Genetic mapping and quantitative trait locus analysis of resistance to sterility mosaic disease in pigeonpea [Cajanus cajan (L.) Millsp.]

Abstract

a b s t r a c tSterility mosaic disease (SMD), considered as the "green plague of pigeonpea" and caused by pigeonpea sterility mosaic virus (PPSMV) is one of the major biotic factors, which leads to heavy yield losses and hence poses a big challenge for pigeonpea production in the Indian subcontinent. Variability in the sterility mosaic pathogen revealed the occurrence of five different isolates in India. Among them, three distinct SMD isolates have been characterized, viz., Patancheru, Bangalore and Coimbatore. Molecular tools offer a viable option to tackle these biotic stresses via identification of the genomic regions associated with the trait such as SMD resistance. With an aim of identifying the gene(s)/QTLs linked with SMD resistance, two F 2 populations, i.e. ICP 8863 × ICPL 20097 (segregating for Patancheru SMD isolate) and TTB 7 × ICP 7035 (segregating for both Patancheru and Bangalore SMD isolates) were developed and F 2:3 families were phenotyped for resistance to respective isolate(s) of SMD. After screening over 3000 SSR markers on parental genotypes of each mapping population, intra-specific genetic maps comprising of 11 linkage groups and 120 and 78 SSR loci were developed for ICP 8863 × ICPL 20097 and TTB 7 × ICP 7035 populations, respectively. Composite interval mapping (CIM) based QTL analysis by using genetic mapping and phenotyping data provided four QTLs for Patancheru SMD isolate and two QTLs for Bangalore SMD isolate. Identification of different QTLs for resistance to Patancheru and Bangalore SMD isolates is an indication of involvement of different genes conferring the resistance to these two SMD isolates. One QTL namely qSMD4 identified within an interval of 2.8 cM on LG 7 explaining 24.72% of phenotypic variance, once it is validated in other genetic background, seems to be a promising QTL for use in marker assisted selection. In summary, this is the first study on development of intra-specific genetic maps and identification of QTLs for SMD resistance in pigeonpea.

Molecular mapping and inheritance of restoration of fertility (Rf) in A4 hybrid system in pigeonpea (Cajanus cajan (L.) Millsp.)

“…Subsequently SSR marker-based genetic map was developed by Bohra et al (2011). Soon after this, intra-specific genetic maps were also generated using SSR markers with relatively very low marker density (Gnanesh et al 2011; Bohra et al 2012). SNP-based genotyping assays were also deployed for genetic map construction using inter-specific (Saxena et al 2012) and intra-specific mapping populations (Kumawat et al 2012).…”

Genotyping-by-sequencing of three mapping populations for identification of candidate genomic regions for resistance to sterility mosaic disease in pigeonpea

“…Therefore, limited numbers of markers were available for genetic mapping which in turn resulted in producing very low density genetic maps in cultivated pigeonpea 6, 9 . For instance, the number of SSR markers in individual component genetic maps ranged from 59 to 140 while the consensus map constructed using six component maps had only 339 markers 6 .…”

Study of Sterility Mosaic Disease Resistance on Immortal Population in Pigeonpea

“…Saxena (2008) proposed that, genetics of PSMD depend on the resistance source, PSMV isolates and scoring methods and hence the resistance to PSMD in pigeonpea appears to be complex. However, most of the studies have been reported as susceptibility is dominant and resistance to be under the control of recessive genes (Gnanesh et al, 2011 andGanapathy et al, 2012). These different inheritance patterns could be attributed to the difference in parents used for developing segregation population (Srinivas et al, 1997 andGanapathy et al, 2012) and different isolates used for screening (Srinivas et al, 1997).…”