An annexin protein LpANN5 enhances drought and salt stress tolerance in perennial ryegrass

Abstract

Drought and salinity are severe environmental conditions that restrict the growth and reduce the quality of perennial ryegrass. The annexin family, as Ca2+- permeable transporters, is essential for plant stress responses and tolerance. This study identified an annexin gene, LpANN5, in perennial ryegrass. Subcellular localization observation suggested that LpANN5 protein was localized in the plasma membrane and cytoplasm. qRT-PCR revealed that the transcription of LpANN5 was upregulated by drought and salt treatments. LpANN5 overexpression in Arabidopsis and perennial ryegrass significantly enhanced plant drought and salt tolerance, while LpANN5 knock down resulted in a phenotype sensitive to drought and salt stress. In addition, stomatal aperture assay demonstrated that LpANN5 promoted stomatal closure under drought stress, and the detached leaf water loss rates were significantly decreased in LpANN5 overexpression plants but increased in LpANN5-RNA interference mutants. Furthermore, we demonstrated that LpANN5 mediates intracellular Ca2+-permeable transport in plant cells, and calcium channel inhibitors can impair the stress resistance regulation function of LpANN5. Thus, by modulating calcium signaling, LpANN5 is a positive regulator of drought and salt tolerance in perennial ryegrass.