Expression of ROP/RAC GTPase genes in postharvest loquat fruit in association with senescence and cold regulated lignification
Expression of ROP/RAC GTPase genes in postharvest loquat fruit in association with senescence and cold regulated lignification
复制标题
采后枇杷果实ROP/RAC GTPase基因表达与衰老及冷调控木质化的关系
DOI：
10.1016/j.postharvbio.2009.05.009
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发表时间：
2009-10-01
影响因子：
7
通讯作者：
Chen, Kunsong
中科院分区：
文献类型：
--
作者：
Jin, Weiwei;Xu, Changjie;Chen, Kunsong
ROP/RAC GTP酶调控多种发育过程，在植物防御反应中发挥重要作用。最近，在水稻、百日菊、棉花和桉树中发现了与木质化或次生细胞壁形成相关的ROP成员。本研究旨在探讨不同温度下，果肉木质化与果肉木质化之间的关系。从‘洛阳青’(LYQ)果实中分离到4个ROP基因片段EjROP1.1、EjROP1.2、EjROP2和EjROP3，它们与其他植物中已知的ROP序列的核苷酸同源性均在80%以上。序列分析表明EjROP1.1、EjROP2和EjROP3可能具有功能，而EjROP1.2可能是显性负性的，因此可能是ROP信号转导的负调控因子。EjROP1.2的C末端突变可能是由于与EjROP1.1的核苷酸序列的65bp缺失所致。EjROP1.1的表达增加。EjROP2和EjROP3在20℃下贮藏的前4或6天观察到，并与果肉硬度的增加呈正相关。EjROP1.2的表达在20℃下持续较低，但在6 h内迅速诱导，在0℃下表达，24 h内增加约20倍，在5℃下也能诱导表达，但没有0℃下诱导那么强烈，果实在5℃到0℃之间的转移重新刺激了EjROP1.2的表达。讨论了EjROPs在衰老和冷调节木质化过程中的可能作用，并认为三种功能EjROPs和负调控因子EjROP1.2的同时表达对于维持ROP变阻器以保护细胞免受过度木质化具有重要意义。据我们所知，这是第一次关于缺失突变导致的显性-负性ROP的研究，并且ROP对低温有反应。(C)2009爱思唯尔B.V.保留所有权利。
ROP/RAC GTPases regulate various development processes and play important roles in plant defense responses. Recently, lignification or secondary cell wall formation related ROP members were reported in rice, zinnia, cotton and Eucalyptus. The present study aimed to investigate the possible association of loquat ROPs with flesh lignification under different temperatures. Four ROP cDNA fragments, EjROP1.1, EjROP1.2, EjROP2 and EjROP3, were isolated from 'Luoyangqing'(LYQ) loquat fruit, and all of them shared over 80% nucleotide identity with known ROPs from other plants. Sequence analysis revealed that EjROP1.1, EjROP2 and EjROP3 might be functional while EjROP1.2, with mutated C-terminal resulted from a 65 bp deletion in the corresponding nucleotide sequence as compared with EjROP1.1, might be dominant-negative and consequently act as a negative regulator of ROP signal transduction. Increase in expression of EjROP1.1. EjROP2 and EjROP3 was observed during first 4 or 6d of storage at 20 degrees C and was positively correlated with the increase in flesh firmness. Expression of EjROP1.2 was constantly low under 20 degrees C but was quickly, within 6 h, induced under 0 degrees C, and it increased by about 20 times within 24 h. The expression was induced under 5 degrees C as well but not so strong as that under 0 degrees C, and transfer of fruit from 5 degrees C to 0 degrees C re-stimulated the expression. The possible roles of EjROPs played during senescence and cold regulated lignification was discussed, and the simultaneous increase in the expression of three functional EjROPs and the negative regulator EjROP1.2 was suggested to be important for maintaining a ROP rheostat to protect cells from excessive lignification. To our knowledge, this is the first study on a dominant-negative ROP resulted from a deletion mutation, and a ROP responded to low temperature. (C) 2009 Elsevier B.V. All rights reserved.