Regulation of Ethylene Production During Postproduction Handling of Flower Crops Progress Report — september 1994
Date August 29, 1994
Title of Project Regulation of Ethylene Production during Postproduction Handling
of Flower Crops
Institution where work is being conducted Purdue University
Amount of Endowment Grant $ 10,000
Covering Period 1/1/94 to 12/31/94
Anticipated Date of Project Completion/Final Report 12/31/96
Individual(s) Conducting Project:
(List Project Leader First)
William R. Woodson - Title Professor
Telephone Number 317-494-1337
Regulation of Ethylene Production during Postproduction Handling of Flower Crops
William R. Woodson
Purdue University
- A. Project Objectives:
- The overall objective of this work is to understand the mechanism by which flowercrops regulate the production of ethylene during postproduction handling. The basic
question being addressed by our research is: Why do many flowers suddenly switch to a
situation of high ethylene production at certain developmental stages, following pollination,
or in response to postproduction handling practices? Our ultimate goal is to identify those
cellular factors that lead to the increased ethylene and subsequently design genetic control
measures to improve the postproduction quality of flower crops.
- B. Summary of Work to Date:
- In order to begin to address the regulation of ethylene production at the cellular level itwas necessary for us to identify the genes encoding enzymes responsible for the synthesis
of ethylene. These include ACC synthase and ACC oxidase, which convert s-adenosylmethionine
to ACC and ACC to ethylene, respectively. To date we have identified
several genes for both ACC synthase and ACC oxidase from carnation, snapdragon and
petunia. We have characterized these genes in detail and found them to be regulated in very
specific manners. For example, when carnations are pollinated one ACC synthase gene is
induced in the pistil that leads to increased ethylene production by this organ.
Subsequently, this increased ethylene triggers the petals to express another ACC synthase
leading to increased petal ethylene. Thus, pollination leads to a “wave’ of ethylene through
the flower ultimately leading the petals to senesce prematurely. We have also found that the
harvesting of carnation flowers leads to the induction of both ACC synthase and ACC
oxidase, which in turn results in premature ethylene production and petal senescence. This
“wound” induced gene expression may explain why carnation flowers tend to last longer
on the plant as compared with harvested flowers.
- C. Future Plans Covered by the Endowment Grant:
- The identification of several genes encoding ethylene biosynthetic enzymes will allow usto study the regulation of their expression. We will conduct experiments over the course of
the next year to identify cellular factors responsible for the regulated expression of these
genes. In addition, we will generate genetically engineered plants carrying new genes
designed to inhibit the expression of ethylene biosynthetic enzymes. These plants will be
analyzed for their capacity to synthesize ethylene under various postharvest handling
practices and following pollination. In addition, we will assess the effects of these genes
on flower vase-life.
- D. Anticipated Benefits for Floral Industry:
- The significance of this work is that processes critical to the regulation of ethylenebiosynthesis in flowers are for the first time being studied at the molecular level. This
information lends itself to genetic approaches in an attempt to prevent the increase in
ethylene that is responsible for considerable loss in postharvest quality of our crops. While
the benefit to our industry may be more slow to realize as compared to more applied
efforts, it is likely to lead to long term solutions to postharvest handling problems.
