Cross-talk between brassinosteroid and ethylene in sugarcane ripening: regulation of ACC synthase via brassinosteroid

• Grant number: 14/10003-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: December 01, 2014
• End date: January 31, 2019
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Marcelo Menossi Teixeira
• Grantee: José Sérgio de Macedo Soares
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 13/15576-5 - Molecular approaches to study the relationship between ethylene and sugarcane ripening, AP.BIOEN.TEM
• Associated scholarship(s): 15/25469-7 - Regulation of ACC synthase in response to brassinosteroid, BE.EP.PD

Abstract

Sugarcane is a C4 plant that has a unique capacity to accumulate high concentrations of sucrose in the stem. Ethylene is phytohormone that plays an important role on regulation of growth and sucrose accumulation of sugarcane. The rate limiting step of ethylene biosynthesis is mediated by the enzyme 1-aminocyclopropane-1-carboxylase synthase (ACS). In several hormone biosynthesis and signaling pathways, protein turnover has emerged as a common regulatory element. These proteins may function as cross-talk points, interconnecting hormone signaling pathway with molecular mechanisms regulating various aspects of plant physiology. Brassinosteroid (BR) is steroid hormone and function as a master regulator of plant growth and belong to a group of factors influencing ethylene biosynthesis through regulation of ACS protein stability. In this research project we will investigate the effects of brassinosteroid in ethylene biosynthesis via sugarcane ACS regulation. Initially, we will evaluate if BRs induce the ethylene biosynthesis in sugarcane seedlings. To expand the comprehension of the BR signaling components involved in ethylene biosynthesis we will measure ethylene emission in rice loss-of-function BR signaling mutants. To complement this assay we also expect to identify a physical interaction between sugarcane proteins homologous to BR signaling proteins (ScBRI1, ScBAK1 or ScBZR1) and three different sugarcane ACS isoforms via bimolecular fluorescence complementation using rice protoplasts. And to determine if ethylene production by BR is the result of an increase in ACSs stability in vivo we will measure the levels of fusion proteins in transgenic rice seedlings expressing sugarcane myc-epitope-tagged ACS under the control of the dexamethasone inducible promoter in the presence of BR. The elucidation of ACS regulation mechanism via brassinosteroid signaling will provide significant knowledge not only in sugarcane growth and ripening, but also for plant in general. (AU)