Comparison of QTLs mapped in RILs and their test-cross progenies of tropical maize for insect resistance and agronomic traits uri icon

abstract

  • QuantItatIve traIt lOCI (QTL) affectlllg resIstance to south-western cornborer Dzatraea grandzosella (SWCB) and sugarcane borer Dzatraea saccharalzs(SCB) have been Identmed prevIOusly III F 23 lInes and recomblllantIllbred lInes (RILs) of tropIcal maJ.Ze uSlllg restnctlOn fragmentlength polymorphIsm (RFLP) analyses. Our 0 bJectlve was to detenrunewhether QTLs IdentIfied III these generatIOns are also expressed III testcrosses(TC) of RILs A population of 166 TC progemes was developedby crosslllg RILs from the cross CML131 (susceptIble) x CML67(resIstant) WIth the unrelated, susceptIble tester lIne CML216. ReSIstanceto first-generatIOn SWCB, measured as leaf-feedmg damage (LFD)under artIfiCIal mfestatlOn, and other agronomIc traIts were evaluatedm two envIronments for the TC progemes and three enVIronments for183 RILs The correlatIon between Ime per se and TC performance waslow for LFD and mtermeruate for most agronormc traIts EstImates ofthe genotYPIc vanance and hentabllItIes were smaller m the TC progemesthan m the RILs for all traIts QuantItatIve traIt lOCI were IdentIfiedusmg an RFLP Imkage map WIth 136 lOCI For LFD, four QTLswere detected m the TC progemes, of whIch two were m common WIthnme QTLs preVIously mapped m the RILs Few QTLs for agronolillctraits were common to the two types of progeny, because of the lowconsIstency of QTL pOSItIons for all traIts m RIL and TC progemes,the use of TC progemes should be conSIdered m QTL mappmg sturuesas the first step for marker-assIsted selectIOn m hybnd breedmg
  • Quantitative trait loci (QTL) affecting resistance to south-western corn borer Diatraea grandiosella (SWCB) and sugarcane borer Diatraea sac charalis (SCB) have been identified previously in F-2:3 lines and recombinant inbred lines (RILs) of tropical maize using restriction fragment length polymorphism (RFLP) analyses. Our objective was to determine whether QTLs identified in these generations are also expressed in test-crosses (TC) of RILs. A population of 166 TC progenies was developed by crossing RILs from the cross CML131 (susceptible) x CML67 (resistant) with the unrelated, susceptible tester line CML216. Resistance to first-generation SWCB, measured as leaf-feeding damage (LFD) under artificial infestation, and other agronomic traits were evaluated in two environments for the TC progenies and three environments for 183 RILs. The correlation between line per se and TC performance was low for LFD and intermediate for most agronomic traits. Estimates of the genotypic variance and heritabilities were smaller in the TC progenies than in the RILs for all traits. Quantitative trait loci were identified using an RFLP linkage map with 136 loci. For LFD, four QTLs were detected in the TC progenies, of which two were in common with nine QTLs previously mapped in the RILs. Few QTLs for agronomic traits were common to the two types of progeny, because of the low consistency of QTL positions for all traits in RIL and TC progenies, the use of TC progenies should be considered in QTL mapping studies as the first step for marker-assisted selection in hybrid breeding.

publication date

  • 1998
  • 1998
  • 1998