Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2012
Publication Date: N/A
Citation: N/A Interpretive Summary: Soybean yield is severely impacted by flooding stress and Phytophthora root rot when soils become saturated. DNA regions and markers associated with these traits were identified in the soybean mapping population PI 408105A x SS99 2281. The results indicated that while there was some overlapping, these two traits are independently inherited and that PI408105A provides valuable gene pools for both flooding tolerance and Phytophthora resistance. The identification of these DNA markers provides an important starting point for transferring and pyramiding genes that could contribute to sustainable improvement of soybean productivity in soils prone to flooding.
Technical Abstract: Phytophthora root rot (PRR) caused by Phytophthora sojae Kaufm. & Gerd. and flooding can limit growth and productivity, of soybean [Glycine max (L.) Merr.], especially on poorly drained soils. The primary objective of this research project was to map quantitative trait loci (QTL) associated with flooding tolerance and resistance to P. sojae. Mapping was conducted using 188 recombinant inbred lines derived from a cross between flood tolerant, PRR resistant genotype, PI 408105A, and flooding intolerant, S99-2281. A genetic linkage map consisting of 613 simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers spanning 2,346 cM was developed. Flooding tolerance was determined by measuring both plant injury and the ratio of yield under soil water logging stress compared to non water logged conditions (flooding yield index). Both Rps-gene and partial resistance were measured for each RIL using the hypocotyl and layer tests, respectively. Genomic regions on four chromosomes were associated with genetic control of decreased plant injury and higher yield under flooded conditions. Two of these regions, one near markers Sct_033 and BARC-024569-04982 on chromosome (Chr.) 13 and one near BARC-016279-02316 on Chr. 11 were associated with partial resistance to P. sojae. This study indicates that genes for both flooding tolerance and resistance to P. sojae are necessary to reduce injury and yield loss of soybean in intermitently wet soil.