以脐橙早熟芽变及其早熟性状回复型为材料探究柑橘早熟性状形成机理

选育早、晚熟新品种是柑橘育种的重要目标。芽变是脐橙育种的主要途径，但是其果实熟期芽变形成机制尚不清楚。项目组通过芽变选种在纽荷尔脐橙中选育了赣南早脐橙，该品种早熟特性明显，并在田间获得其早熟性状回复型材料。早熟性状回复型与赣南早脐橙具有高度相似的遗传背景，它们与纽荷尔脐橙构成了理想的果实熟期性状研究体系。以此为研究对象，先将赣南早脐橙不同组织原层细胞培养获得单细胞株系，通过鉴定其表型来确定赣南早脐橙是同质体还是嵌合体；鉴于有性繁殖植物采用BSA-seq筛选突变体性状相关基因的思路，本研究拟建立早熟性状极端表型分离群体，结合高通量基因组测序，筛选与早熟性状共分离的差异基因，进一步挖掘与熟期相关的候选基因；遗传转化山金柑进行基因功能验证。本项目的实施，将揭示赣南早脐橙早熟机理，为其大面积推广提供科学依据，本研究对深入了解非跃变型果实成熟调控机制及加快不同熟期柑橘新品种选育进程具有重要意义。

Breeding of early-ripening or late-ripening navel orange is one of the important goals of citrus breeding. Budding is the main way of navel orange breeding，but the fruit ripening period of bud formation mechanism is unclear. We have bled Gannanzao navel orange which is a new variety from Newhall navel orange bud mutation, and the new variety had a very early maturity. And then, we got two mutational branches whose early maturity character were recovered. Therefore, Gannanzao navel orange, its early-ripening reverses and Newhall navel orange as materials will be formed a complete research system for Citrus fruit ripening mechanism. Gannanzao navel orange, its early-ripening reverses and Newhall navel orange were taken as research objects in this project. By culturing and regenerating protoplast cells of apical meristem from Gannanzao navel orange, the phenotype of regenerated plants is identified to determine whether the bud of Gannanzao navel orange is homozygotes or chimeras, and the stability of the bud is evaluated. In view of the idea of using BSA SEQ to screen genes related to mutant characters in sexual reproduction plants，by establishing an extreme phenotypic segregation population of early maturity traits and combining with high-throughput genome re-sequencing technology, differentially segregated genes with early maturity traits will be screened, and candidate genes related to maturity traits will be further excavated. The genetic transformation of Fortunella hindsii Swingle was carried out to verify the gene function. Combining the above, the formation mechanism of early maturity traits of Gannanzao navel orange will be discussed. This project not only provides scientific basis for large-scale planting of Gannanzao navel orange, but also has great significance for the development of molecular markers for ripening of Citrus, in-depth understanding of the ripening regulation mechanism of non-climacteric fruits and breeding more new citrus varieties for early-ripening or late-ripening varieties.