胡杨PeAPY1和PePY2在提高植物抗旱耐盐性上的功能解析

Functional Analysis of Populus euphratica PeAPY1 and PePY2 in Enhancing Salt and Drought Tolerance

胡杨(Populus euphratica Oliv.)是典型的抗旱耐盐树种,广泛用于干旱盐碱地带的造林绿化。本实验室前期研究结果表明,盐胁迫下胡杨腺苷三磷酸双磷酸水解酶(Apyrase)基因(PeAPY)的转录水平上调,表明该基因可能在胡杨的抗盐性功能上发挥作用。已有研究证明APY是水解eATP的关键酶,而eATP是植物细胞重要的信使分子,调控植物的生长发育及抗性反应。本研究以PeAPY过表达拟南芥株系、拟南芥apy1、apy2突变体和野生型拟南芥为实验材料,分析了胡杨PeAPY对植物抗旱和耐盐能力的影响。研究结果表明,PeAPY1和PeAPY2转基因株系的抗旱性明显提高,这可能与PeAPY1和PeAPY2过表达减少了叶片表皮的气孔密度,降低了叶片的失水速率,从而提高了植株的保水能力有关。此外,我们还发现PeAPY1和PeAPY2转基因株系耐盐能力有所提高:在盐胁迫条件下,过表达PeAPY1和PeAPY2转基因植物的种子萌发率和生长、成活率均明显高于突变体apy1、apy2和野生型拟南芥(NaCl处理的浓度分别为0,50 mmol/L,100 mmol/L,150 mmol/L,200 mmol/L)。这可能是由于盐处理条件下,PeAPY通过降低盐诱导的eATP浓度,阻止了eATP诱导的细胞凋亡。综上所述,胡杨PeAPY的过表达能够提高植物对盐胁迫、干旱胁迫的耐受性,PeAPY对eATP浓度调控及其对植物抗逆性的具体机制有待进一步研究。

Being as a salt- and drought-tolerant woody plants, Populus euphratica is a valuable tree species used for afforestation on saline and alkaline desert sites. We have previously shown that Populus euphratica apyrase gene, PeAPY, was markedly upregulated under NaCl treatment. This indicates that PeAPY plays an important role in Populus euphratica adaptation to saline environments. Apyrase is the key enzyme to hydrolyze ATP in the extracellular space. Extracellular ATP（eATP） serves as a crucial signal component regulating plant growth, development and the response to adverse conditions. The object of this study was to explore the role of PeAPY in salt and drought tolerance. Compared to the wildtype Arabidopsis and apy1, apy2 mutants, PeAPY1- and PeAPY2-transgenic plants exhibited a higher ability to drought stress tolerance. This is due to the reduced density of stomata in the leaf surface in transgenic Arabidopsis. The less number of stomata resulted in a water loss reduction under air-drying conditions, which benefits transgenic plants to retain water status under drought stress. Overexpression of PeAPY1 and PeAPY2 also increased salt tolerance of transgenic plants. PeAPY1- and PeAPY2-transgenic plants exhibited greater germination rate, root and shoot growth, and survival rate during the period of salt treat ment（NaCl saline series were 0, 50 mmol/L, 100 mmol/L, 150 mmol/L, and 200 mmol/L）. This is presumably due to the PeAPY reduction of salt-elicited eATP, which blocks the eATP-induced cell death in salt-treated plants.Collectively, we conclude that the overexpression of PeAPY1 and PeAPY2 increased the drought and salt tolerance of transgenic Arabidopsis. The correlation between PeAPY and eATP concentration, and the relevance to stress tolerance needs further investigation.