Cloning and characterization of a cowpea seed lipid transfer protein cDNA: expression analysis during seed development and under fungal and cold stresses in seedlingsʹ tissues

Lipid transfer proteins (LTPs) are antimicrobial peptides (AMPs) involved in the defense of plants against pathogens. Our group has previously characterized and purified a LTP from cowpea (Vigna unguiculata (L.) Walp.) seeds which caused the inhibition of growth of fungal pathogens in vitro. The aim of this work was to obtain the cDNA encoding the cowpea LTP and after cloning, to use the cDNA as a probe for studying its expression profile during the development of cowpea seeds. In this work, the N-terminal sequence of the mature LTP peptide from cowpea was used to produce a degenerated oligonucleotide. This primer allowed the amplification of the LTP cDNA by RT-PCR from mRNA of cowpea seeds. The sequence analysis of the cloned cDNA, named VULTP, showed 494 bp which encoded a polypeptide of 91 amino acids. The deduced peptide presented high homology of similarity to plant LTPs of Vigna radiata var. radiate (94%), Prunus domestica (82%) and Zea mays (72%). The expression profile of the VULTP gene in cowpea was analyzed by Northern blot and revealed that the transcript is not accumulated in adult tissues. Conversely, VULTP mRNA is early and strongly accumulated during seed development. The results obtained to seedling of cowpea demonstrate that the VULTP gene presents differential expression in response to different stress. Further studies will be conducted to try to gain better understanding about the physiological role of this gene in cowpea.