Soybean is one of the world’s most valuable crops. In 2021, the U.S. soybean crop was valued at $57.5 billion. Unfortunately, extreme weather conditions including prolonged drought and frequent floods significantly suppress soybean production. Together these two stresses can suppress soybean yield valued at over $1 billion. The goal of this project is to develop soybean cultivars that can perform under drought and flood conditions. To reach the goal, we proposed to introgress four genetic loci including (i) two drought tolerance quantitative trait loci (QTL) explaining close to 50% of the genetic variation for drought tolerance and (ii) two flood tolerance QTL explaining 20% of the variation for flood tolerance into four elite soybean cultivars of different maturity groups (MGs), ideal for growing in Minnesota, Iowa, Illinois, Indiana, Kansas, and Missouri. We proposed to introgress the four QTL individually into each cultivar. Eventually, we proposed pyramided all four QTL through hybridization. A molecular marker-assisted back-crossing method was considered to apply to expedite the cultivars with drought and flood tolerance attributes. The two deliverables of this project are: (i) Generate four drought-tolerant cultivars. (ii) Generate four flood-tolerant cultivars. We selected four cultivars of the maturity groups (MGs), MG 1, MG 1.5, MG 3 and MG 4 ideal for growing in Minnesota, Iowa, Illinois, Indiana, Kansas, and Missouri where soybean is mostly grown as a rainfed crop. The four cultivars were hybridized to each of the four donor cultivars presented and F1 hybrids were generated. The true F1s were selected through molecular marker analyses and hybridized to respective recurrent parent cultivars to generate the BC1F1 generations. The true BC1F1s were then selected through molecular marker analyses and used to generate the BC2F1 generations. We have developed a SNP panel for selecting the drought and flood tolerance QTL with minimal linked undesirable DNA from the donor parents. The SNP panel will be used to identify desirable genotypes from large segregating populations that will be generated when we will start to pyramid the target genes through hybridization of near isogenic recurrent cultivars each carrying one or two drought or a flood tolerance QTL. We have selected four drought tolerance and two flood tolerance QTL for introgressing into the four cultivars.

This project allowed us stacking four drought tolerance and two flood tolerance genetic in four soybean cultivars with different maturity groups for securing soybean production in soybean growing areas that are prone to frequent drought and flood, two serious abiotic stresses that could suppress soybean yield valued over $1 billion. The outcomes of this project are expected to reduce yield suppression from these two abiotic stresses and enhanced farmers profits by hundreds of millions of dollars. Furthermore, the outcomes will contribute significantly to the sustainability of soybean production and soybean industry.