油菜素内酯合成酶基因DAS5促进杨树生长及提高抗旱性的作用

以河北杨(Populus hopeiensis)为材料, 研究拟南芥(Arabidopsis thaliana)油菜素内酯(BR)生物合成酶基因DAS5对其生长表型、生物量及抗旱性的影响。结果表明: (1) 转DAS5基因河北杨植株的根长、地径、叶柄及叶片长度均显著大于野生型植株, 且地上、地下部分干重及根冠比显著高于野生型, 其拥有发达的根系; (2) 在干旱胁迫下, 转DAS5基因河北杨植株失水褪绿速度较野生型植株缓慢, 在复水后转基因植株能够较早较好地恢复活力, 萌发较多的新幼芽且长势良好; (3)控水期间, 转基因河北杨的相对生长率显著高于野生型, 且随着干旱胁迫程度的加剧, 其可溶性糖含量、游离脯氨酸含量、过氧化氢酶(CAT)活性、超氧化物歧化酶(SOD)活性均显著高于野生型。实验结果表明, 与野生型相比, 转基因植株具有较高的生长量与较强的抗干旱胁迫能力, 说明来自拟南芥的BR生物合成酶基因DAS5可以显著增加河北杨的生长量并在抵御干旱胁迫机制中发挥重要作用。

Effect of the Brassinosteroid Biosynthetic Enzyme DAS5 on Growth and Drought Resistance in Poplar

We studied the effect of the brassinosteroid biosynthetic enzyme DAS5 on growth, biomass and drought resistance of Populus hopeiensis. The ground diameter, root length, petiole length, leaf length, dry weight of shoot and root, ratio of root to shoot of transgenic P. hopeiensis plants were bigger and higher than those of non-transgenic plants. Under drought stress, dehydration and chlorina were slower in leaves of transgenic than wild-type seedlings, and transgenic seedlings showed stronger recovery after rehydration, with more new and well-growing buds. The relative growth rate was higher for transgenic than wild-type seedlings under water-controlled conditions. Soluble sugar and proline content as well as catalase and superoxide dismutase activity were significantly higher in transgenic than non-transgenic plants as drought conditions worsened. Thus, the growth of the transgenic plants and their resistance to drought stress was better than the wild types. The brassinosteroid biosynthetic enzyme DAS5 from Arabidopsis could promote plant growth and play an important role in resistance against drought stress of P. hopeiensis.