| Phosphorus (P) is one of the most necessary nutrition elements for crop, which plays an irreplaceable role in plant growth and development. Although the total P in soil is high, it is largely unavailable for plants; because it readily forms complexes with some metal cations. Soil P deficiency is one of the major limiting factors to wheat production in many regions. Wheat (Triticum aestivum L.) is one of the major food crops in the world and in China, which plays an important role in food security. Wheat production improvement is one of the most important tasks in current agricultural production. A large number of researches indicated that different species or genotypes vary widely in their ability of P uptake and use efficiency under P-deficient conditons. Wheat with high phosphorus use efficiency can grow and develop normally under relatively low P conditions. Cultivating wheat cultivars with high P efficiency is the fundamental way to raise Puse efficiency:and exploiting low-P tolerant wheat germplasm resources is the basic of breeding wheat varieties with high P efficiency. P efficiency related traits are typical quantitative traits, which were controlled by various genes and easily affected by environment. QTL mapping of Pefficiency related traits can reveal the genetic control of wheat P use efficiency, and serve as a basis for wheat maker-assisted selection breeding with high phosphorus efficiency and cloning of high phosphorus efficiency genes.In this study,42 different wheat genotypes were used for screening of low P tolerant wheat at seedling stage in the hydroponic culture system. A recombinant inbred line (RIL) population, consisting of 182 lines derived from wheat cultivars Xiaoyan 54 and Jing 411, was used for QTL mapping of P efficiency related traits. Field trials in two successive years were conducted to investigate seven P efficiency related traits (grain phosphorus content, GPC:straw phosphorus content,grain, SPC; grain phosphorus uptake, GPU; straw phosphorus uptake, SPU; total phosphorus uptake, TPU:grain phosphorus use efficiency, GPUE; plant phosphorus use efficiency, PPUE). QTL analysis was conducted using composite interval mapping (CIM) method based on mixed linear model in two ways:with and without QTL×Environment interaction. The results are as follows:1. The 42 wheat cultivars (lines) were clustered into three large groups at euclidean distance about 6.754 by cluster analysis:low-P tolerant type, mean type and low-P sensitive. Relative shoot dry weight (RSDW) and relative shoot phosphorus use efficiency (RSPUE) were the most ideal screening indexes of low-P tolerant wheat at the seedling stage. Nine low-P tolerant wheat cultivars (lines) were detected:08B54,08B10,08B34, 08B19,08B17,08B2, Shixin 828, Shixin 733 and Kenong 199.2. A total of 57 QTLs were detected on 18 chromosomes except 2D,4A and 7B, including 23 additive QTLs (12 with positive alleles came from Xiaoyan 54,11 from Jing 411) and 17 epistatic QTLs (6 parental type> recombinant type,11 recombinant type> parental type). High P use efficiency alleles came from both the two parents. Five QTLs, which were localized on chromosomes 1A (GPPUE),2B (GPPUE),5A (GPC, PPUE) and 5B (PPUE), were detected under both the two analysis methods. Nine QTL clusters involving more than one trait were detected, which were localized on chromosomes 1A, ID,2B (2).4D,5A (2),6A and 6D. The QTL cluster on chromosome 1A involves 5 traits including GPC, GPU, TPU, GPUE and PPUE. Five QTL intervals on chromosomes 2B, 4D,5A,6A and 6D were detected to affect both GPU and GPUE. Three additive QTLs and five epistatic QTLs were with significant environmental effects. |
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