National Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China.
Plant Cell Environ. 2020 May;43(5):1273-1287. doi: 10.1111/pce.13733. Epub 2020 Feb 17.
Heat stress impairs both pollen germination and pollen tube elongation, resulting in pollination failure caused by energy imbalance. Invertase plays a critical role in the maintenance of energy homoeostasis; however, few studies investigated this during heat stress. Two rice cultivars with different heat tolerance, namely, TLY83 (heat tolerant) and LLY722 (heat susceptible), were subjected to heat stress. At anthesis, heat stress significantly decreased spikelet fertility, accompanied by notable reductions in pollen germination on stigma and pollen tube elongation in ovule, especially in LLY722. Acid invertase (INV), rather than sucrose synthase, contributed to sucrose metabolism, which explains the different tolerances of both cultivars. Under heat stress, larger enhancements in NAD(H), ATP, and antioxidant capacity were found in TLY83 compared with LLY722, whereas a sharp reduction in poly(ADP-ribose) polymerase (PARP) activity was found in the former compared with the latter. Importantly, exogenous INV, 3-aminobenzamide (a PARP inhibitor), sucrose, glucose, and fructose significantly increased spikelet fertility under heat stress, where INV activity was enhanced and PARP activity was inhibited. Therefore, INV can balance the energy production and consumption to provide sufficient energy for pollen germination and pollen tube growth under heat stress.
热应激会损害花粉的萌发和花粉管的伸长，导致授粉失败，造成能量失衡。转化酶在维持能量平衡方面起着关键作用；然而，很少有研究在热应激期间对此进行研究。选用两个具有不同耐热性的水稻品种，即 TLY83（耐热）和 LLY722（热敏），进行热胁迫处理。在开花期，热胁迫显著降低了小穗育性，同时花粉在柱头的萌发和花粉管在胚珠中的伸长明显减少，在 LLY722 中尤为明显。酸性转化酶（INV）而非蔗糖合酶参与蔗糖代谢，这解释了两个品种的不同耐热性。在热胁迫下，TLY83 中 NAD（H）、ATP 和抗氧化能力的增强幅度明显大于 LLY722，而前者中聚（ADP-核糖）聚合酶（PARP）活性的急剧下降则大于后者。重要的是，外源 INV、3-氨基苯甲酰胺（PARP 抑制剂）、蔗糖、葡萄糖和果糖在热胁迫下显著提高了小穗育性，其中 INV 活性增强，PARP 活性受到抑制。因此，INV 可以平衡能量的产生和消耗，为花粉萌发和花粉管生长提供足够的能量。
