Qi Xiaoxiao, Hu Shi, Zhou Hongsheng, Liu Xing, Wang Lifen, Zhao Biying, Huang Xiaosan, Zhang Shaoling
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China; College of Agriculture, Medicine and Health, Anhui Radio and Television University, China.
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Gene. 2018 Feb 5;642:163-171. doi: 10.1016/j.gene.2017.11.018. Epub 2017 Nov 10.
MADS-box proteins have been implicated in many biological processes. However, plant MADS-box proteins functioning in floral organ abscission and the underlying physiological mechanisms remain poorly understood. Here, we report the identification and functional characterization of PsJOINTLESS isolated from 'Kuerlexiangli'. PsJOINTLESS had a complete open reading frame of 672bp, encoding a 224 amino acid peptide, and shared high sequence identities with MADS-box from other plants. PsJOINTLESS was subcellularly targeted to the nucleus, supporting its role as a transcription factor. Expression levels of PsJOINTLESS in the calyx tube were strongly induced by calyx abscission treatment at 6d after full bloom. Overexpression of PsJOINTLESS in tomato enhanced the rate of pedicel abscission rate. Of special note, the transgenic plants increased the abscission zone cell layer compared with wild type. Furthermore, the tomato transgenic lines showed thinner flower pedicels, more cell number and small pedicel cell size. The cellulase activity in pedicel abscission zone of transgenic plants was higher than that of wild type. In addition, steady-state mRNA levels of five cell wall hydrolase genes coding for either functional or regulatory proteins were induced to higher levels in the transgenic lines. These results clearly demonstrate that PsJOINTLESS may affect pedicel abscission zone development.
MADS盒蛋白参与了许多生物学过程。然而，在花器官脱落中发挥作用的植物MADS盒蛋白及其潜在的生理机制仍知之甚少。在这里，我们报告了从‘库尔勒香梨’中分离得到的PsJOINTLESS的鉴定和功能特性。PsJOINTLESS具有一个672bp的完整开放阅读框，编码一个224个氨基酸的肽段，并且与其他植物的MADS盒具有高度的序列同一性。PsJOINTLESS在亚细胞水平上定位于细胞核，这支持了它作为转录因子的作用。在盛花后6天进行萼片脱落处理，强烈诱导了PsJOINTLESS在萼筒中的表达水平。在番茄中过表达PsJOINTLESS提高了花梗脱落率。特别值得注意的是，与野生型相比，转基因植物的脱落区细胞层数增加。此外，番茄转基因株系的花梗更细，细胞数量更多，花梗细胞尺寸更小。转基因植物花梗脱落区的纤维素酶活性高于野生型。此外，编码功能蛋白或调节蛋白的五个细胞壁水解酶基因的稳态mRNA水平在转基因株系中被诱导到更高水平。这些结果清楚地表明，PsJOINTLESS可能影响花梗脱落区的发育。
