Interaction of calcium with indole-3-acetic acid and kinetin during the formation of local lesions in bean (Phaseolus vulgaris) by alfalfa mosaic virus

Abstract

A study was conducted on the interaction of Ca2+ with 3-indoleacetic acid (IAA) and kinetin on local lesion formation by alfalfa mosaic virus on bean leaves. Local lesion number was reduced when IAA solutions alone were applied as postinoculation sprays, as compared with water sprays. The reduction was slight at 10−4 and 10−5 M but was large at 10−3 M. Although addition of 0.03 M CaCl2 to 10−4 and 10−5 M IAA sprays reversed the effect of IAA on local lesion formation, addition of the same concentration of calcium to 10−3 M IAA had little effect on local lesion production. Kinetin, except at the 10−4 M concentration, caused no increase in the number of local lesions, as compared with treatment with distilled water. However, with 0.03 M CaCl2 added, the local lesion production at all kinetin concentrations increased significantly over distilled water or 0.03 M CaCl2. The sizes of local lesions on leaves sprayed with 10−3, 10−4, and 10−5 M IAA were reduced by approximately 52, 26, and 10%, respectively, and on leaves sprayed with kinetin by approximately 44, 26, and 24%, respectively. Addition of 0.03 M CaCl2 to IAA and kinetin lessened their effect on the size of local lesions but did not eliminate the effect totally.