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. The Specifice objectives for the SCA include:. 1)Evaluating the post-production quality in petunias genetically-engineered for delayed senescence and increased stress tolerance;. 2)Identifying gene expression changes in transgenic plants with increased post-production quality; and. 3)Evaluating production characteristics of genetically-engineered petunias.
1b.Approach (from AD-416)
RNAi and Virus Induced Gene Silencing (VIGS) 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.
We continue to characterize the expression of genes involved in flower senescence and drought-induced postproduction decline. A large part of this research has investigated nutrient remobilization as a driving force for petal senescence in flowers. Petals are fairly nutrient poor compared to leaves and in contrast to leaf senescence only the major macronutrients nitrogen and phosphorus were found to be remobilized from naturally (age-related) senescing petals. When flowers are pollinated additional macro and micronutrients were found to be remobilized from the petals. Ethylene signaling plays a regulatory role in phosphorus recycling during petal senescence, and we are currently investigating the role of ethylene in nutrient remobilization from leaves. The expression of a family of high affinity phosphate transporters and other transport proteins identified from our proteomic and genomic investigations are currently being evaluated during natural and stress-induced senescence in flowers and leaves.
This research relates to the ARS parent project Objective 1b: Evaluate plant nutritional requirements to optimize production, enhance quality, and add value to ornamental end-products.
Progress was monitored on this project via written reports, meetings, and phone calls.