Abstract

Effects of drought stress on photosynthesis have been well-documented. However, photosynthetic electron transport process in response to combined drought stress and recovery in maize is relatively scant. In this study, the photosynthetic electron flow, the energy quenching in PSII and PSI, and cyclic electron flow (CEF) activity in two maize (Zea mays L.) genotypes were measured. In both genotypes, chlorophyll a fluorescence transient (OJIP) showed progressive drought caused increases of J and I step, the positive of K-band and L-band; and decreases in TR₀/ABS, ET₀/TR₀, ET₀/ABS, RE₀/ET₀ and PI_ABS. Analysis of the modulated 820 nm reflection (MR) showed progressive drought decreased the values of V_PSI and V_PSII-PSI. Decreases in quantum yields of Y(I) and Y(II) were accompanied by increase of Y(NPQ) and CEF. Compare to Shaanke9 (SK9), the drought-induced changes in Dafeng30 (DF30) were stronger, and SK9 kept higher CEF under drought stress. After re-watering, SK9 recovered more completely in all parameters than DF30, suggesting that the reversible down-regulation of PSII and PSI in SK9 maintained the functional integrity of photosystems. The photosynthetic apparatus of SK9 cultivar is more resistant to drought than that of DF30. These results indicate that more efficient regulation of photosynthetic electron transport between two photosystems and higher CEF in the SK9 jointly play crucial role in recovery from drought damages, which could contribute to a better adaptation under varying drought environment.

中文翻译：

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两种玉米基因型光合电子输运对干旱和复水的响应

摘要

干旱胁迫对光合作用的影响已得到充分证明。但是，响应干旱胁迫和玉米恢复的光合电子传递过程相对较少。在这项研究中，在2个玉米光合电子流，在PSII和PSI能量淬火，和环状的电子流动（CEF）活性（玉蜀黍L.）的基因型进行测定。在两种基因型中，叶绿素a荧光瞬变（OJIP）均显示出进行性干旱导致J和I阶跃增加，K波段和L波段为阳性。并减少TR ₀ / ABS，ET ₀ / TR ₀，ET ₀ / ABS，RE ₀ / ET ₀和PI _ABS。对调制的820 nm反射（MR）的分析显示，进行性干旱降低了V _PSI和V _{PSII-PSI的值}。Y（I）和Y（II）量子产率的下降伴随着Y（NPQ）和CEF的增加。与Shaanke9（SK9）相比，干旱引起的Dafeng30（DF30）变化更强，而SK9在干旱胁迫下保持较高的CEF。再浇水后，SK9的所有参数均比DF30更完全地恢复，这表明SK9中PSII和PSI的可逆下调保持了光系统的功能完整性。与DF30相比，SK9品种的光合装置更耐干旱。这些结果表明，更有效地调节两个光系统之间的光合作用电子传递以及SK9中较高的CEF共同在从干旱损害中恢复中起关键作用，这可能有助于在变化的干旱环境下更好地适应气候变化。