Abstract
Late embryogenesis abundant (LEA) proteins are a diverse and large group of polypeptides that play important roles in desiccation and freezing tolerance in plants. The LEA family has been systematically characterized in some plants but not Brassica napus. In this study, 108 BnLEA genes were identified in the B. napus genome and classified into eight families based on their conserved domains. Protein sequence alignments revealed an abundance of alanine, lysine and glutamic acid residues in BnLEA proteins. The BnLEA gene structure has few introns (<3), and they are distributed unevenly across all 19 chromosomes in B. napus, occurring as gene clusters in chromosomes A9, C2, C4 and C5. More than two-thirds of the BnLEA genes are associated with segmental duplication. Synteny analysis revealed that most LEA genes are conserved, although gene losses or gains were also identified. These results suggest that segmental duplication and whole-genome duplication played a major role in the expansion of the BnLEA gene family. Expression profiles analysis indicated that expression of most BnLEAs was increased in leaves and late stage seeds. This study presents a comprehensive overview of the LEA gene family in B. napus and provides new insights into the formation of this family.
Highlights
Drought stress is an abiotic environmental state that can affect the morphological, physiological and biochemical characteristics of plants and lead to reductions in crop productivity due to adverse effects on plant growth[1]
The genome-wide identification of Late embryogenesis abundant (LEA) gene families in B. napus was based on homology with LEA genes from Arabidopsis identified using the CNS-Genoscope database
The present results indicated that the accumulation of BnLEA genes was associated with different tissues, and the expression pattern differed among each LEA gene family (Fig. 7)
Summary
Drought stress is an abiotic environmental state that can affect the morphological, physiological and biochemical characteristics of plants and lead to reductions in crop productivity due to adverse effects on plant growth[1]. LEA proteins aid the formation of the glassy state, in which nonreducing sugars accumulate in the cytoplasm of plants during periods of desiccation[16]. These finding imply that LEA proteins play a role in protecting plants from dehydration. The amino acid residue homology of Group 5 proteins is low, which implies that these proteins are probably involved in seed maturation and dehydration[21]. The Group 4 LEA protein of B. napus enhances abiotic stress tolerance in both Escherichia coli and transgenic Arabidopsis plants[22]. LEA proteins have been observed in B. napus lines with higher oil contents, suggesting that LEA proteins might contribute to dehydration tolerance during the oil-accumulation period and increased B. napus oil content[25]
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