Expression And Functional Analysis Of Grape Aldehyde Dehydrogenase Gene ALDH2B8

Grapevine （Vitis vinifera） is an important perennial fruit crop worldwide. Actually, globalscarcity of water resources is increasing in addition to environmental pollution, desertification,soils and water salinity. These changes strengthen environmental stresses to which plants aresubjected every day and will become soon more severe with desertification that is coveringmore and more the world’s terrestrial area. Abiotic stressors are the primary cause of qualitylosses, reducing yields for grapevine and most major crop plants. When exposed to abioticstresses, plant would accumulate excessive amuounts of aldehydes, which are toxic becauseof their chemical reactivity. Thus, levels of aldehydes in cells must be well balanced.Aldehyde dehydrogenases （ALDHs） belong to a family of NAD（P）+-dependent enzymes thatcatalyze the oxidation of various toxic aldehydes to carboxylic acids. They have been reportedto play important roles in plant responses to various stresses. But only one grape aldehydedehydrogenase gene VqALDH2B4was reported. In this research, grape ALDH2B8gene wasisolated from grapevine, which is rapidly induced in response to NaCl treatment. Theexpression and function of ALDH2B8gene were studied. The main results were as follow:1. Results of real-time PCR showed that expression of ALDH2B8gene was induced bysalinity treatments in V. labrusca×V.vinifera cv. Kyoho seedlings. The expression level ofgrapevine ALDH2B8was highly induced by salt stress at3-12h treatment, and then decreasedto original level at24-48h. Furthermore, real-time PCR were performed to investigateexpression profiles of the grapevine ALDH2B8gene in different organs. Grapevine ALDH2B8showed distinct expression patterns in root, stem, leave, flower, fruit and tendril of V. labrusca×V.vinifera cv. Kyoho seedlings, with the highest expression in flowers, and lowest in fruits.2. In the present study, a1617bp fragment containing a complete open reading frame（ORF） of ALDH2B8was cloned from V. labrusca×V.vinifera cv. Kyoho. Sequence analysisindicated that the grapevine ALDH2B8encodes a protein of538amino acids. The codingsequences of the ALDH2B8in V. vinifera and Kyoho shared99.63%identity with thatidentified from the V. Vinifera and their protein sequences are identical. Alignment of thededuced amino acid sequences showed that the grapevine ALDH2B8shared79.11%,75.89%,71.61%,53.21%identity, respectively, with the homologs from V.pseudoreticulata （GenBankaccession no. DQ150256）, Zea mays （GenBank accession no. NP₀01105891）, Oryza sativa （GenBank accession no. NP₀01048010） and Homo sapiens （GenBank accession no.AAT41621）.3. Transient expression grapevine ALDH2B8-GFP fusion protein in Arabidopsis thalianaprotoplasts by PEG showed that grapevine ALDH2B8was localized in mitochondrial.4. Over-expression of grapevine ALDH2B8sustains Arabidopsis growth upon salt stressand protects plants against oxidative stress, which is accompanied by less MDA and ROSaccumulation.