Interaction of 4-chloroindole-3-acetic acid and gibberellins in early pea fruit development

In pea, normal pod (pericarp) growth requires the presence of seeds; and in the absence of seeds, gibberellins (GAs) and/or auxins can stimulate peric arp growth. To further characterize the function of naturally occurring pea GAs and the auxin, 4-chloroindole-3-acetic acid (4-Cl-IAA), on pea fruit d evelopment, profiles of the biological activities of GA(3), GA(1), and 4-Cl -IAA on pericarp growth were determined separately and in combination on po llinated deseeded ovaries (split-pericarp assay) and nonpollinated ovaries. Nonpollinated ovaries (pericarps) responded differently to exogenous GAs a nd 4-Cl-IAA than pollinated deseeded pericarps. In nonpollinated pericarps, both GA(3) and 4-Cl-IAA stimulated pericarp growth, but GA3 was significan tly more active in stimulating all measured parameters of pericarp growth t han 4-Cl-IAA. 4-Cl-IAA, GA(1), and GA(3) were observed to stimulate pericar p growth similarly in pollinated deseeded pericarps. In addition, the syner gistic effect of simultaneous application of 4-Cl-IAA and GAs on pollinated deseeded pericarp growth supports the hypothesis that GAs and 4-Cl-IAA are involved in the growth and development of pollinated ovaries.