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    外源BR与IAA对欧美杨耐旱性的影响

    Effects of exogenous BR and IAA on drought tolerance of Populus deltoides × P.nigra

      摘要
    • 摘要: 为了探究外源油菜素类固醇(brassinosteroid，BR)和IAA对杨树耐旱性的影响，本文选取3种欧美杨无性系NE19、R270、107的1年生盆栽苗木，分别喷洒10 μmol/L BR和100 mg/L IAA，并同时控制土壤含水量为20%，对其进行为期15 d的干旱处理和非干旱处理，对它们的生长和生理变化进行检测。结果表明：与无激素组相比，BR与IAA均可显著提高干旱条件下3种欧美杨无性系的净光合速率(Pn)、光化学量子产量(Fv/Fm)、叶绿素含量、叶片保水能力。BR处理NE19、R270、107的Pn比非干旱组分别提高19%、60%、85%，IAA处理分别高了35%、50%、80%；对Fv/Fm，BR处理的NE19、R270、107比对照组提高了7.7%、7.5%、10.9%，而IAA组提高了7.4%、8%、11.9%。以上结果说明外源施加BR与IAA提高了欧美杨无性系的耐旱性。统计经过激素处理后的欧美杨无性系气孔指数发现，BR处理NE19、R270、107的气孔指数分别下降12.28%、25.60%、20.31%，IAA处理分别下降13.00%、13.15%、14.48%，因此我们推测施加BR和IAA，会抑制植物气孔发育以降低干旱条件下的水分消耗；通过荧光定量PCR，检测与气孔发育6个相关基因EPF1、EPF2、EPFL9、ERECTA、FAMA、SDD1的表达量特征，发现BR和IAA处理导致负调节气孔发育相关基因EPF1、EPF2、ERECTA、SDD1表达量升高，正调节气孔发育基因FAMA与EPFL9表达量下降。综上所述，植物激素BR与IAA参与欧美杨气孔发育过程，在干旱条件下通过抑制气孔发育提高欧美杨抗旱性。

       

      Abstract: In order to study the effects of exogenous BR and IAA on the drought resistance of poplar, the 1-year-old potted seedlings of three Populus deltoides × P. nigra clones, NE19, R270, and 107 were selected for 15 days of treatment and sprayed with 10 μmol/L brassinostevoid (BR) and 100 mg/L IAA. The results showed that BR and IAA significantly improved the net photosynthetic rate (Pn), photochemical quantum yield (Fv/Fm), chlorophyll content, leaf water-holding capacity under drought condition compared with the hormone-free. The Pn of NE19, R270 and 107 was increased by 19%, 60% and 85%, respectively in BR treatment, and 35%, 50% and 80%, respectively in IAA treatment. The Fv/Fm of BR group increased by 7.7%, 7.5% and 10.9% compared with the non-hormone group, while the IAA group increased by 7.4%, 8% and 11.9%, respectively. The results indicated that exogenous BR and IAA improved the drought tolerance of Populus deltoides × P. nigra clones. Examining the leaf discs treated with exogenous hormones treatment and it was indicated that, for all three clones, the stomatal indix decreased by 12.28%, 25.60% and 20.31%, respectively in BR treatment, and the IAA treatment decreased by 13.00%, 13.15% and 14.48%, respectively. BR and IAA treatments inhibit stomatal development to reduce water loss under drought conditions.The expressions of EPF1, EPF2, EPFL9, ERECTA, FAMA, SDD1 in stomatal growth-related genes were detected by fluorescence quantitative PCR. EPF1, EPF2, ERECTA and SDD1 which negatively control stomatal development were increased, but the expressions of FAMA and EPFL9 which positively regulate the process were decreased. In summary, phytohormone BR and IAA are involved in the process of stomatal development in Populus deltoides × P.nigra, and increase drought resistance of poplar by inhibiting stomatal development under drought conditions.

       

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