枳是最重要的柑橘砧木之一，其多胚特性为快速生产整齐一致的砧木提供了重要保障。但对杂交育种而言，受珠心胚干扰导致杂交后很难得到有性后代，严重影响了杂交育种效率。申请人团队前期克隆了控制柑橘属和金柑属多胚性状的关键基因CitRWP，但进一步研究发现，控制枳属多胚性状的遗传位点与柑橘属、金柑属并非同一位点，其遗传基础不同。本项目拟利用早期创制的“红橘×枳”遗传群体及自然资源，结合基因组学手段定位控制枳多胚性状的候选基因，开发指示枳属多胚性状的分子标记；通过在短童期的单胚材料中超量表达和多胚材料中基因敲除，验证候选基因功能；通过筛选与关键基因互作的蛋白及上游调控因子，解析关键基因的作用机制。本项目将进一步深化对芸香科植物多胚性状遗传基础的系统认识，对柑橘等果树砧木遗传改良以及其它作物固定杂种优势具有重要应用价值。

Trifoliate orange (Poncirus trifoliata) is one of the most important rootstock of citrus, its polyembryony trait caused by apomixis provides an important guarantee for fast production of uniform rootstock. However, for cross breeding, the interference of nucellar embryos makes it difficult to obtain sexual offspring after hybridization, which seriously affects the efficiency of cross breeding. Our research group previously cloned the key gene CitRWP controlling the polyembryony trait of citrus and kumquat. But further study found that the genetic locus controlling the polyembryony trait of trifoliate orange was not the same locus as that of citrus and kumquat, and its genetic basis was different. In this proposal, we plan to use the genetic population of "red tangerine × trifoliate orange" and natural resources, combining the genomics approach, to locate candidate genes controlling polyembryony trait of trifoliate orange, and develop molecular markers indicating polyembryony trait. The candidate genes will be over-expressed in monoembrynic kumquat and knocked out in polyembryonic trifoliate orange to verify gene functions. By screening the proteins interacting with the key genes and the upstream regulatory factors, the mechanism of the key genes will be analyzed. This project will further deepen the systematic understanding of the genetic basis of polyembryonic traits in Rutaceae plants, and have important application value for the genetic improvement of rootstocks of fruit trees and fixation of heterosis in other crops.