Isolation and characterization of an aspartic proteinase gene from cowpea ( Vigna unguiculata L. Walp.)

A cowpea ( Vigna unguiculata cv. EPACE-1) aspartic proteinase (AP) gene was isolated by genomic library screening. Sequence analysis shows that this AP gene follows the same pattern of intron/exon number and organization as the other isolated plant AP genes, which are distinct from other solved AP genes. Northern blot analysis revealed that cowpea AP accumulates in leaves and stems but not in roots, indicating tissue-specific expression. An increased accumulation of transcripts during senescence suggests enzyme involvement in this process.