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.

中文翻译：

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酸转化酶通过维持小穗的能量同质化赋予水稻植物耐热性。

热应力会削弱花粉的萌发和花粉管的伸长，从而导致由能量不平衡引起的授粉失败。转化酶在维持能量稳态中起着至关重要的作用。然而，很少有研究在热应激期间对此进行研究。两种具有不同耐热性的水稻品种，即TLY83（耐热）和LLY722（热敏）受到热胁迫。在花期，热应激显着降低了小穗的繁殖力，并伴随着柱头上的花粉萌发显着减少和胚珠中的花粉管伸长，特别是在LLY722中。酸性转化酶（INV）而不是蔗糖合酶促进了蔗糖的代谢，这解释了两个品种的不同耐受性。在热胁迫下，NAD（H），ATP，与LLY722相比，TLY83具有抗氧化和抗氧化能力，而前者与后者相比，聚（ADP-核糖）聚合酶（PARP）活性急剧下降。重要的是，外源INV，3-氨基苯甲酰胺（一种PARP抑制剂），蔗糖，葡萄糖和果糖显着增加了热应激下的小穗繁殖力，其中INV活性增强而PARP活性受到抑制。因此，INV可以平衡能量的产生和消耗，以提供足够的能量用于花粉发芽和花粉管在热胁迫下的生长。果糖显着提高了热胁迫下的小穗繁殖力，其中INV活性增强而PARP活性受到抑制。因此，INV可以平衡能量的产生和消耗，以提供足够的能量用于花粉发芽和花粉管在热胁迫下的生长。果糖显着提高了热胁迫下的小穗繁殖力，其中INV活性增强而PARP活性受到抑制。因此，INV可以平衡能量的产生和消耗，以提供足够的能量用于花粉发芽和花粉管在热胁迫下的生长。