QTL Mapping Of Root And Mycorrhizal Infection Traits In Soybean With Recombined Inbred Lines

Soybean(Glycine Max(L.) Merr) is an important source of protein and oil for human beings. The root system is a vital organ of plants for water and nutrients acquisition, and developed root system is more advantageous to the growth of soybean. In order to adapt to change of soils, water and nutrition status, root morphology, architecture and other traits are accordingly changed in plants during the biological evolution. Most of the nutrients are taken by roots from soils, and root symbiosis with mycorrhizal fungi can increase nutrient acquisition. Therefore, genetic improvement for root traits is an important developing trend, and QTL mapping of root traits using recombined inbred lines is extremely important research technique. In this study, QTL mapping for root traits, mycorrhizal infection traits, nitrogen and phosphorus(P) content, and seed yield were carried out using recombinant inbred lines previously build from BX10 and BD2, aided by 435 DNA markers, and 296 pairs of SSR primers in 41 soybean linkage groups. The main results and conclusions are as follows:1. Fifteen traits related to root morphology and architecture, mycorrhizal infection, plant nutritional status and yield were investigated in the field. Among them, the segregations of 12 traits, except root volume, arbuscular abundance of primary root, and vesicle abundance of primary root, in the RIL population accorded with normal distribution, and were used for QTL mapping2. QTL mapping analysis were carried out using 12 traits including root morphology and architecture, mycorrhizal infection, plant nutritional status and yield. Thirty loci associated with these traits were identified, of which 17 QTLs were under high P condition, and 13 under low P condition. Only one co-location of QTL was identified on linkage L for root dry weight and nitrogen content under high P conditions.3. Seven QTLs for the seed weight, nitrogen and phosphorus contents were identified. Among them, the seed weight had 3 QTLs, including 2 under low P condition, 1 under high P level. Nitrogen content had 3 QTLs and P content had 1 QTL at high P treatment.4. Eighteen QTLs for root traits were identified, including 4 QTLs for root dry biomass at high P, 3 QTLs at low P and 1 QTL at high P for primary root length, 1 QTL at low P and 2 QTLs at high P for root width, 1 QTL at low P and 2 QTLs at high P for the ratio of primary root length and width, 1 QTL at low P and 1 QTL at high P for total root length, and 1 QTL for root surface area and 1 QTL for root average diameter at low P.5. Mycorrhizal infection rate of lateral roots had three QTLs, including 2 located in G and H-2 linkage groups at high P level, respectively, and 1 located in linkage C1-1 at low P level. Mycorrhizal infection rate of primary roots had two QTLs, located in A1 and N linkage groups under low P condition, respectively, and no loci were found at high P.In summary, QTL mapping analyses were carried out using root traits and the related infection traits of mycorrhizal fungi, which were the important member of the root symbiosis. Some important QTLs related to mycorrhizal infection were identified, which provides basic data for the genetic improvement of root system and mycorrhizal symbiosis.