Abstract
Late embryogenesis abundant (LEA) proteins are known to accumulate in the late stage of seed development and in
vegetative tissues following environmental stress. They exist not only in plants but also some animals, fungi, and bacteria. LEA proteins have diverse structures and gene expression patterns and are considered to safeguard living cells against disadvantageous changes in environmental conditions. In this study, cDNAs encoding two LEA proteins, PnLEA1 and PnLEA2, were isolated and analyzed to characterize LEA proteins in black poplar (Populus nigra L.). The predicted PnLEA1 and PnLEA2 proteins were structurally different; namely, PnLEA1 was identified as an LEA_1 family protein with one LEA_1 domain, and PnLEA2 was identified as an LEA_2 family protein with two LEA_2 domains. The PnLEA1 and PnLEA2 genes were expressed in the roots and leaves. The expression of PnLEA1 was up-regulated by drought, salinity, and cold stress. The expression of PnLEA2 was also increased by drought and salinity stress, though the increment was smaller than PnLEA1. Both PnLEA1 and PnLEA2 conferred early tolerance to high salinity on the Escherichia coli that overexpressed them. These results suggest that PnLEA1 and PnLEA2 are involved in the mechanisms of tolerance to environmental stress in P. nigra.
