Cloning and Expression Analysis of Fusarium Wilt Resistance-Related Gene <I>PvCaM1</I> in Common Bean (<I>Phaseolus vulgaris</I> L.)

Abstract

Calmodulin (CaM) is a multifunctional Ca 2+ -binding protein in plant cells. It plays important roles in regulating the growth, development and disease resistance in plants. A full-length cDNA sequence coding for CaM in common bean was cloned based on expressed sequence tags from common bean. Sequence analysis showed that the isolated fragment was 713 bp, it contained an open reading frame (ORF) of 453 bp encoding 150 amino acids with a theoretical molecular weight of 17.16 kD, designated PvCaM1 (GenBank accession number JN418801),. Online ScanProsite tool analysis showed that PvCaM1 had four Ca 2+ -binding domains with the function of combining with free Ca 2+ . Homology analysis indicated that PvCaM1 gene was similar to CaM genes in other plant species including Lotus japonicus (CAB63264.3), watermelon (BAI52955.1), Populus (ADC80735.1) and castor bean (XP_002533357.1)．Phylogenetic analysis based on the amino acids sequence of PvCaM1 with other nine species showed that the protein encoded by this gene had the closest relationship with the CaM in Lotus japonicus and watermelon, the homology were 77% and 76%, respectively. Real time-PCR analysis indicated that the expression level of PvCaM1 in the interactions between the resistant cultivars and Fusarium wilt pathogen FOP-DM01 ( Fusarium oxysporum f. sp. phaseoli ) increased significantly and reached the peak at 96 h, however, the susceptible one touched the bottom under the same conditions．The expression level of PvCaM1 in 260205 leaves was higher than that in BRB-130 at all different time points. PvCaM1 expressed differently in the leaves, stems and roots, the expression level in leaves was higher than that in roots and stems. Transcriptional level of PvCaM1 was up-regulated by exogenous abscisic acid, methyl jasmonate and ethephon, but not increased significantly by salicylic acid and 3-indoleacetic acid. These results suggested that PvCaM1 is probably involved in the abscisic acid, jasmonic acid and ethylene-regulated resistant response pathways, but not closely related to the salicylic acid and 3-indoleacetic acid pathway. The study indicated that the function of PvCaM1 should be closely related to the resistant response pathways against Fusarium wilt pathogen FOP-DM01 with involvement of abscisic acid, jasmonic acid and ethylene in common bean.