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Aim: Alternaria blight caused by Alternaria lini is one of the major diseases of linseed which severely affects the yield and productivity. Here, we utilizes F2 mapping population derived from a resistant (JRF-4) and a susceptible (Chambal) genotypes of linseed and SSRs to identify the markers associated with Alternaria blight resistance using bulk segregant analysis approach. Methodology: A population consisting of 154 F2 individuals was developed from the cross between JRF-4 (resistant) and Chambal (susceptible). All 154 F2 individuals were screened with 100 polymorphic SSRs to identify extreme phenotype. Two bulk of extremes phenotypes (disease resistant and disease susceptible) from F2 mapping population were used for the bulked segregant analysis. The SSR primers that distinguished the parental lines were used to amplify the DNA from two bulks and banding pattern was observed to identify the SSRs that can differentiate the resistant and susceptible phenotypes bulk for Alternaria blight. Markers validation was carried out by amplifying DNA from individual plants of each bulk. Results: Out of 100, only 10 markers showed polymorphism among the bulks and of which only three markers viz., LUSc 898_3_12, Lu 2472 and Lu 3078 were able to differentiate the disease resistant and susceptible individuals from F2 population. Further, single marker linear regression approach was used to validate the association of selected polymorphic markers with the disease. The markers LUSc 898_3_12 and Lu 2472 showed significant regression which confirmed their linkage with Alternaria blight resistance. Interpretation: The two markers having significant regression can be used for diseases resistance breeding during marker assisted selection.
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ABSTRACT: In this study, we performed BSA to identify genetic markers linked to salt tolerance. We tested the genetic diversity among four bulked DNA samples of EMS induced mutant clones and one bulked DNA sample of non-mutated clone of Petunia for salt tolerance in in vitro callus cultures using RAPD and ISSR markers. Out of the 36 RAPD and 16 ISSR primers identified, 25 and 13 were effectively used to amplify genomic DNA of all the five bulked samples, respectively. In total, 114 RAPD amplifications products were obtained, of which 28% were polymorphic and 2% were genotype-specific bands. Out of the 64 ISSR amplification products obtained, 51% were polymorphic and 1% was genotype-specific bands. Results of this study indicated the existence of two patterns of distorted segregation among the studied markers. The first one indicates the differences between non-mutated clones of Petunia and its putative mutants. The second one was observed only between putative mutants and putative mutants tested for salt tolerance in in vitro culture. Both RAPD and ISSR analysis successfully detected the association with changes induced by chemical mutagenesis and salinity. Furthermore, our results indicate that BSA method can be useful in the rapid detection of molecular markers for further marker-assisted selection.
RESUMO: Neste estudo, realizamos BSA para identificar marcadores genéticos ligados à tolerância ao sal. Testamos a diversidade genética entre quatro amostras de DNA volumoso de clones mutantes induzidos por EMS, e uma amostra de DNA volumoso de clone não mutado de Petunia para tolerância a sal em culturas de calos in vitro usando marcadores RAPD e ISSR. Dos 36 primers RAPD e 16 ISSR identificados, 25 e 13 foram efetivamente usados para amplificar o DNA genômico de todas as cinco amostras, respectivamente. No total, foram obtidos 114 produtos de amplificação RAPD, dos quais 28% eram polimórficos e 2% eram bandas específicas de genótipos. Dos 64 produtos de amplificação ISSR obtidos, 51% eram polimórficos e 1% eram bandas específicas de genótipo. Os resultados deste estudo indicam a existência de dois padrões de segregação distorcida entre os marcadores estudados. O primeiro indica as diferenças entre os clones não mutantes de Petúnia e seus mutantes putativos. O segundo foi observado apenas entre mutantes putativos e mutantes putativos testados quanto à tolerância ao sal em cultura in vitro. Tanto a análise RAPD quanto a ISSR detectaram com sucesso a associação com alterações induzidas por mutagênese química e salinidade. Além disso, nossos resultados indicam que o método BSA pode ser útil na detecção rápida de marcadores moleculares para posterior seleção assistida por marcadores.
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Lentil, as an economical source of protein, minerals and vitamins, plays important role in nutritional security of the common man. Grown mainly in West Asia, North Africa (WANA) region and South Asia, it suffers from several biotic stresses such as wilt, rust, blight and broomrape. Lentil rust caused by autoecious fungus Uromyces viciae fabae (Pers.) Schroet is a serious lentil disease in Algeria, Bangladesh, Ethiopia, India, Italy, Morocco, Pakistan and Nepal. The disease symptoms are observed during flowering and early podding stages. Rust causes severe yield losses in lentil. It can only be effectively controlled by identifying the resistant source, understanding its inheritance and breeding for host resistance. The obligate parasitic nature of pathogen makes it difficult to maintain the pathogen in culture and to apply it to screen segregating progenies under controlled growth conditions. Hence, the use of molecular markers will compliment in identification of resistant types in different breeding programs. Here, we studied the inheritance of resistance to rust in lentil using F1, F2 and F2:3 from cross PL 8 (susceptible) x L 4149 (resistant) varieties. The phenotyping of lentil population was carried out at Sirmour, India. The result of genetic analysis revealed that a single dominant gene controls rust resistance in lentil genotype L 4149. The F2 population from this cross was used to tag and map the rust resistance gene using SSR and SRAP markers. Markers such as 270 SRAP and 162 SSR were studied for polymorphism and 101 SRAP and 33 SSRs were found to be polymorphic between the parents. Two SRAP and two SSR markers differentiated the resistant and susceptible bulks. SSR marker Gllc 527 was estimated to be linked to rust resistant locus at a distance of 5.9 cM. The Gllc 527 marker can be used for marker assisted selection for rust resistance; however, additional markers closer to rust resistant locus are required. The markers linked to the rust resistance gene can serve as starting points for map-based cloning of the rust resistance gene.
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We used 125 microsatellite markers to genotype the maize (Zea mays L.) near isogenic lines (NIL) L30HtPHtPRtRt and L30htphtpRtRt and the L40htphtprtrt line which contrast regarding the presence of the recently described dominant HtP and the recessive rt genes that confer resistance to Exserohilum turcicum. Five microsatellite markers revealed polymorphisms between the NIL and were considered candidate linked markers for the HtP resistance gene. Linkage was confirmed by bulked segregant sample (BSS) analysis of 32 susceptible and 34 resistant plants from a BC1F1 population derived from the cross (L30HtPHtPRtRt x L40htphtprtrt) x L40htphtprtrt. The bnlg198 and dupssr25 markers, both located on maize chromosome 2L (bin 2.08), were polymorphic between bulks. Linkage distances were estimated based on co-segregation data of the 32 susceptible plants and indicated distances of 28.7 centimorgans (cM) between HtP and bnlg198 and 23.5 cM between HtP and dupssr25. The same set of susceptible plants was also genotyped with markers polymorphic between L30HtPHtPRtRt and L40htphtprtrt in order to find markers linked to the rt gene. Marker bnlg197, from chromosome 3L (bin 3.06), was found linked to rt at a distance of 9.7 cM. This is the first report on the chromosomal locations of these newly described genes.
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Background: Duodenal ulcer (DU) is a multifactorial disorder with different etiological and pathogenetic mechanisms. Evidence for the role of genetic factors such as familial aggregation, twin studies, ABO blood groups, ABH nonsecretor status and hyperpepsinogenemia have been reported in DU. Genetic heterogeneity of cases with familial incidence will provide information regarding the association of qualitative and quantitative traits. Aim: Hence, the present study is envisaged at identifying the segregant and deviant groups based on parental phenotypes and their association with other quantitative markers. Materials AND Methods: 62 out of 462 endoscopically confirmed duodenal ulcer cases were considered for the analysis of genetic heterogeneity. This was resolved through the calculation of genetic risk estimates of sporadic cases in multiplex families based on different modes of inheritance and variation in associated genetic and biochemical markers. Results: Mean age at onset in simplex and multiplex cases was found to vary indicating the presence of genetic heterogeneity in the expression of the disease. Segregant and deviant groups were identified based on mortons probability risk estimates and examined for the possible association of qualitative and quantitative markers such as pepsinogen phenotype, serum and tissue pepsinogen levels, cathepsin E, malondialdehyde and ceruloplasmin levels. Conclusions: The study thus highlighted the presence of genetic heterogeneity in the expression of the disease. The risk factors associated with segregant type were normal serum and tissue pepsinogen levels increased malondialdehyde levels and association of AC phenotype while the deviant group was characterized by early age at onset with hyper pepsinogenemia and reduced cathepin E levels.
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White and brown strains of Flammulina velutipes were inter-crossed. All F1 showed light-brown fruitbody, suggesting that a gene for the brown fruitbody was incompletely dominant against the white one. And backcross experiment showed that more than two genes were involved in color determination. To isolate a molecular marker linked to fruitbody color, a set of primers was designed from a sequence of clones derived by a bulked segregant analysis. These markers showed a specific band which co-segregated with brown fruitbody forming strains.