MOLECULAR TAGGING OF YELLOW MOSAIC VIRUS (YMV) RESISTANCE IN MUNGBEAN [Vigna radiata (L.) Wilczek]
Loading...
Date
2019
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR
Abstract
The Yellow Mosaic Disease (YMD) in mungbean is reported to be the most devastating viral disease, caused by yellow mosaic virus (YMV) which is transmitted by whitefly (Bemisia tabaci). It causes considerable yield reduction even upto 85-100 %, depending on the stage of crop it affected. Development of resistant varieties is the most desired approach to alleviate the problem. However, the inheritance pattern of disease is not yet properly understood and also scope for the artificial screening of virus resistance is meager. Thus, posing the big challenge in selecting stabilized breeding line(s) or identification of resistance genotype(s). It is already proved that marker assisted selection can support the conventional approach with precision in every selection cycle. With this premise the present study was done to identify the molecular markers linked to YMV tolerance in mungbean employing bulk segregant analysis (BSA) and further validation of these markers through marker-trait co-segregation study.
The parental polymorphic survey between EC 396117 (YMV resistant parent) and TM 96-2 (YMV susceptible parent) was done with 81 SSR and ESTSSR markers. Of these, only 6 primers showed the polymorphic alleles with 7.4 % polymorphism between parents. Phenotyping of F2:3 population for YMV tolerance/susceptibility was done during the summer, 2018 and the contrasting progeny for the disease tolerance was identified. Ten resistant and ten susceptible F2 plants were selected for which the bulk segregant analysis (BSA) was performed with the polymorphic primers. Genotyping of bulks resulted in heterozygous allelic pattern for all the primers under study. This can be attributed to the occurrence of heterozygous nature of few selected F2 plants at these loci, the variable gene action (recessive/
xv
dominance) or might be due to the selection of disease escapes that constitute the resistant bulk, thus the possibility of occurrence of heterozygotes in the panel. Hence, further validation of these markers was done through marker-trait cosegregation study. A total of 135 F3 progenies were screened for YMV tolerance/ susceptibility during summer, 2019. Chi-square analysis of the disease score revealed 9 resistant :7 susceptible ratio, indicating complementary gene action. The polymorphic markers were validated in the F3 progenies that are derived from the respective F2 plants, involved in the BSA. From the marker-trait association study it is observed that, the primers CEDG 245 and CEDG305 have showed 70 % tolerant alleles in BYT. Nucleotide BLAST of the CEDG305 primer against sequence databases targeted a protein coding gene, LOC106765125 (Synaptotagmin-2-like) that has proved to be involved in cell to cell movement of diverse family of plant viruses including Begomoviruses. Hence, characterization of the identified gene through sequencing between the parents may further elucidate the responsible variations for YMV tolerance, possibly due to hindrance of cell to cell movement of YMV (Begomovirus) particles.
From the study, it can be suggested that the marker CEDG305 has the potential to use in identification of YMV resistant genotypes and the parent EC396117 can be successfully used in marker assisted breeding programmes as donor along with the identified marker source, to develop YMV tolerant varieties besides further confirmation of marker loci with the development of recombinant inbred lines/near isogenic lines. In conclusion, the bulk segregant analysis and there by the marker-trait validation study proved the possibility of identification of marker resource that linked with desirable trait at rapid rate by avoiding the expensive genotyping costs that associated with total population analysis, which usually followed in mapping approaches.
Description
D5868
Keywords
null