Displaying publications 1 - 20 of 88 in total

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  1. Ashkani S, Rafii MY, Rahim HA, Latif MA
    Mol. Biol. Rep., 2013 Mar;40(3):2503-15.
    PMID: 23203411 DOI: 10.1007/s11033-012-2331-3
    Rice blast is one of the major fungal diseases that badly reduce rice production in Asia including Malaysia. There is not much information on identification of QTLs as well as linked markers and their association with blast resistance within local rice cultivars. In order to understanding of the genetic control of blast in the F3 families from indica rice cross Pongsu seribu2/Mahsuri, an analysis of quantitative trait loci against one of the highly virulent Malaysian rice blast isolate Magnaporthe oryzae, P5.0 was carried out. Result indicated that partial resistance to this pathotype observed in the present study was controlled by multiple loci or different QTLs. In QTL analysis in F3 progeny fifteen QTLs on chromosomes 1, 2, 3, 5, 6, 11 and 12 for resistance to blast nursery tests was identified. Three of detected QTLs (qRBr-6.1, qRBr-11.4, and qRBr-12.1) had significant threshold (LOD >3) and approved by both IM and CIM methods. Twelve suggestive QTLs, qRBr-1.2, qRBr-2.1, qRBr-4.1, qRBr-5.1, qRBr-6.2, qRBr-6.3, qRBr-8.1, qRBr-10.1, qRBr-10.2, qRBr-11.1, qRBr-11.2 and qRBr-11.3) with Logarithmic of Odds (LOD) <3.0 or LRS <15) were distributed on chromosomes 1, 2, 4, 5, 6, 8, 10, and 11. Most of the QTLs detected using single isolate had the resistant alleles from Pongsu seribu 2 which involved in the resistance in the greenhouse. We found that QTLs detected for deferent traits for the using isolate were frequently located in similar genomic regions. Inheritance study showed among F3 lines resistance segregated in the expected ratio of 15: 1 for resistant to susceptible. The average score for blast resistance measured in the green house was 3.15, 1.98 and 29.95 % for three traits, BLD, BLT and % DLA, respectively.
  2. Ashkani S, Rafii MY, Rahim HA, Latif MA
    Biotechnol. Lett., 2013 May;35(5):799-810.
    PMID: 23315158 DOI: 10.1007/s10529-012-1130-1
    Malaysian rice, Pongsu Seribu 2, has wide-spectrum resistance against blast disease. Chromosomal locations conferring quantitative resistance were detected by linkage mapping with SSRs and quantitative trait locus (QTL) analysis. For the mapping population, 188 F3 families were derived from a cross between the susceptible cultivar, Mahsuri, and a resistant variety, Pongsu Seribu 2. Partial resistance to leaf blast in the mapping population was assessed. A linkage map covering ten chromosomes and consisting of 63 SSR markers was constructed. 13 QTLs, including 6 putative and 7 putative QTLs, were detected on chromosomes 1, 2, 3, 5, 6, 10, 11 and 12. The resulting phenotypic variation due to a single QTL ranged from 2 to 13 %. These QTLs accounted for approx. 80 % of the total phenotypic variation within the F3 population. Therefore, partial resistance to blast in Pongsu Seribu 2 is due to combined effects of multiple loci with major and minor effects.
  3. Rafii MY, Jalani BS, Rajanaidu N, Kushairi A, Puteh A, Latif MA
    Genet. Mol. Res., 2012;11(4):3629-41.
    PMID: 23096688 DOI: 10.4238/2012.October.4.10
    We evaluated 38 dura x pisifera (DP) oil palm progenies in four locations in Malaysia for genotype by environment interaction and genotypic stability studies. The DP progenies derived from crosses between pisifera palms of AVROS, Serdang S27B, Serdang 29/36, and Lever Cameroon were chosen to be the males' parent and Deli dura palms designated as females' parent. All the locations differed in terms of soil physical and chemical properties, and the soil types ranged from coastal clay to inland soils. The genotype by environment interaction and stability of the individual genotypes were analyzed for oil yield trait using several stability techniques. A genotype by environment interaction was detected for oil yield and it had a larger variance component than genotypic variance (σ(2)(gl)/σ(2)(g) = 139.7%). Genotype by environment interaction of oil yield was largely explained by a non-linear relationship between genotypic and environmental values. Overall assessment of individual genotypic stability showed that seven genotypes were highly stable and had consistent performance over the environments for the oil yield trait [total individual genotype stability scored more than 10 and mean oil yielded above the average of the environment (genotype means are more than 34.37 kg·palm(-1)·year(-1))]. These genotypes will be useful for oil palm breeding and tissue culture programs for developing high oil yielding planting materials with stable performance.
  4. Sohrabi M, Rafii MY, Hanafi MM, Siti Nor Akmar A, Latif MA
    ScientificWorldJournal, 2012;2012:416291.
    PMID: 22654604 DOI: 10.1100/2012/416291
    Genetic diversity is prerequisite for any crop improvement program as it helps in the development of superior recombinants. Fifty Malaysian upland rice accessions were evaluated for 12 growth traits, yield and yield components. All of the traits were significant and highly significant among the accessions. The higher magnitudes of genotypic and phenotypic coefficients of variation were recorded for flag leaf length-to-width ratio, spikelet fertility, and days to flowering. High heritability along with high genetic advance was registered for yield of plant, days to flowering, and flag leaf length-to-width ratio suggesting preponderance of additive gene action in the gene expression of these characters. Plant height showed highly significant positive correlation with most of the traits. According to UPGMA cluster analysis all accessions were clustered into six groups. Twelve morphological traits provided around 77% of total variation among the accessions.
  5. Bahari M, Rafii MY, Saleh GB, Latif MA
    ScientificWorldJournal, 2012;2012:543158.
    PMID: 22566772 DOI: 10.1100/2012/543158
    The experiments were carried out in two research stations (MARDI Bukit Tangga, Kedah, and MARDI Seberang Perai, Penang) in Malaysia. The crossings were performed using the four inbred lines in complete diallel cross including selfs and reciprocals. We evaluated the yield components and fruit characters such as fruit yield per plant, vine length, days to fruit maturity, fruit weight, total soluble solid content, and rind thickness over a period of two planting seasons. General combining ability and its interaction with locations were statistically significant for all characteristics except number of fruits per plant across the environments. Results indicated that the additive genetic effects were important to the inheritance of these traits and the expression of additive genes was influenced greatly by environments. In addition, specific combining ability effect was statistically evident for fruit yield per plant, vine length, days to first female flower, and fruit weight. Most of the characters are simultaneously controlled by additive and nonadditive gene effects. This study demonstrated that the highest potential and promising among the crosses was cross P2 (BL-14) × P3 (6372-4), which possessed prolific plants, with early maturity, medium fruit weight and high soluble solid contents. Therefore this hybrid might be utilized for developing high yielding watermelon cultivars and may be recommended for commercial cultivation.
  6. Noh A, Rafii MY, Saleh G, Kushairi A, Latif MA
    ScientificWorldJournal, 2012;2012:792601.
    PMID: 22701095 DOI: 10.1100/2012/792601
    The performance of 11 oil palm AVROS (Algemene Vereniging van Rubberplanters ter Oostkust van Sumatra) pisiferas was evaluated based on their 40 dura x pisifera (DxP) progenies tested on inland soils, predominantly of Serdang Series. Fresh fruit bunch (FFB) yield of each pisiferas ranged from 121.93 to 143.9 kg palm⁻¹ yr⁻¹ with trial mean of 131.62 kg palm⁻¹ yr⁻¹. Analysis of variance (ANOVA) showed low genetic variability among pisifera parents for most of the characters indicating uniformity of the pisifera population. This was anticipated as the AVROS pisiferas were derived from small population and were inbred materials. However, some of the pisiferas have shown good general combining ability (GCA) for certain important economic traits. Three pisiferas (P1 (0.174/247), P3 (0.174/498), P11 (0.182/308)) were identified of having good GCA for FFB yield while pisiferas P1 (0.174/247), P10 (0.182/348), and P11 (0.182/308) were good combiners for oil-to-bunch ratio (O/B). The narrow genetic base of these materials was the main obstacle in breeding and population improvement. However, efforts have been made to introgress this material with the vast oil palm germplasm collections of MPOB for rectifying the problem.
  7. Rafii MY, Shabanimofrad M, Puteri Edaroyati MW, Latif MA
    Mol. Biol. Rep., 2012 Jun;39(6):6505-11.
    PMID: 22307785 DOI: 10.1007/s11033-012-1478-2
    A sum of 48 accessions of physic nut, Jatropha curcas L. were analyzed to determine the genetic diversity and association between geographical origin using RAPD-PCR markers. Eight primers generated a total of 92 fragments with an average of 11.5 amplicons per primer. Polymorphism percentages of J. curcas accessions for Selangor, Kelantan, and Terengganu states were 80.4, 50.0, and 58.7%, respectively, with an average of 63.04%. Jaccard's genetic similarity co-efficient indicated the high level of genetic variation among the accessions which ranged between 0.06 and 0.81. According to UPGMA dendrogram, 48 J. curcas accessions were grouped into four major clusters at coefficient level 0.3 and accessions from same and near states or regions were found to be grouped together according to their geographical origin. Coefficient of genetic differentiation (G(st)) value of J. curcas revealed that it is an outcrossing species.
  8. 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'.
  9. Usman MG, Rafii MY, Martini MY, Oladosu Y, Kashiani P
    J. Sci. Food Agric., 2017 Mar;97(4):1164-1171.
    PMID: 27290898 DOI: 10.1002/jsfa.7843
    BACKGROUND: Studies on genotypic and phenotypic correlations among characters of crop plants are useful in planning, evaluating and setting selection criteria for the desired characters in a breeding program. The present study aimed to estimate the phenotypic correlation coefficients among yield and yield attributed characters and to work out the direct and indirect effects of yield-related characters on yield per plant using path coefficient analysis. Twenty-six genotypes of chili pepper were laid out in a randomized complete block design with three replications.

    RESULTS: Yield per plant showed positive and highly significant (P ≤ 0.01) correlations with most of the characters studied at both the phenotypic and genotypic levels. By contrast, disease incidence and days to flowering showed a significant negative association with yield. Fruit weight and number of fruits exerted positive direct effect on yield and also had a positive and significant (P ≤ 0.01) correlation with yield per plant. However, fruit length showed a low negative direct effect with a strong and positive indirect effect through fruit weight on yield and had a positive and significant association with yield.

    CONCLUSION: Longer fruits, heavy fruits and a high number of fruits are variables that are related to higher yields of chili pepper under tropical conditions and hence could be used as a reliable indicator in indirect selection for yield. © 2016 Society of Chemical Industry.

  10. Tajul Islam Chowdhury M, Salim Mian M, Taher Mia MA, Rafii MY, Latif MA
    Genet. Mol. Res., 2015 Dec 28;14(4):18140-52.
    PMID: 26782461 DOI: 10.4238/2015.December.23.1
    To examine the impact of regional and seasonal variations on the incidence and severity of sheath rot, a major seed-borne disease of rice caused by Sarocladium oryzae, data on incidence and severity were collected from 27 selected fields in the Gazipur, Rangpur, Bogra, Chittagong, Comilla, Gopalgonj, Jessore, Manikgonj, and Bhola districts of Bangladesh in rain-fed and irrigated conditions. Cultural variability of 29 pathogen isolates obtained from 8 different locations was studied on potato dextrose agar (PDA) and genetic variability was determined by DNA fingerprinting using variable number tandem repeat-polymerase chain reaction markers. Overall, disease incidence and severity were higher in irrigated rice. Disease incidence and severity were highest in the Bhola district in rain-fed rice and lowest in irrigated rice. Mycelial growth of 29 representative isolates was found to vary on PDA and the isolates were divided into 6 groups. The range of the overall size of conidia of the selected isolates was 2.40-7.20 x 1.20-2.40 μm. Analysis of the DNA fingerprint types of the 29 isolates of S. oryzae, obtained from the amplification reactions, revealed 10 fingerprinting types (FPTs) that were 80% similar. FPT-1 was the largest group and included 13 isolates (44.8%), while FPT-2 was the third largest group and included 3 isolates. Each of FPT-3, 4, 5, and 6 included only 1 isolate. We observed no relationship between cultural and genetic groupings.
  11. Talei D, Valdiani A, Rafii MY, Maziah M
    PLoS ONE, 2014;9(11):e112907.
    PMID: 25423252 DOI: 10.1371/journal.pone.0112907
    Separation of proteins based on the physicochemical properties with different molecular weight and isoelectric points would be more accurate. In the current research, the 45-day-old seedlings were treated with 0 (control) and 12 dS m(-1) of sodium chloride in the hydroponic system. After 15 days of salt exposure, the total protein of the fresh leaves and roots was extracted and analyzed using two-dimensional electrophoresis system (2-DE). The analysis led to the detection of 32 induced proteins (19 proteins in leaf and 13 proteins in the root) as well as 12 upregulated proteins (four proteins in leaf and eight proteins in the root) in the salt-treated plants. Of the 44 detected proteins, 12 were sequenced, and three of them matched with superoxide dismutase, ascorbate peroxidase and ribulose-1, 5-bisphosphate oxygenase whereas the rest remained unknown. The three known proteins associate with plants response to environmental stresses and could represent the general stress proteins in the present study too. In addition, the proteomic feedback of different accessions of A. paniculata to salt stress can potentially be used to breed salt-tolerant varieties of the herb.
  12. Ashkani S, Rafii MY, Shabanimofrad M, Ghasemzadeh A, Ravanfar SA, Latif MA
    Crit. Rev. Biotechnol., 2016;36(2):353-67.
    PMID: 25394538 DOI: 10.3109/07388551.2014.961403
    Rice blast disease, which is caused by the fungal pathogen Magnaporthe oryzae, is a recurring problem in all rice-growing regions of the world. The use of resistance (R) genes in rice improvement breeding programmes has been considered to be one of the best options for crop protection and blast management. Alternatively, quantitative resistance conferred by quantitative trait loci (QTLs) is also a valuable resource for the improvement of rice disease resistance. In the past, intensive efforts have been made to identify major R-genes as well as QTLs for blast disease using molecular techniques. A review of bibliographic references shows over 100 blast resistance genes and a larger number of QTLs (∼500) that were mapped to the rice genome. Of the blast resistance genes, identified in different genotypes of rice, ∼22 have been cloned and characterized at the molecular level. In this review, we have summarized the reported rice blast resistance genes and QTLs for utilization in future molecular breeding programmes to introgress high-degree resistance or to pyramid R-genes in commercial cultivars that are susceptible to M. oryzae. The goal of this review is to provide an overview of the significant studies in order to update our understanding of the molecular progress on rice and M. oryzae. This information will assist rice breeders to improve the resistance to rice blast using marker-assisted selection which continues to be a priority for rice-breeding programmes.
  13. Alam MA, Juraimi AS, Rafii MY, Abdul Hamid A
    Biomed Res Int, 2015;2015:105695.
    PMID: 25802833 DOI: 10.1155/2015/105695
    13 selected purslane accessions were subjected to five salinity levels 0, 8, 16, 24, and 32 dS m(-1). Salinity effect was evaluated on the basis of biomass yield reduction, physiological attributes, and stem-root anatomical changes. Aggravated salinity stress caused significant (P < 0.05) reduction in all measured parameters and the highest salinity showed more detrimental effect compared to control as well as lower salinity levels. The fresh and dry matter production was found to increase in Ac1, Ac9, and Ac13 from lower to higher salinity levels but others were badly affected. Considering salinity effect on purslane physiology, increase in chlorophyll content was seen in Ac2, Ac4, Ac6, and Ac8 at 16 dS m(-1) salinity, whereas Ac4, Ac9, and Ac12 showed increased photosynthesis at the same salinity levels compared to control. Anatomically, stem cortical tissues of Ac5, Ac9, and Ac12 were unaffected at control and 8 dS m(-1) salinity but root cortical tissues did not show any significant damage except a bit enlargement in Ac12 and Ac13. A dendrogram was constructed by UPGMA based on biomass yield and physiological traits where all 13 accessions were grouped into 5 clusters proving greater diversity among them. The 3-dimensional principal component analysis (PCA) has also confirmed the output of grouping from cluster analysis. Overall, salinity stressed among all 13 purslane accessions considering biomass production, physiological growth, and anatomical development Ac9 was the best salt-tolerant purslane accession and Ac13 was the most affected accession.
  14. Hasan N, Rafii MY, Abdul Rahim H, Nusaibah SA, Mazlan N, Abdullah S
    Genet. Mol. Res., 2017 Jan 23;16(1).
    PMID: 28128411 DOI: 10.4238/gmr16019280
    Rice (Oryza sativa L.) blast disease is one of the most destructive rice diseases in the world. The fungal pathogen, Magnaporthe oryzae, is the causal agent of rice blast disease. Development of resistant cultivars is the most preferred method to achieve sustainable rice production. However, the effectiveness of resistant cultivars is hindered by the genetic plasticity of the pathogen genome. Therefore, information on genetic resistance and virulence stability are vital to increase our understanding of the molecular basis of blast disease resistance. The present study set out to elucidate the resistance pattern and identify potential simple sequence repeat markers linked with rice blast disease. A backcross population (BC2F1), derived from crossing MR264 and Pongsu Seribu 2 (PS2), was developed using marker-assisted backcross breeding. Twelve microsatellite markers carrying the blast resistance gene clearly demonstrated a polymorphic pattern between both parental lines. Among these, two markers, RM206 and RM5961, located on chromosome 11 exhibited the expected 1:1 testcross ratio in the BC2F1 population. The 195 BC2F1 plants inoculated against M. oryzae pathotype P7.2 showed a significantly different distribution in the backcrossed generation and followed Mendelian segregation based on a single-gene model. This indicates that blast resistance in PS2 is governed by a single dominant gene, which is linked to RM206 and RM5961 on chromosome 11. The findings presented in this study could be useful for future blast resistance studies in rice breeding programs.
  15. Latif MA, Omar MY, Rafii MY, Malek MA, Tan SG
    C. R. Biol., 2013 Jul;336(7):354-63.
    PMID: 23932255 DOI: 10.1016/j.crvi.2013.06.006
    Morphological and host-plant relationship studies were conducted to differentiate two sympatric populations of brown planthopper (BPH), Nilaparvata lugens, one from rice (Oryza sativa) and the other from Leersia hexandra, a weed grass. In morphometric studies based on esterase activities, an UPGMA dendrogram using 17 quantitative morphological characters, including stridulatory organs (courtship signal-producing organs) between two sympatric populations of N. lugens, one from rice and the other from L. hexandra, a weed grass revealed that both populations were separated from each other. An out-group, N. bakeri, was found to be completely different from the two sympatric populations of N. lugens. Rice plants were best suited for the establishment of the rice-infesting population, and L. hexandra was a favourable host for the Leersia-infesting population. The individuals derived from one host did not thrive on the other host, as shown by a significant reduction in survival and nymphal development, ovipositional preferences, ovipositional response, and egg hatchability. Therefore, morphological and host-plant relationship studies indicate that rice-associated population with high esterase activities and L. heaxandra-associated population with low esterase activities are two closely related sibling species.
  16. Samedani B, Juraimi AS, Anwar MP, Rafii MY, Sheikh Awadz SH, Anuar AR
    ScientificWorldJournal, 2013;2013:308646.
    PMID: 24163618 DOI: 10.1155/2013/308646
    Axonopus compressus is one of the native soft grass species in oil palm in Malaysia which can be used as a cover crop. The competitive ability of A. compressus to overcome A. gangetica was studied using multiple-density, multiple-proportion replacements series under a glasshouse and full sunlight conditions in a poly bag for 10 weeks. A. compressus produced more dry weight and leaf area when competing against A. gangetica than in monoculture at both densities in the full sunlight and at high density in the shade. Moreover, the relative yield and relative crowding coefficients also indicated A. compressus is a stronger competitor than A. gangetica at both densities in the full sunlight and high density in the shade. It seemed that A. gangetica plants in the shade did not compete with each other and were more competitive against A. compressus as could influence A. compressus height in the shade. It is concluded that although suppression of A. gangetica by A. compressus occurred under full sunlight, irrespective of plant density, this ability reduced under shade as A. compressus density decreased. The result suggests that A. compressus in high density could be considered as a candidate for cover crops under oil palm canopy.
  17. Samedani B, Juraimi AS, Rafii MY, Anuar AR, Sheikh Awadz SA, Anwar MP
    ScientificWorldJournal, 2013;2013:695404.
    PMID: 24260020 DOI: 10.1155/2013/695404
    This study investigated the allelopathic effect of Axonopus compressus litter on Asystasia gangetica and Pennisetum polystachion. In experiment 1 the bioassays with 0, 10, 30, and 50 g L⁻¹ of aqueous A. compressus litter leachate were conducted. Experiment 2 was carried out by incorporating 0, 10, 20, 30, 40, and 50 g L⁻¹ of A. compressus litter leachate into soil. In experiment 3, the fate of A. compressus litter leachate phenolics in the soil was investigated. A. compressus leachates did not affect the germination percentage of A. gangetica and P. polystachion, but delayed germination of A. gangetica seeds and decreased seed germination time of P. polystachion. A. compressus litter leachates affected weeds hypocotyl length. Hypocotyl length reductions of 18 and 31% were observed at the highest concentration (50 g L⁻¹) compared to the control in A. gangetica and P. polystachion, respectively. When concentration of A. compressus litter leachate-amended soil increased A. gangetica and P. polystachion seedling shoot length, root length, seedling weight and chlorophyll concentration were not affected. The 5-week decomposition study of A. compressus showed that the phenolic compounds in A. compressus litter abruptly decreased about 52% after two weeks and remained steady until the end of the incubation.
  18. Sahebi M, Hanafi MM, Abdullah SN, Rafii MY, Azizi P, Nejat N, et al.
    Biomed Res Int, 2014;2014:971985.
    PMID: 24516858 DOI: 10.1155/2014/971985
    Silicon (Si) is the second most abundant element in soil after oxygen. It is not an essential element for plant growth and formation but plays an important role in increasing plant tolerance towards different kinds of abiotic and biotic stresses. The molecular mechanism of Si absorption and accumulation may differ between plants, such as monocotyledons and dicotyledons. Silicon absorption and accumulation in mangrove plants are affected indirectly by some proteins rich in serine and proline amino acids. The expression level of the genes responsible for Si absorption varies in different parts of plants. In this study, Si is mainly observed in the epidermal roots' cell walls of mangrove plants compared to other parts. The present work was carried out to discover further information on Si stress responsive genes in Rhizophora apiculata, using the suppression subtractive hybridization technique. To construct the cDNA library, two-month-old seedlings were exposed to 0.5, 1, and 1.5 mM SiO2 for 15 hrs and for 1 to 6 days resulting in a total of 360 high quality ESTs gained. Further examination by RT-PCR and real-time qRT-PCR showed the expression of a candidate gene of serine-rich protein.
  19. Miah G, Rafii MY, Ismail MR, Puteh AB, Rahim HA, Islam KhN, et al.
    Int J Mol Sci, 2013;14(11):22499-528.
    PMID: 24240810 DOI: 10.3390/ijms141122499
    Over the last few decades, the use of molecular markers has played an increasing role in rice breeding and genetics. Of the different types of molecular markers, microsatellites have been utilized most extensively, because they can be readily amplified by PCR and the large amount of allelic variation at each locus. Microsatellites are also known as simple sequence repeats (SSR), and they are typically composed of 1-6 nucleotide repeats. These markers are abundant, distributed throughout the genome and are highly polymorphic compared with other genetic markers, as well as being species-specific and co-dominant. For these reasons, they have become increasingly important genetic markers in rice breeding programs. The evolution of new biotypes of pests and diseases as well as the pressures of climate change pose serious challenges to rice breeders, who would like to increase rice production by introducing resistance to multiple biotic and abiotic stresses. Recent advances in rice genomics have now made it possible to identify and map a number of genes through linkage to existing DNA markers. Among the more noteworthy examples of genes that have been tightly linked to molecular markers in rice are those that confer resistance or tolerance to blast. Therefore, in combination with conventional breeding approaches, marker-assisted selection (MAS) can be used to monitor the presence or lack of these genes in breeding populations. For example, marker-assisted backcross breeding has been used to integrate important genes with significant biological effects into a number of commonly grown rice varieties. The use of cost-effective, finely mapped microsatellite markers and MAS strategies should provide opportunities for breeders to develop high-yield, blast resistance rice cultivars. The aim of this review is to summarize the current knowledge concerning the linkage of microsatellite markers to rice blast resistance genes, as well as to explore the use of MAS in rice breeding programs aimed at improving blast resistance in this species. We also discuss the various advantages, disadvantages and uses of microsatellite markers relative to other molecular marker types.
  20. Rufai S, Hanafi MM, Rafii MY, Ahmad S, Arolu IW, Ferdous J
    Biomed Res Int, 2013;2013:604598.
    PMID: 23862149 DOI: 10.1155/2013/604598
    The knowledge of genetic diversity of tree crop is very important for breeding and improvement program for the purpose of improving the yield and quality of its produce. Genetic diversity study and analysis of genetic relationship among 20 Moringa oleifera were carried out with the aid of twelve primers from, random amplified polymorphic DNA marker. The seeds of twenty M. oleifera genotypes from various origins were collected and germinated and raised in nursery before transplanting to the field at University Agricultural Park (TPU). Genetic diversity parameter, such as Shannon's information index and expected heterozygosity, revealed the presence of high genetic divergence with value of 1.80 and 0.13 for Malaysian population and 0.30 and 0.19 for the international population, respectively. Mean of Nei's gene diversity index for the two populations was estimated to be 0.20. In addition, a dendrogram constructed, using UPGMA cluster analysis based on Nei's genetic distance, grouped the twenty M. oleifera into five distinct clusters. The study revealed a great extent of variation which is essential for successful breeding and improvement program. From this study, M. oleifera genotypes of wide genetic origin, such as T-01, T-06, M-01, and M-02, are recommended to be used as parent in future breeding program.
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