Functional marker CAPS-799 of the TaPHT1;9-4B gene is useful for screening phosphorus-efficient wheat cultivars

Context: In our previous study, TaPHT1;9-4B, one key high-affinity Pi transporter, was found to greatly contribute to Pi acquisition and transportation, and its functional marker CAPS-799 was subsequently developed to identify its Pi-efficient elite haplotype. Objective: The study aimed to screen a varieties of wheat cultivars by using the above CAPS-799, identify its Pi-efficient elite haplotype cultivars, and reveal its physiological mechanism. Methods: Successive two-year field experiments without Pi fertilizer supply, and hydroponic experiment with low Pi (10 μM) were performed. P concentrations, biomasses, grain yields, yield components, root growth parameters, and TaPHT1;9-4B transcript levels were measured. Total P accumulation and transport efficiency, and the relative growth rates were calculated. Results: Eight Pi-efficient wheat cultivars (Hap3 haplotype) were screened out by using the CAPS-799 from 80 modern major cultivars, and in successive two-year field experiments, their grain yields, spike numbers, P absorption and transport efficiencies were significantly higher than those of Non-Hap3 haplotypes (Hap1, 2 and 4) under no Pi fertilizer supply condition, and therefore, these eight cultivars belonged to Pi-efficient elite haplotype. TaPHT1;9-4B transcript levels in roots at the early stage of grain filling period in field experiment, and the relative growth rates of total root surface areas, volumes and mean root diameters of Hap3 cultivars in hydroponic experiment, were markedly higher than other haplotypes. Conclusions: CAPS-799 was a useful functional marker for screening Pi-efficient wheat cultivars, and its Pi-efficient wheat cultivars were characterized with higher TaPHT1;9-4B transcript levels and more roots. Implications: CAPS-799 will be used to screen or develop Pi-efficient wheat cultivars.