Journal Article

Negative reciprocal interactions between gibberellin and cytokinin in tomato

Weiss, David, Ori, Naomi, Fleishon, Shay, Shani, Eilon

2011

Overview

The hormones gibberellin (GA) and cytokinin (CK) exhibit antagonistic effects on various processes in many species. Previous studies in Arabidopsis have shown that GA inhibits CK signaling. Here, we have investigated the cross-talk between GA and CK in tomato (Solanum lycopersicum). We altered the balance between GA and CK activities by exogenous applications and genetic manipulations, and tested an array of physiological and developmental responses. GA and CK showed antagonistic effects on various developmental and molecular processes during tomato plant growth. GA inhibited all tested CK responses, including the induction of the CK primary response genes, type A Tomato Response Regulators (TRRs). CK also inhibited a subset of GA responses. In contrast with exogenous application of GA, the endogenous GA-independent GA signal generated by the loss of the DELLA gene PROCERA (PRO) did not repress CK-regulated processes, such as anthocyanin accumulation, TRR expression and leaf complexity. Our results suggest a mutual antagonistic interaction between GA and CK in tomato. Although GA may inhibit early steps in the CK response pathway via a DELLA-independent pathway, CK appears to affect downstream branch(es) of the GA signaling pathway. The ratio between the two hormones, rather than their absolute levels, determines the final response.

• Publisher: John Wiley & Sons,Blackwell Publishing Ltd,Wiley Subscription Services, Inc
• Subject: anatomy & histology / Anthocyanins / Anthocyanins - metabolism / Arabidopsis / cytokinin / Cytokinins / Cytokinins - metabolism / Cytokinins - pharmacology / drug effects / Gene expression regulation / Gene Expression Regulation, Plant / Gene Expression Regulation, Plant - drug effects / Genes / genetic engineering / genetics / gibberellin / Gibberellins / Gibberellins - metabolism / Gibberellins - pharmacology / growth & development / hormone interaction / Hormones / Hypocotyl / Hypocotyl - drug effects / Hypocotyl - growth & development / Hypocotyl - metabolism / leaf development / Leaves / Lycopersicon esculentum - drug effects / Lycopersicon esculentum - genetics / Lycopersicon esculentum - metabolism / metabolism / Mutation / Mutation - genetics / pharmacology / Physiological effects / physiological response / Plant growth / Plant growth substances / Plant interaction / Plant Leaves / Plant Leaves - anatomy & histology / Plant Leaves - drug effects / Plant Leaves - metabolism / Plant Proteins / Plant Proteins - genetics / Plant Proteins - metabolism / Plants / PROCERA / Regulator genes / Regulators / RNA, Messenger / RNA, Messenger - genetics / RNA, Messenger - metabolism / Seedlings / Seedlings - drug effects / Seedlings - metabolism / Signal transduction / Signaling / Solanum lycopersicum / tomato (Solanum lycopersicum) / Tomatoes