Induction Kinetics of a Novel Stress-related LEA Gene in Wheat

Drought, high-salt, and low-temperature are major constraints to yield and quality of crops. Late embryogenesis abundant proteins (LEAs), characterized by high hydrophilic and thermal stabilities, stabilize the cell membrane structure and prevent oxidation. LEA genes mediate responses to abiotic stresses such as drought, salt, low-temperature, or ultraviolet radiation. In this study, TaLEA4, a Group III member from the LEA family, was cloned from a cDNA library of stress-treated wheat seedlings by in situ phage hybridization. The full length clone of TaLEA4 is 1,084 bp and contains a 570 bp open reading frame (ORF) encoding a 189-amino-acid protein. Multiple sequence alignment indicated that TaLEA4 had three incompletely repetitive 11-mer amino acid motifs and alpha-helix domains. The prediction of protein-sorting signals and localization sites in amino acid sequences (PSORT) showed that TaLEA4 has a nuclear localization signal (NLS) in the amino acid C-terminal sequence. A subcellular localization assay showed that the TaLEA4 protein accumulates in the cytoplasm and the nucleus. Specific expression in various wheat organs indicated that TaLEA4 mRNAs accumulates in abundance in stems under normal growing conditions. Expression profile analysis showed that TaLEA4 was highly induced by drought, and low and high temperatures. Isolation of the TaLEA4 promoter revealed a core promoter element and some cis-acting elements responding to abiotic stresses. This study provides a basis for more detailed functional analyses of LEA proteins, and suggests ways of improving wheat resistance by molecular breeding.