Li Fenfen, Jia Yanhua, Zhou Shengen, Chen Xinyu, Xie Qiaoli, Hu Zongli, Chen Guoping
Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, PR China.
J Plant Physiol. 2022 May;272:153687. doi: 10.1016/j.jplph.2022.153687. Epub 2022 Mar 29.
MADS-domain transcription factors have been identified as key regulators involved in proper flower and fruit development in angiosperms. As members of the MADS-box subfamily, B (B) genes have been observed to play an important role during the evolution of the reproductive organs in seed plants. However, their effects on reproductive development in fruit crops, such as tomato (Solanum lycopersicum), remain unclear. Here, we found that SlMBP22 overexpression (SlMBP22-OE) resulted in considerable alterations in floral morphology and affected the expression levels of several floral homeotic genes. Further analysis by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays demonstrated that SlMBP22 forms dimers with class A protein MACROCALYX (MC) and SEPALLATA (SEP) floral homeotic proteins TM5 and TM29, respectively. In addition, pollen viability and cross-fertilization assays suggested that the defect in female reproductive development was responsible for the infertility phenotype observed in the strong overexpression transgenic plants. Transgenic fruits with mild overexpression exhibited reduced size as a result of reduced cell expansion, rather than impaired cell division. Additionally, SlMBP22 overexpression in tomato not only affected proanthocyanidin (PA) accumulation but also altered seed dormancy. Taken together, these findings may provide new insights into the knowledge of B MADS-box genes in flower and fruit development in tomato.
MADS结构域转录因子已被确定为参与被子植物花和果实正常发育的关键调节因子。作为MADS盒亚家族的成员，B类基因在种子植物生殖器官的进化过程中发挥了重要作用。然而，它们对番茄（Solanum lycopersicum）等水果作物生殖发育的影响仍不清楚。在这里，我们发现SlMBP22过表达（SlMBP22-OE）导致花形态发生显著改变，并影响了几个花同源异型基因的表达水平。通过酵母双杂交（Y2H）和双分子荧光互补（BiFC）分析进一步表明，SlMBP22分别与A类蛋白大萼片（MC）和SEPALLATA（SEP）花同源异型蛋白TM5和TM29形成二聚体。此外，花粉活力和异花授粉试验表明，雌性生殖发育缺陷是强过表达转基因植物中观察到的不育表型的原因。轻度过表达的转基因果实由于细胞扩张减少而不是细胞分裂受损，其大小减小。此外，番茄中SlMBP22过表达不仅影响原花青素（PA）积累，还改变种子休眠。综上所述，这些发现可能为了解B类MADS盒基因在番茄花和果实发育中的作用提供新的见解。
