Pedrosa A M, Cidade L C, Martins C P S, Macedo A F, Neves D M, Gomes F P, Floh E I S, Costa M G C
Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
Laboratório de Biologia Celular de Plantas, Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil.
Genet Mol Res. 2017 Mar 30;16(1):gmr-16-01-gmr.16019292. doi: 10.4238/gmr16019292.
9-cis-epoxycarotenoid dioxygenase (NCED) encodes a key enzyme in abscisic acid (ABA) biosynthesis. Little is known regarding the regulation of stress response by NCEDs at physiological levels. In the present study, we generated transgenic tobacco overexpressing an NCED3 ortholog from citrus (CsNCED3) and investigated its relevance in the regulation of drought stress tolerance. Wild-type (WT) and transgenic plants were grown under greenhouse conditions and subjected to drought stress for 10 days. Leaf predawn water potential (Ψw), stomatal conductance (gs), net photosynthetic rate (A), transpiration rate (E), instantaneous (A/E) and intrinsic (A/gs) water use efficiency (WUE), and in situ hydrogen peroxide (HO) and abscisic acid (ABA) production were determined in leaves of irrigated and drought-stressed plants. The Ψw decreased throughout the drought stress period in both WT and transgenic plants, but was restored after re-watering. No significant differences were observed in gs between WT and transgenic plants under normal conditions. However, the transgenic plants showed a decreased (P ≤ 0.01) gs on the 4th day of drought stress, which remained lower (P ≤ 0.001) than the WT until the end of the drought stress. The A and E levels in the transgenic plants were similar to those in WT; therefore, they exhibited increased A/gs under drought conditions. No significant differences in A, E, and gs values were observed between the WT and transgenic plants after re-watering. The transgenic plants had lower HO and higher ABA than the WT under drought conditions. Our results support the involvement of CsNCED3 in drought avoidance.
9-顺式环氧类胡萝卜素双加氧酶（NCED）编码脱落酸（ABA）生物合成中的一种关键酶。关于NCEDs在生理水平上对胁迫反应的调控知之甚少。在本研究中，我们培育了过表达柑橘NCED3直系同源基因（CsNCED3）的转基因烟草，并研究了其在干旱胁迫耐受性调控中的相关性。野生型（WT）和转基因植株在温室条件下生长，并进行10天的干旱胁迫处理。测定了灌溉和干旱胁迫植株叶片的黎明前水势（Ψw）、气孔导度（gs）、净光合速率（A）、蒸腾速率（E）、瞬时（A/E）和内在（A/gs）水分利用效率（WUE），以及原位过氧化氢（HO）和脱落酸（ABA）的产生量。在干旱胁迫期间，WT和转基因植株的Ψw均下降，但复水后恢复。在正常条件下，WT和转基因植株的gs未观察到显著差异。然而，在干旱胁迫第4天，转基因植株的gs下降（P≤0.01），直到干旱胁迫结束时仍低于WT（P≤0.001）。转基因植株的A和E水平与WT相似；因此，它们在干旱条件下表现出A/gs增加。复水后，WT和转基因植株的A、E和gs值未观察到显著差异。在干旱条件下，转基因植株的HO含量低于WT，而ABA含量高于WT。我们的结果支持CsNCED3参与干旱逃避。
