A new Em-like protein from Lactuca sativa, LsEm1, enhances drought and salt stress tolerance in Escherichia coli and rice

Abstract

Late embryogenesis abundant (LEA) proteins are closely related to abiotic stress tolerance of plants. In the present study, we identified a novel Em-like gene from lettuce, termed LsEm1, which could be classified into group 1 LEA proteins, and shared high homology with Cynara cardunculus Em protein. The LsEm1 protein contained three different 20-mer conserved elements (C-element, N-element, and M-element) in the C-termini, N-termini, and middle-region, respectively. The LsEm1 mRNAs were accumulated in all examined tissues during the flowering and mature stages, with a little accumulation in the roots and leaves during the seedling stage. Furthermore, the LsEm1 gene was also expressed in response to salt, dehydration, abscisic acid (ABA), and cold stresses in young seedlings. The LsEm1 protein could effectively reduce damage to the lactate dehydrogenase (LDH) and protect LDH activity under desiccation and salt treatments. The Escherichia coli cells overexpressing the LsEm1 gene showed a growth advantage over the control under drought and salt stresses. Moreover, LsEm1-overexpressing rice seeds were relatively sensitive to exogenously applied ABA, suggesting that the LsEm1 gene might depend on an ABA signaling pathway in response to environmental stresses. The transgenic rice plants overexpressing the LsEm1 gene showed higher tolerance to drought and salt stresses than did wild-type (WT) plants on the basis of the germination performances, higher survival rates, higher chlorophyll content, more accumulation of soluble sugar, lower relative electrolyte leakage, and higher superoxide dismutase activity under stress conditions. The LsEm1-overexpressing rice lines also showed less yield loss compared with WT rice under stress conditions. Furthermore, the LsEm1 gene had a positive effect on the expression of the OsCDPK9, OsCDPK13, OsCDPK15, OsCDPK25, and rab21 (rab16a) genes in transgenic rice under drought and salt stress conditions, implying that overexpression of these genes may be involved in the enhanced drought and salt tolerance of transgenic rice. Thus, this work paves the way for improvement in tolerance of crops by genetic engineering breeding.

Genome-wide characterization of BnaLEA gene family reveals a positive role of BnaLEA39 in freezing tolerance in rapeseed (Brassica napus L.)

“…Most of the BnaLEA genes (78/148) were highly expressed in mature seeds and lowly expressed in other tested tissues (Fig. 2), which is consistent with the characterization of LEA genes that accumulate in large amounts during the late stage of seed development [40]. Unexpectedly, most of the LEA_2, LEA_3 and DHN subgroup members, as well as BnaLEA39 and BnaLEA40 from LEA_6, were highly expressed across different vegetative and reproductive organs during different development stages (Fig.…”

“…Correspondingly, the promoter sequences of LEA_6 members were rich in light-responsive and defense hormone-responsive cis-regulatory elements, and LEA_6 members were induced by abiotic stress and hormones-treatments (Table S2 and Figure S3). Typical LEA genes were exhibited high expression levels in the late stages of seed development in Arabidopsis [44] and rice [40], Similarly, we found that most of the BnaLEA gene family members are also highly expressed in the late stage of seed development (Table S3 and Fig. 2).…”

“…It is imperative to explore genes that enhance the low-temperature tolerance in rapeseed. Numerous studies have shown the positive impact of LEA gene expression on stress tolerance in several crops, such as rice [40], maize [41], wheat [42], and rapeseed [43]. Nevertheless, there is a scarcity of reports speci cally focusing on the role of LEA genes in conferring freezing tolerance in rapeseed.…”

Combined Proteomic and Metabolomic Analysis of the Molecular Mechanism Underlying the Response to Salt Stress during Seed Germination in Barley

“…It is worth mentioning that LEA protein (HORVU1Hr1G059900.1, HOR-VU3Hr1G030650.1) was also identified in GN18, but the upregulated expression fold change was less than that of GN2 ( Table S2 ). Early methionine (Em) protein, characterized as group 1 LEA protein, was first identified and described in wheat embryos and is reported to play a fundamental role in the response to environmental stress [ 64 , 65 ]. Em protein CS41, which is significantly expressed in barley seeds after 24 h and 48 h of salt stress, can respond to ABA [ 66 ].…”

Analysis of LEA protein family members in Lepidium apetalum seeds and the expression of LaLEA1 in seedlings in response to abiotic stresses

“…In addition to low-temperature damage, the plants also experience drought and salt stress during seed germination and seedling growth. Considering the harsh growth environment of L. apetalum, late embryogenesis abundant (LEA) proteins have recently been investigated; LEA family proteins play an important role in abiotic stress tolerance in plants, including cold, drought, and salt stresses (Xiang et al 2018).…”