Department of Agronomy, Throckmorton Plant Science Center, Kansas State University, Manhattan, KS, 66506, USA.
Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, TN, 641003, India.
Plant Cell Environ. 2018 May;41(5):1065-1082. doi: 10.1111/pce.13089. Epub 2017 Nov 2.
High temperature (HT) decreases seed set percentage in sorghum (Sorghum bicolor [L.] Moench). The relative sensitivity of pollen and particularly pistil and the mechanistic response that induces tolerance or susceptibility to HT are not well known and hence are the major objectives of this research. The male sterile (ATx399) and fertile (RTx430) lines were exposed to 30/20 °C (optimum temperature), 36/26 °C (HT ), and 39/29 °C (HT ) from the start of booting to seed set in a controlled environment. Similarly, in the field, HT stress was imposed using heat tents. HT stress decreased pollen germination. Relatively high levels of reactive oxygen species and decreased antioxidant enzyme activity and phospholipid unsaturation were observed in pollen compared to pistil under HT. The severe cell organelle damage was observed in pollen and pistil at 36/26 and 39/29 °C, respectively. The seed set percentage was higher in HT-stressed pistil pollinated with optimum-temperature pollen. Direct and reciprocal crosses indicate that pollen was more sensitive with larger decreases in seed set percentage than pistil under HT stress. The negative impact was greater in pollen than pistil at lower temperatures. Overall, pollen was more sensitive than pistil to HT stress because it is more susceptible to oxidative damage than pistil.
高温（HT）会降低高粱（Sorghum bicolor [L.] Moench）的结实率。花粉，特别是雌蕊对 HT 的相对敏感性以及导致对 HT 耐受或敏感的机制反应尚不清楚，因此这是本研究的主要目标。在受控环境中，从抽穗开始到种子形成，雄性不育（ATx399）和可育（RTx430）系分别暴露于 30/20°C（最适温度）、36/26°C（HT）和 39/29°C（HT）。同样，在田间，使用热帐篷施加 HT 应激。HT 应激会降低花粉的萌发率。与雌蕊相比，在 HT 下，花粉中观察到相对较高水平的活性氧、抗氧化酶活性降低和磷脂不饱和。在 36/26 和 39/29°C 时，分别在花粉和雌蕊中观察到严重的细胞器损伤。在 HT 胁迫下，用最适温度花粉授粉的雌蕊结实率较高。直接和回交表明，在 HT 胁迫下，花粉比雌蕊的结实率下降更大，敏感性更高。在较低温度下，对花粉的负面影响大于雌蕊。总的来说，花粉比雌蕊对 HT 胁迫更敏感，因为它比雌蕊更容易受到氧化损伤。
