Monday, November 13, 2006

Seed Yield and Insect Resistance of Near-Isogenic Soybean Lines with Introgressed Resistance QTL from PI 229358.

Caleb Warrington IV1, Shuquan Zhu1, John All1, Wayne Parrott2, and H. R. Boerma1. (1) Univ. of Georgia, 202 Ctr for Applied Genetic Tech., 111 Riverbend Rd, Athens, GA 30605, (2) Univ of Georgia, 101 Ctr for Applied Genetic Tech., Athens, GA 30605

The development of superior soybean cultivars [Glycine max (L.) Merr] exhibiting resistance to insects has been hindered due to linkage drag, a common phenomenon when introgressing alleles from exotic germplasm.  Simple-sequence repeat (SSR) markers were utilized previously to map soybean insect resistance (SIR) quantitative trait loci (QTL) in a ‘Cobb’ × PI 229358 population, and subsequently used to create near-isogenic lines (NILs) with SIR QTL in a ‘Benning’ genetic background.  SIR QTLs were mapped on linkage groups (LGs) M (SIRQTL-M), G (SIRQTL-G), H (SIRQTL-H), and D1b (SIRQTL-D1b).  The objectives of this study were to: (i) evaluate linkage drag for seed yield using Benning-derived NILs selected for SIRQTL-M, SIRQTL-H, and SIRQTL-G, (ii) assess the amount of PI 229358 genome surrounding the SIR QTL in each Benning NIL, (iii) evaluate the individual effects these three QTLs on antibiosis and antixenosis to corn earworm (CEW; Helicoverpa zea) and soybean looper (SBL; Pseudoplusia includens), and (iv) evaluate the effects of SIRQTL-M and the putative SIRQTL-D1b and their interactions in a Benning genetic background.  Yield data collected in five environments indicated that a significant (P=0.05) yield reduction of approximately 250 kg ha-1 is associated with SIRQTL-G compared to NILs without SIR QTL.  Overall there was no yield reduction associated with SIRQTL-M or SIRQTL-H.  A significant antixenosis and antibiosis effect was detected for SIRQTL-M in insect feeding assays, with no effect detected in antixenosis or antibiosis assays for SIRQTL-G or SIRQTL-H without the presence of PI 229358 alleles at SIRQTL-M.  These results support recent findings concerning these loci.  SIRQTL-D1b was found to not condition an appreciable level of antixenosis resistance to CEW.         


Handout (.pdf format, 143.0 kb)