Genetic Architecture of Spotted Stem Borer Resistance in Sorghum As Inferred From Qtl Mapping and Synteny with the Maize Genome uri icon

abstract

  • The present investigation was carried out to characterize the genetic architecture ofspotted stem borer resistance and related agronomic and morphological traits insorghum. The experimental material for this study consisted of 266 RILs derived froma cross between susceptible parent ICSV 745 and resistant parent PB 15520. TheseRILs were evaluated for phenotypic traits during the 2007 and 2008 rainy seasonsunder artificial infestation of stem borer, and were genotyped with 90 polymorphicSSR markers for linkage map construction and QTL analysis.The RILs exhibited wide variation for the observed traits across both of thescreening environments. The mean performance of RILs for most of the spotted stemborer resistance except stem tunneling, neared the mid-parental value. Among theobserved agronomic and morphological traits, except for testa (presence vs absence)and agronomic performance score, the means of RIL population were skewed towardsthat of one of the parents. High G×E interaction effects was observed in the RILpopulation progenies for all the resistance component, agronomic and morphologicaltraits except plant color score and seedling basal pigmentation score, which arelargely controlled by single major genes. Across-environment, heritability estimatesfor the resistance component traits were low to moderate, while for most of theagronomic and morphological traits they were high. From the frequency distributionspolygenic inheritance was inferred for most of the observed spotted stem borerresistance and agronomic traits. Presence of transgressive segregation for all theobserved resistance component traits except recovery resistance score and allobserved agronomic traits ? seedling vigor, plant height, time to 50% flowering andnumber of nodes suggesting that favorable and unfavorable alleles for these traits aredispersed between the two RIL parental lines. A significant and positive associationwas observed among all the observed resistance component traits, except stemtunneling. Significant association was also observed between various agronomic andmorphological traits with resistance component traits such as plant height with stemtunneling, deadheart incidence with time to 50% flowering, plant color with leafdamage score and overall resistance score and recovery resistance score with bothplant height and number of nodes

publication date

  • 2010