Density-Increasing Of Genetic Map And QTL Mapping For Phosphorous Efficiency Associated Traits In Soybean [Glycine Max (L.) Merr.]

Phosphorus is an essential macro-nutriment required for plant growth and development. Although total P content in soil may be high, it is often present in unavailable forms or in forms that are only available outside of rhizosphere. This results in low availability to plants in many soils. In modern agricultural systems, P deficiency can be alleviated by fertilizer application, but there is a financial difficulty with increasing fertilizer costs for farmers, in addition inadequate practices will cause environmental problems. Release of P-efficient genotypes in crop production systems would reduce the production costs associated with P fertilizer applications, minimize environmental pollution and contribute to maintenance of world P resources globally.In this study, we used a RIL [NJ (SP) BN] population derived from an F₂, crossed between two soybean varieties, Bogao and Nanong94-156, to construct a genetic map. This map was a complement of our previous genetic map. Based on the constructed map, genetic factors contributing to P-efficiency related traits: Shoot dry weight, Root dry weight, Plant height, P use efficiency, P absorb efficiency, Chlorophyll content and Acid phosphatease activity were identified.1. Based on our previous study, we complemented 256 pairs of SSR, with total 971 pairs of markers to analyze the RIL population NJ (SP) BN. Evaluation showed that a total of 376 markers were identified as having polymorphisms between the two parents, Bogao and Nannong94-156, including 373 SSRs, and 3 phenotypic loci. The content of Bogao and Nannong94-156 contributed to the 154 lines population was about 0.493 and 0.507, respectively. The distribution of genotypic composition of the population fitted well. Genetic distances of each pair of lines were calculated by Dice's method. The result of cluster by method UPGMA showed that the population had less over presentation. In a word, the population was suit to genetic mapping and other genetic research for its well-dispersed genetic structure.2. A genetic map based on SSR markers was constructed with this population. It covered 22 linage groups and contained 306 loci including 303 SSR markers, 3 phenotypic markers. The length of the map was 3212.3cM and the average distance of loci was 11.5cM. It was easy to compare this map to soybean integrated genetic map for most markers in this map were SSRs and it fitted the integrated genetic map well both in the locations and the distances of markers.3. Twenty QTLs associated with those traits were detected, fourteen under low P condition, six under high P condition. Among those, contribution of two QTLs were high than 15%. One affected plant height under low P condition, and it was located on linkage group E. The other affected chlorophyll content under low P condition, and it was located on linkage group N. We found two colocalized QTL. One colocalized QTL located on linkage group E, and it controled shoot dry weight, root dry weight, plant height under low P condition. It also affected shoot dry weight under high P condition. Thus, we infer it may be an essential QTL for soybean growth. The other colocalized QTL was also located on linkage group E, controlling root dry weight and chlorophyll content under low P condition.