Parthenocarpic tomato mutants, iaa9-3 and iaa9-5, show plant adaptability and fruiting ability under heat-stress conditions

Fruit set is one of the main problems that arise in tomato plants under heat-stress conditions, which disrupt pollen development, resulting in decreased pollen fertility. Parthenocarpic tomatoes can be used to increase plant productivity during failure of the fertilisation process under heat-stress conditions. The aim of this study were to identify the plant adaptability and fruiting capability of ?iaa9-3 and iaa9-5 tomato mutants under heat-stress conditions. The iaa9-3 and iaa9-5 and wild-type Micro-Tom (WT-MT) plants were cultivated under two temperature conditions: normal and heat-stress conditions during plant growth. The results showed that under the heat-stress condition, iaa9-3 and iaa9-5 showed delayed flowering time, increased number of flowers, and increased fruit set and produced normal-sized fruit. However, WT-MT cannot produce fruits under heat stress. The mutants can grow under heat-stress conditions, as indicated by the lower electrolyte leakage and H₂O₂ concentration and higher antioxidant activities compared with WT-MT under heat-stress conditions. These results suggest that iaa9-3 and iaa9-5 can be valuable genetic resources for the development of tomatoes in high-temperature environmental conditions.