Mo Xiaoli, Wang Yihao, Huang Yahui, Zeng Zhen, Yan Changyu
College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Plants (Basel). 2025 Jul 5;14(13):2061. doi: 10.3390/plants14132061.
The undertaking of distant hybridization holds paramount significance for the innovation of tea germplasm resources and the cultivation of superior, specialized tea varieties. However, challenges manifest during the process of tea plant distant hybridization breeding, with reproductive barriers impeding the successful acquisition of hybrid progeny; the precise stages at which these barriers occur remain unclear. In this study, utilizing cv. Jinxuan as the maternal parent, as well as Chang and cv. Yinghong No.9 as the paternal parents, interspecific distant hybridization (DH) and intraspecific hybridization (IH) were conducted. The investigation involved the observation of pollen germination and pollen tube behavior on the stigma, the scrutiny of the developmental dynamics of the ovary post-hybridization, and the examination of the stages and reasons for reproductive disorders during tea tree distant hybridization. The findings indicate that both IH and DH exhibit pre-fertilization barriers. The pre-embryonic development of hybrids obtained from DH is normal, but there is a significant fruit drop during the stage of fruit development. The germination rate of mature seeds obtained from DH is low, and there are pronounced post-fertilization disorders, which are the primary reasons for the difficulty in achieving successful tea plant distant hybridization. An analysis of the genetic variation in phenotypes and chemical components in the progeny after distant hybridization revealed widespread variation and rich genetic diversity. The identification of progeny with a high amino acid and caffeine content holds promise for future production and breeding, providing valuable theoretical references for the selection of parents in the creation of low-caffeine-content tea germplasm resources.
远缘杂交对于茶树种质资源创新和优良、专用茶树品种培育具有至关重要的意义。然而，茶树远缘杂交育种过程中存在挑战，生殖障碍阻碍了杂交后代的成功获得；这些障碍发生的确切阶段尚不清楚。本研究以金萱品种为母本，以长叶白毫和英红九号品种为父本，进行了种间远缘杂交（DH）和种内杂交（IH）。调查内容包括观察花粉在柱头上的萌发和花粉管行为、杂交后子房发育动态的细察以及茶树远缘杂交过程中生殖障碍的阶段和原因探究。结果表明，种内杂交和种间远缘杂交均表现出受精前障碍。种间远缘杂交获得的杂种胚前发育正常，但在果实发育阶段出现显著落果现象。种间远缘杂交获得的成熟种子发芽率低，且存在明显的受精后障碍，这是茶树远缘杂交难以成功的主要原因。对远缘杂交后代的表型和化学成分遗传变异分析表明，后代存在广泛变异和丰富的遗传多样性。鉴定出高氨基酸和咖啡因含量的后代对未来生产和育种具有重要意义，为低咖啡因含量茶树种质资源创制中亲本选择提供了有价值的理论参考。
