformation efficiency for their stable integration in regenerated plants. This study demonstrated that the hygromycin resistance can be used as an effective marker for rice transformation.
    Matched MeSH terms: Oryza/genetics*
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