Kovaleva L V, Zakharova E V, Voronkov A S, Timofeeva G V
Ontogenez. 2017 Mar-Apr;48(2):140-8.
As established by us earlier, ethylene behaves as a regulator of germination, development, and growth of male gametophyte during the progamic phase of fertilization. However, the mechanisms of the regulation of these processes remain so far unstudied. It is believed that the main factor providing variety of the ethylene responses is its interaction with other phytohormones. According to our working hypothesis, ethylene controls germination of pollen grains (PGs) and growth of pollen tubes (PTs) by interacting with auxin, which, as the available data indicate, is likely a key regulator of plant cell polarization and morphogenesis and one of the factors modulating the biosynthesis of ethylene at the level of ACC-synthase gene expression. In the present work, on germinating in vitro male gametophyte and the pollen-stigma system for petunia (Petunia hybrida L.) effects of phytohormones (ethylene and IAA) and known blockers repressing ethylene reception (1-methylcyclopropene, 1-MCP), the synthesis of ACC (amino oxyacetic acid, AOA) and transport IAA (triyodbenzoynaya acid, TYBA) on PGs germination, PTs growth and the synthesis of ACC were investigated. According to the data obtained, exogenous ethylene and IAA stimulated both PGs germination and PTs growth. 1-MCP and TYBA completely inhibited the first process, whereas IAA abolished the inhibitory action of 1-MCP and AOA on both the above processes. Etrel only partially weakened the inhibitory effect of TYBA. Examination of ACC synthesis modulation with AOA showed that IAA does not affect the level of ACC in germinating in vitro male gametophyte and nonpollinated stigmas, while this phytohormone insignificantly raised the level of ACC and abolished the inhibitory effect of AOA on its synthesis in the pollenstigma system. Pollination of stigmas with the pollen preliminarily treated with 1-MCP led to 2.5-fold decline in both the rate of PT growth and the level of ACC. At the same time, IAA abolished the inhibitory action of 1-MCP recovering the synthesis of ACC and growth of PTs to the control values. All these results, taken together, provide evidence for the interaction of the signal transduction pathways of ethylene and auxin at the level of ACC biosynthesis in the course of germination and growth of petunia male gametophyte during the progamic phase of fertilization.
正如我们之前所证实的，在受精的配子体前期，乙烯作为雄配子体萌发、发育和生长的调节因子发挥作用。然而，这些过程的调节机制至今仍未得到研究。据信，导致乙烯反应多样性的主要因素是其与其他植物激素的相互作用。根据我们的工作假说，乙烯通过与生长素相互作用来控制花粉粒（PGs）的萌发和花粉管（PTs）的生长，现有数据表明，生长素可能是植物细胞极化和形态发生的关键调节因子，也是在ACC合成酶基因表达水平上调节乙烯生物合成的因素之一。在本研究中，针对矮牵牛（Petunia hybrida L.）的雄配子体和花粉 - 柱头系统进行体外萌发实验，研究了植物激素（乙烯和吲哚 - 3 - 乙酸，IAA）以及已知的抑制乙烯受体的阻滞剂（1 - 甲基环丙烯，1 - MCP）、ACC合成抑制剂（氨基氧乙酸，AOA）和IAA运输抑制剂（三碘苯甲酸，TYBA）对PGs萌发、PTs生长以及ACC合成的影响。根据所得数据可知，外源乙烯和IAA均能刺激PGs萌发和PTs生长。1 - MCP和TYBA完全抑制了前一个过程，而IAA消除了1 - MCP和AOA对上述两个过程的抑制作用。乙烯利仅部分减弱了TYBA的抑制作用。用AOA检测ACC合成调节发现，IAA不影响体外萌发的雄配子体和未授粉柱头中ACC的水平，但这种植物激素能略微提高ACC水平，并消除AOA对花粉 - 柱头系统中ACC合成的抑制作用。用1 - MCP预处理过的花粉对柱头授粉，导致PT生长速率和ACC水平均下降了2.5倍。同时，IAA消除了1 - MCP的抑制作用，使ACC合成和PT生长恢复到对照值。综上所述，所有这些结果为在矮牵牛雄配子体受精的配子体前期萌发和生长过程中，乙烯和生长素信号转导途径在ACC生物合成水平上的相互作用提供了证据。
