Poster: Hormone synthesis & metabolism

Abs # 483: A complex ACC synthase gene family regulates ethylene biosynthesis during soybean abscission

Presenter:	Meng, Xin , xinmeng@iastate.edu
Authors	Meng, Xin  (A)   Cai, Suqin  (A)   Lashbrook, Coralie C. (A)
Affiliations:	(A): Iowa State University Horticulture Department

Modulation of ethylene biosynthesis is a fundamental response of plants faced with fluctuations in their internal or external environments. Differential regulation of specific 1-aminocyclopropane-1-carboxylate synthase enzymes (ACC synthases) that catalyze the rate-limiting step of ethylene biosynthesis may coordinate developmental transitions within the plant life cycle and defensive or adaptive responses to environmental stress. Our research goal is to reveal the biosynthetic mechanisms that underlie ethylene’s control of organ abscission in soybean. Soybean was selected for study because its yield capacity is routinely lowered by high rates of reproductive organ abscission in response to abiotic stress. We have integrated molecular genetic and functional genomic approaches to reveal the presence of at least thirteen subclasses of ACC synthase genes expressed in soybean. Nucleotide sequence identity varies from approximately 77% to 98% among family members sequenced so far. Differential regulation of ethylene biosynthesis by distinct gene family members is observed in multiple soybean tissues including vegetative and reproductive abscission zones and flanking tissues during developmental and stress-mediated abscission.