水稻细胞质雄性不育系和保持系对外源茉莉酸响应以及内源茉莉酸合成的差异

Differences of jasmonic acid sensitivity and endogenous jasmonic acid synthesis between cytoplasmic male sterile line and its maintainer line in rice

为了探索茉莉酸(jasmonic acid,JA)是否参与调控水稻细胞质雄性不育性状,以协青早A和协青早B为材料,通过分析茉莉酸甲酯(methyl jasmonate,MeJA)的生理效应,比较2种材料对于外源MeJA敏感性的差异;通过检测机械伤害和幼穗发育过程中内源JAs(JA+MeJA)含量的变化,比较它们内源JAs合成的差异。结果表明:较低浓度的外源MeJA抑制协青早A的种子萌发,但不能抑制协青早B的种子萌发;MeJA抑制水稻的第2叶生长,协青早B表现出更强的抑制效应;MeJA诱导的离体叶片衰老进程2种材料无明显差异。当水稻叶片受到机械伤害后,协青早B内JAs含量的上升幅度明显高于协青早A。而在生殖生长时期,当幼穗发育到花粉母细胞减数分裂期即协青早A花粉败育时,协青早B幼穗内的JAs含量明显高于协青早A,而在其他时期两者幼穗内JAs含量没有显著差异。结论:植物对JA的敏感性具有组织和发育时期的特异性,协青早A花粉母细胞减数分裂期内源JAs的含量低可能是导致细胞质雄性不育的原因。

In order to study the involvement of jasmonic acid（ JA） in cytoplasmic male sterility（ CMS）,cytoplasmic male sterile line Xieqingzao A（ XqzA） and its maintainer line Xieqingzao B（ XqzB） were used as materials in this study. JA-inhibited seed germination and seedling growth and JA-induced detached leaf senescence were used to compare the sensitivity of plant tissues to JA. In addition,wounding induced endogenous JA synthesis and changes of endogenous JA level during the young panicle developmental period were used to compare JA production between these two lines. Seeds of XqzA and XqzB were soaked in different concentrations of methyl jasmonate（ MeJA） solutions for 24 h. Then seeds were washed with distilled water and germinated on filter paper saturated with distilled water. We found that exogenous MeJA could inhibit seed germination in XqzA,and its effect was dose dependent. In XqzA,the germination rate of seeds soaked in 1 000 μmol·L-1MeJA was 84. 6% of that of the control. While no inhibitory effect on seed germination was observed when seeds of XqzB were soaked in MeJA at concentrations up to 1 000 μmol·L-1.These results suggested that MeJA exhibited stronger inhibition on seed germination in XqzA compared with XqzB. Supplementation of the growth medium with MeJA caused a drastic inhibition in root and seedling growth both in XqzA and XqzB. No obvious differences were found between these two lines in seminal root length and adventitious root numbers. On the other hand,a greater inhibitory effect was seen in the second leaf growth in XqzB compared with that in XqzA. The inhibitory rates of the second leaf sheath length treated with 1. 0 μmol·L-1MeJA were 86. 8% and 76. 4% in XqzA and XqzB,respectively. The same phenomenon was displayed by the second leaf blade length in both lines. These results demonstrated that XqzB conferred a greater repression effect of JA on seedling growth compared to XqzA. As to MeJA induced detached leaf senescence,no distinct difference was found between these two lines. In this study,we also found that endogenous JAs（ JA＋MeJA） content in wounded leaves were rapidly increased within 15 min after mechanical wounding in these two lines. JAs content peaked at 30 min and returned to their basal level within 360 min after wounding. Furthermore,there was a greater increase of JAs content in XqzB compared to XqzA after mechanical wounding. JAscontent in wounded leaves of XqzB was about 1. 5-fold greater than that of XqzA 30 min after wounding. In addition,during the young panicle developmental period,more JAs accumulation was noticed at pollen mother cells meiosis stage in panicle of XqzB compared with that of XqzA. JAs content was 1 120. 5 and 705. 1 ng·g-1in XqzB and XqzA,respectively. No apparent difference was seen between these two lines at other developmental stages. Interestingly,the stage at which JAs content in panicles of XqzA was lower than XqzB is the period when pollen abortion occurred in XqzA. Conclusions： These results suggest that sensitivity of the plant to JA has tissues and developmental specificity and that the lower level of JAs content in XqzA at pollen mother cells meiosis stage may contribute to the pollen abortion in XqzA.