Exogenously-supplied trehalose inhibits the growth of wheat seedlings under high temperature by affecting plant hormone levels and cell cycle processes.

High temperature reduces the yield of crops, and exogenous trehalose can improve the stress resistance of plants. However, the mechanism by which trehalose causes phenotypic changes in plants is still unknown. Here we investigated the effects of exogenously supplied trehalose (1.5 mM) during high-temperature stress and subsequent recovery on plant hormones and cell cycle in wheat seedlings. Our results showed that after high-temperature stress, exogenously supplied trehalose reduced the root length, vertical height, leaf area, and leaf length of wheat seedlings, thereby reducing their growth. However, the content of hormones, such as abscisic acid, auxin (IAA), gibberellin (GA3), and cytokinin in seedlings pretreated with trehalose and high-temperature stress was lower than that under high-temperature stress alone. Our further experiments showed that the levels of these hormones were affected by genes involved in hormone biosynthesis and decomposition pathways in trehalose-pretreated seedlings. Compared with control plants, the activity of IAA oxidase is also higher. In addition, exogenous trehalose decreased the transcriptional levels of CycD2 and CDC2 (two genes regulating cell cycle progression) under heat stress, and reduced the activity of vacuolar invertase after recovery from heat stress, thereby shortening the cell length. These results indicate that trehalose inhibits wheat growth at high temperature by affecting plant hormone levels and the cell cycle process.AbbreviationsABA, abscisic acid; CDK, cyclin-dependent kinase; CycD, D-type cyclins; GA3, gibberellin; IAA, auxin; KRP, KIP-related protein; T6P, trehalsoe-6-phosphate; VIN, vacuolar invertase.