Prasad P V Vara, Djanaguiraman Maduraimuthu
Department of Agronomy, 2004 Throckmorton Plant Science Center, Kansas State University, Manhattan, KS 66506, USA.
Funct Plant Biol. 2011 Dec;38(12):993-1003. doi: 10.1071/FP11035.
High temperature stress is an important abiotic stress limiting sorghum (Sorghum bicolor (L.) Moench) yield in arid and semiarid regions. Climate models project greater increases in the magnitude of night temperature compared with day temperature. We hypothesise that high night temperature (HNT) during flowering will cause oxidative damage in leaves and pollen grains, leading to decreased photosynthesis and seed-set, respectively. The objectives of this research were to determine effects of HNT on (1) photochemical efficiency and photosynthesis of leaves, and (2) pollen functions and seed-set. Sorghum plants (hybrid DK-28E) were exposed to optimum night temperature (ONT; 32:22°C, day maximum: night minimum) or HNT (32:28°C, day maximum:night minimum) for 10 days after complete panicle emergence. Exposure to HNT increased thylakoid membrane damage and non-photochemical quenching. However, HNT decreased chlorophyll content, quantum yield of PSII, photochemical quenching, electron transport rate and photosynthesis of leaves as compared with ONT. Exposure to HNT increased the reactive oxygen species (ROS) level of leaves and pollen grains. Lipid molecular species analyses in pollen grains showed that HNT decreased phospholipid saturation levels and altered various phospholipid levels compared with ONT. These changes in phospholipids and greater ROS in pollen grains may be responsible for decreased pollen function, leading to lower seed-set.
高温胁迫是限制干旱和半干旱地区高粱（Sorghum bicolor (L.) Moench）产量的重要非生物胁迫因素。气候模型预测，夜间温度的升高幅度将大于白天温度。我们假设开花期的高夜温（HNT）会导致叶片和花粉粒的氧化损伤，分别导致光合作用和结实率下降。本研究的目的是确定高夜温对（1）叶片的光化学效率和光合作用，以及（2）花粉功能和结实率的影响。在高粱植株（杂交种DK-28E）完全抽穗后，将其置于最适夜温（ONT；32:22°C，日最高温度：夜最低温度）或高夜温（32:28°C，日最高温度：夜最低温度）下处理10天。暴露于高夜温会增加类囊体膜损伤和非光化学猝灭。然而，与最适夜温相比，高夜温会降低叶片的叶绿素含量、PSII的量子产率、光化学猝灭、电子传递速率和光合作用。暴露于高夜温会增加叶片和花粉粒中的活性氧（ROS）水平。花粉粒中的脂质分子种类分析表明，与最适夜温相比，高夜温会降低磷脂饱和度水平，并改变各种磷脂水平。花粉粒中磷脂的这些变化和更高的活性氧水平可能是花粉功能下降的原因，导致结实率降低。
