Cloning and expression analysis of voltage dependent anion channel (<italic>AhVDAC</italic>) gene in the geotropism response of the peanut gynophores

Abstract

<p id="C3">Peanut is a plant that blooms above ground and bears fruit underground. In our earlier studies, the voltage dependent anion channel (<italic>AhVDAC</italic>) gene was detected to be involved in gravitropism of peanut gynophores. In this study, the full-length cDNA of peanut <italic>AhVDAC</italic> gene was cloned, and the prokaryotic expression, subcellular localization, and the relative expression level of <italic>AhVDAC</italic> gene in gravitropism were analyzed. The results showed that the open reading frame of <italic>AhVDAC</italic> gene was 831 bp encoding a protein containing 276 amino acids, with a molecular weight of 29.7 kD and pI 6.38. Subcellular localization showed that <italic>AhVDAC</italic> gene was mainly located in cytoplasm. The prokaryotic expression vector pPROEXHTa-<italic>AhVDAC</italic> was constructed, and the 37 kD AhVDAC protein was induced, isolated, and purified. The relative expression level of <italic>AhVDAC</italic> in gynophores at different developmental days was analyzed by RT-PCR, and the results showed that the relative expression level of <italic>AhVDAC</italic> gene was the highest at the 2nd day, and then decreased gradually and maintained at a lower level. The application of exogenous CaCl₂ and LaCl₃ to peanut gynophores <italic>in vitro</italic> revealed that CaCl₂treatment could significantly promote the relative expression of <italic>AhVDAC</italic> gene and the geotropic bending of gynophores, whereas LaCl₃ treatment could decelerate the relative expression of <italic>AhVDAC</italic> gene and geotropic bending of gynophores. In conclusion, we speculated that Ca²⁺ accumulation may promote the expression of<italic> AhVDAC</italic> and Ca²⁺was asymmetrically distributed through the transport of AhVDAC on biological membrane, so that the growth direction of peanut gynophore was changed and geotropic bending occurs.