Phenotypic and genetic variation in phosphorus-deficiency-tolerance traits in Chinese wheat landraces.

BACKGROUND: Phosphorus deficiency is a major limiting factors for affecting crop production globally. To understand the genetic variation of phosphorus-deficiency-tolerance, a total of 15 seedling traits were evaluated among 707 Chinese wheat landraces under application of phosphorus (AP) and non-application of phosphorus (NP). A total of 18,594 single-nucleotide polymorphisms and 38,678 diversity arrays technology sequencing markers were used to detect marker-trait associations under AP and NP. RESULTS: Top ten genotypes with extremely tolerance and bottommost ten genotypes with extremely sensitivity were selected from 707 Chinese wheat landraces for future breeding and genetic analysis. A total of 55 significant markers (81 marker-trait associations) for 13 traits by both CMLM and SUPER method. These were distributed on chromosomes 1A, 1B, 2A, 2B, 2D, 3A, 4B, 5A, 5B, 6A, 6B, 6D, 7A and 7B. Considering the linkage disequilibrium decay distance, 25 and 12 quantitative trait loci (QTL) were detected under AP and NP, respectively (9 QTL were specific to NP). CONCLUSIONS: The extremely tolerant landraces could be used for breeding phosphorus-deficiency-tolerant cultivars. The QTL could be useful in wheat breeding through marker-assisted selection. Our findings provide new insight into the genetic analysis of P-deficiency-tolerance, and will be helpful for breeding P-deficiency-tolerant cultivars.

Quantitative trait loci analysis of root traits under phosphorus deficiency at the seedling stage in wheat.

Deficiency of available phosphorus (P) in soil limits wheat production and creates a need to develop P-deficiency-tolerant cultivars. Plant roots, important organs for absorbing nutrients and synthesizing growth regulators, are good candidates for P-efficiency screening. In this study, we evaluated five root traits under hydroponic culture conditions either with (AP) or without (NP) applied P in a recombinant inbred line population (H461/CM107) of Triticum aestivum L. at the seedling stage. Four significant quantitative trait loci (QTL) were detected, on chromosomes 1D, 2D, 3D, and 7D in NP-treated plants, explaining up to 13.0%, 11.0%, 14.4%, and 12.8% of the phenotypic variance, respectively. Among these QTL, Qrt.sicau-3D and Qrt.sicau-7D showed pleiotropic and additive effects. All QTL were found to be novel. The diversity array technology markers flanking the QTL were converted to simple sequence repeat markers that can be deployed in future genetic studies of P deficiency. These QTL lead to an increase in root biomass and respond to P-deficiency stress; these characteristics are crucial to improve root traits for breeding or further investigation of the gene(s) involved in P-deficiency tolerance.

Identification of major quantitative trait loci for root diameter in synthetic hexaploid wheat under phosphorus-deficient conditions.

Synthetic hexaploid wheat (SHW) possesses numerous genes for resistance to stress, including phosphorus (P) deficiency. Root diameter (RDM) plays an important role in P-deficiency tolerance, but information related to SHW is still limited. Thus, the objective of this study was to investigate the genetic architecture of RDM in SHW under P-deficient conditions. To this end, we measured the RDM of 138 F9 recombinant inbred lines derived from an F2 population of a synthetic hexaploid wheat line (SHW-L1) and a common wheat line (Chuanmai32) under two P conditions, P sufficiency (PS) and P deficiency (PD), and mapped quantitative trait loci (QTL) for RDM using an enriched high-density genetic map, containing 120,370 single nucleotide polymorphisms, 733 diversity arrays technology markers, and 119 simple sequence repeats. We identified seven RDM QTL for P-deficiency tolerance that individually explained 11-14.7% of the phenotypic variation. Five putative candidate genes involved in root composition, energy supply, and defense response were predicted. Overall, our results provided essential information for cloning genes related to P-deficiency tolerance in common wheat that might help in breeding P-deficiency-tolerant wheat cultivars.