2007 Annual Report 1a.Objectives (from AD-416) Ethylene gas and environmental stresses during shipping, in retail environments, and in the home and garden can accelerate leaf and flower senescence and reduce the quality and salability of ornamental plants. The objective of this cooperative research project is to create genetically engineered petunias with delayed senescence and stress tolerance and to evaluate production and post production characteristics of these plants. 1b.Approach (from AD-416) RNAi technologies will be used to knock down the expression of endogenous senescence-related genes in transgenic petunias. Post-production characteristics of transgenic plants will be evaluated following ethylene exposure, high temperature and water stress. Production characteristics including disease tolerance will be evaluated in greenhouse studies. Large scale changes in gene expression in selected transgenic plants will be identified using petunia oligo-based DNA microarrays. 3.Progress Report This report documents research conducted under a Specific Cooperative Agreement between ARS and The Ohio State University initiated in FY 2005. Virus induced gene silencing methods were used to knock out (i.e. down regulate) additional genes involved in flower senescence. Target genes will be those identified in microarray experiments. Two-dimensional protein gels were used to compare protein profiles in transformed and non transformed plants. These experiments will identify proteins that are modified by inhibiting the expression of individual senescence-related genes. DNA microarrays were be used to identify genes that are differentially expressed between transformed and non transformed plants. Expression analyses have identified genes that are transcriptionally up regulated during flower petal senescence in petunias. Expression of these genes during leaf senescence and following drought stress has been evaluated. Two target genes have been selected that appear to play a role in natural and stress-induced senescence. Two senescence-related genes have been silenced in transgenic (RNAi) petunias. The promoter from a senescence-specific gene (PhSAG10) has been cloned. Nutrient levels have been measured during flower development and senescence to identify the nutrients that are remobilized during the senescence and death of the petals. Genes involved in nutrient remobilization have been cloned and sequenced. 4.Accomplishments This is part of NP 305 "Integrated Production Systems, "Agroengineering, Agrochemical, and Related Technology", and NP 303 "Plant Diseases". Expression analyses have identified genes that are transcriptionally up regulated during flower petal senescence in petunias. Expression of these genes during leaf senescence and following drought stress has been evaluated. Two target genes have been selected that appear to play a role in natural and stress-induced senescence. The impact of this work will permit increased stress tolerance in petunias. Other significant accomplishments. Two senescence-related genes have been silenced in transgenic (RNAi) petunias. The promoter from a senescence-specific gene (PhSAG10) has been cloned. Nutrient levels have been measured during flower development and senescence to identify the nutrients that are remobilized during the senescence and death of the petals. Genes involved in nutrient remobilization have been cloned and sequenced. Production of stress tolerant plants will result. • Two-dimensional protein gels will be used to compare protein profiles in transformed and non transformed plants. These experiments will identify proteins that are modified by inhibiting the expression of individual senescence-related genes. DNA microarrays will be used to identify genes. • Virus induced gene silencing methods will be used to knock out (i.e. down regulate) additional genes involved in flower senescence. Target genes will be those identified in microarray experiments. Detection of stress will be enhanced. Expected benefits of the project are increased profitability for growers, enhanced plant quality and improved knowledge of soilless media production in the greenhouse. A Master Memorandum of Understanding with the University of Toledo; Specific Cooperative Agreements with the University of Toledo, North Carolina State University, University of Florida, and The Ohio State University, a Research Support Agreement with the University of Toledo, and the formalization of a Liaison Committee have been established. An extramural economic study, organized by the University of Toledo, was conducted to survey the regional greenhouse/floricultural industry which will provide baseline information to identify priority research needs for the project to address. The Toledo Botanical Garden and the Ohio State University Extension have expressed interest in assisting in technology transfer activities as research information is generated. Nutritional information on geraniums has been conducted and distributed to growers through a full color booklet and a hands on demonstration at the growers winter meeting. 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Number of web sites managed 1 Number of non-peer reviewed presentations and proceedings 2