College of Agriculture and Biotechnology, China Agricultural University, Beijing 100193, PR China.
Plant Physiol Biochem. 2013 Dec;73:412-9. doi: 10.1016/j.plaphy.2013.10.020. Epub 2013 Oct 29.
As an important regulator, ethylene inhibits root growth and development in plants. To determine the mechanism of ethylene on root elongation growth and lateral root formation, ethylene-induced lignification and cell wall-degrading enzymes in the roots of mungbean sprouts were tested. We initially observed that primary root elongation and lateral root numbers were inhibited, while lignin content was enhanced by ethephon (ETH). Cell wall remolding proteins, polygalacturonase (PG) and carboxymethyl cellulose (Cx) activities were reduced, but α-expansins and xyloglucan endotransglucosylases/hydrolases (XTH) were enhanced by ETH. The promotion in lignin production was correlated with changes in activities of key lignin biosynthesis enzymes and hydrogen peroxide (H2O2) content. These actions induced by ETH were altered via treatment with an ethylene perception antagonist (Ag+). We subsequently demonstrated that the role of endogenous ethylene in regulating root elongation growth and lateral root formation were correlated with lignification and cell wall-degrading enzymes, respectively. These results suggested that the ethylene-regulated inhibition of primary root elongation growth was caused by an increase in lignification that reinforced the cell wall and shortened root length, and the suppression of lateral root formation was linked to activities of PG, Cx, α-expansins and XTH.
作为一种重要的调节剂，乙烯抑制植物的根生长和发育。为了确定乙烯对根伸长生长和侧根形成的作用机制，测试了乙烯诱导绿豆芽根中木质素化和细胞壁降解酶。我们最初观察到，乙烯利（ETH）抑制主根伸长和侧根数，同时增加木质素含量。细胞壁重塑蛋白，多聚半乳糖醛酸酶（PG）和羧甲基纤维素（Cx）活性降低，但α-扩张蛋白和木葡聚糖内转糖苷酶/水解酶（XTH）增加。木质素产量的增加与关键木质素生物合成酶活性和过氧化氢（H2O2）含量的变化相关。这些由 ETH 诱导的作用通过用乙烯感知拮抗剂（Ag+）处理而改变。随后，我们证明了内源乙烯在调节根伸长生长和侧根形成中的作用分别与木质素化和细胞壁降解酶相关。这些结果表明，乙烯调节的主根伸长生长抑制是由于木质素化增加导致细胞壁加强和根长缩短引起的，而侧根形成的抑制与 PG、Cx、α-扩张蛋白和 XTH 的活性有关。
