The Ethylene Synthesis Gene and Ethylene Receptor Gene Affect GA-DELLA and Jasmonic Acid Signaling in Regulating Flowering Time, Anther Dehiscence, and Flower Senescence in

In plants, the key enzyme in ethylene biosynthesis is 1-aminocyclopropane-1 carboxylic acid (ACC) synthase (ACS), which catalyzes -adenosyl-L-methionine (SAM) to ACC, the precursor of ethylene. Ethylene binds to its receptors, such as ethylene response 1 (ETR1), to switch on ethylene signal transduction. To understand the function of and in orchids, () and () from Gower Ramsey were functionally analyzed in . 35S:: caused late flowering and anther indehiscence phenotypes due to its effect on GA-DELLA signaling pathways. 35S:: repressed GA biosynthesis genes (, , and ), which caused the upregulation of DELLA [ (), (), and ] expression. The increase in DELLAs not only suppressed () expression and caused late flowering but also repressed the jasmonic acid (JA) biosynthesis gene and caused anther indehiscence by downregulating the endothecium-thickening-related genes , , and . The ectopic expression of an dominant-negative mutation () caused both ethylene and JA insensitivity in . 35S:: delayed flower/leaf senescence by suppressing downstream genes in ethylene signaling, including and , and in JA signaling, including and . JA signaling repression also resulted in indehiscent anthers the downregulation of , , , and . These results not only provide new insight into the functions of and orthologs but also uncover their functional interactions with other hormone signaling pathways, such as GA-DELLA and JA, in plants.