Development and Characterization of Near-Isogenic Lines Derived from Synthetic Wheat Revealing the 2 kb Insertion in the PPD-D1 Gene Responsible for Heading Delay and Grain Number Improvement

Shunzong Ning，Shengke Li，Kai Xu，Dongmei Liu，Li Ma，Chunfang Ma，Ming Hao，Lianquan Zhang，Wenjie Chen，Bo Zhang，Yun Jiang，Lin Huang，Xuejiao Chen，Bo Jiang，Zhongwei Yuan and Dengcai Liu

Spikelet number and grain number per spike are two crucial and correlated traits for grain yield in wheat.Photoperiod-1 (Ppd-1) is a key regulator of inflorescence architecture and spikelet formation in wheat. In this study, near-isogenic lines derived from the cross of a synthetic hexaploid wheat and commercial cultivars generated by double top-cross and two-phase selection were evaluated for the number of days to heading and other agronomic traits. The results showed that heading time segregation was conferred by a single incomplete dominant genePPD-D1, and the 2 kb insertion in the promoter region was responsible for the delay in heading. Meanwhile, slightly delayed heading plants and later heading plants obviously have advantages in grain number and spikelet number of the main spike compared with early heading plants. Utilization ofPPD-D1photoperiod sensitivity phenotype as a potential means to increase wheat yield potential.