Yamaguchi Aya, Soga Kouichi, Wakabayashi Kazuyuki, Hoson Takayuki
Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan.
Department of Biology, Graduate School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan.
Plants (Basel). 2023 Jan 12;12(2):367. doi: 10.3390/plants12020367.
The exogenous application of ethylene or 1-aminocyclopropane-1-carboxylic acid (ACC), the biosynthetic precursor for ethylene, to plants decreases the capacity of the cell wall to extend, thereby inhibiting stem elongation. In this study, the mechanism by which the extensibility of cell walls decreases in ACC-treated azuki bean epicotyls was studied. ACC decreased the total extensibility of cell walls, and such a decrease was due to the decrease in irreversible extensibility. ACC increased the molecular mass of xyloglucans but decreased the activity of xyloglucan-degrading enzymes. The expression of , which only exhibits hydrolase activity toward xyloglucans, was downregulated by ACC treatment, whereas that of or , which exhibits only transglucosylase activity toward xyloglucans, was not affected by ACC treatment. The suppression of xyloglucan-degrading activity by downregulating expression may be responsible for the increase in the molecular mass of xyloglucan. Our results suggest that the modification of xyloglucan metabolism is necessary to decrease cell wall extensibility, thereby inhibiting the elongation growth of epicotyls in ACC-treated azuki bean seedlings.
向植物外源施加乙烯或乙烯的生物合成前体1-氨基环丙烷-1-羧酸（ACC），会降低细胞壁的伸展能力，从而抑制茎的伸长。在本研究中，对ACC处理的赤小豆上胚轴中细胞壁伸展性降低的机制进行了研究。ACC降低了细胞壁的总伸展性，这种降低是由于不可逆伸展性的降低所致。ACC增加了木葡聚糖的分子量，但降低了木葡聚糖降解酶的活性。仅对木葡聚糖表现出水解酶活性的 的表达受到ACC处理的下调，而仅对木葡聚糖表现出转葡糖基酶活性的 或 的表达不受ACC处理的影响。通过下调 表达来抑制木葡聚糖降解活性可能是木葡聚糖分子量增加的原因。我们的结果表明，木葡聚糖代谢的改变对于降低细胞壁伸展性是必要的，从而抑制ACC处理的赤小豆幼苗上胚轴的伸长生长。
