Phosphoproteomic Profiling Deciphers Heat-Stress-Responsive Mechanisms in Passion Fruit
2025
Liang Li | Yajun Tang | Dong Yu | Ping Zhou | Zhicheng Liu | Xiuqing Wei | Jiahui Xu
Heat stress severely inhibited the flower bud growth and development of passion fruit (<i>Passiflora edulis</i> Sims) in summer, resulting in severe production damage. Protein phosphorylation plays a key role in plant protein regulatory networks in response to abiotic stress, while the mechanism of phosphorylation regulation response to heat stress in passion fruit is still unknown. In this study, 97.62% of passion fruit floral buds withered and fell off after 2 h of heat stress, compared to 3.33% after 0.5 h. A total of 10,614 phosphorylation sites across 2906 proteins were identified by phosphoproteomic analysis. Among them, 1343 differentially regulated phosphoproteins (DRPPs) were mainly located in the nucleus, cytoplasm, and chloroplast. The DRPPs whose phosphorylation sites were induced by heat stress were mainly involved in the ‘ABC transporters’, ‘Plant hormone signal transduction’, and ‘MAPK signaling’ pathways. In addition, the accumulations of ABA and H<sub>2</sub>O<sub>2</sub> were induced under heat stress for 0.5 h. Through protein interaction prediction and qRT-PCR analyses, we identified a key protein PePP2C1, in which the levels of gene expression, protein expression, and phosphorylation were induced by heat stress. The transient assays showed that the overexpression of <i>PePP2C1</i> inhibited the accumulation of H<sub>2</sub>O<sub>2</sub>. Our results suggested the potential role of phosphoproteins under heat stress in the floral buds of passion fruit. The findings in this study contribute to a better understanding of the molecular mechanism of phosphoproteins in response to heat stress.
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