U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Crops Pathology and Genetics Research: Davis, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Outreach Events
                        UC Davis Picnic Day
                                    Kinders go to College
                                    STEM Girls
                                    Future Scientist Program
                                    Agriculture Future of America
                                    Wallace-Carver Fellowship
                                    Young Scholars Program
                                    Annual Awards Banquet
                    About Us
                        About Us
                                    Our Mission
                                    Principal InvestigatorsSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Davis, California Crops Pathology and Genetics Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications
- Etiology and Biology of Tree Crop Diseases
- Rice Genetics
- Sustainable Floriculture
- Sustainable Viticulture

Title:   Author  item
                                            ESTRADA-MELO, ALEJANDRO - University Of Californiaitem
                                            MA, CHAO - University Of Californiaitem
                                            REID, MICHAEL - University Of Californiaitem
                                            Jiang, Cai-Zhong
  Submitted to: Horticulture Research
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 2/26/2015
                                    Publication  Date: 4/8/2015
                                    Publication URL: http://www.nature.com/articles/hortres201513Citation: Estrada-Melo, A.C., Ma, C., Reid, M.S., Jiang, C. 2015. Overexpression of an ABA biosynthesis gene using a stress inducible promoter enhances drought resistance in petunia. Horticulture Research. doi: 10.1038/hortes.2015.13.Interpretive Summary: Among the different stress conditions that plants frequently encounter, the abiotic stress, drought, constitutes one that is responsible for major worldwide environmental constraints for agricultural crops. Climate change will increase the occurrence of drought periods in some parts of the world, therefore improving plant growth under water-limited conditions will become one of the most challenging tasks for growers of all plant crops.
Plants are sessile and therefore need to cope effectively with environmental stresses. Plant growth regulators often play a role as intermediaries between the perception of an environmental stress and the ultimate morphological response. The plant hormone Abscisic acid (ABA) is involved in seed maturation and dormancy processes, but also enables plants to survive stresses such as drought, cold and high salt in soils. Water stress resulted in an increased ABA levels in shoots followed by stomata closure which decrease water loss by reducing transpiration. ABA also acts as a signal for the induction of dehydration tolerance genes, that in addition to protect the cells from stress, some of these osmotic responsive (OR) genes, that are activated under stress conditions, regulate downstream genes for signal transduction.  These genes are involved in the synthesis of Late Embryogenesis Abundant (LEA) proteins, that are associated in desiccation tolerance during seed maturation, in the water transporters such as aquaporins, in the detoxification enzymes like superoxide dismutase, catalase, etc, in protein kinases, in phosphatases as well as in transcription factors that act as regulatory molecules. 
Experiments in transgenic plants have demonstrated that NCED is a key rate limiting step in ABA biosynthesis, and its overexpression resulted in ABA accumulation and increased drought tolerance in tomato (Solanum Lycopersicon), Arabidopsis thaliana and tobacco (Nicotiana tabacum). These studies all used constitutive promoters to drive expression of NCED genes, with negative pleiotropic effects on plant growth and development. It is therefore necessary to use a promoter which will not result to pleiotropic effects or at least reduce the negative effects of the constitutive promoter.
In the present study, we used the stress-inducible promoter Rd29A to drive LeNCED1 expression.  Under well-watered conditions, transgenic plants growth was similar than wild-type and the effect of seed dormancy was not observed. When the transgenic plants were exposed to water stress, resulted in an increased NCED mRNA, an elevated ABA content in the leaves and in a significant increase in drought tolerance compared to the wild-type. The transgenic petunia plants also displayed the expected decrement in stomatal conductance, transpiration and photosynthetic rate compared to the wild type. Our data suggest that under water stress is possible to reduce water loss by transpiration in Petunia plants by using a stress inducible promoter which turn on the expression of LeNCED, increases ABA content, induces stomata closure and enhances drought tolerance; and when favorable conditions are present, the LeNCED expression is turned off, thus avoiding the negative phenotypic effects of using a constitutive promoter.
                                Technical Abstract: Plants respond to drought stress by closing their stomata and reducing transpirational water loss. The plant hormone abscisic acid (ABA) regulates growth and stomatal closure particularly when the plant is under environmental stresses. One of the key enzymes in the ABA biosynthesis of higher plants is 9-cis-epoxy-carotenoid dioxygenase (NCED). It has been shown in tomato that the overexpression of NCED using constitutive promoter resulted in increased ABA which induced stomata closure and increased water use efficiency, however high levels of ABA accumulation also resulted in increased seed dormancy, intervenial leaf flooding and reduced plant growth. Here the LeNCED1 gene was overexpressed in petunia plants under the control of a stress inducible Rd29A promoter. Under well-watered conditions, transgenic plants growth was similar than wild-type and the effect of seed dormancy was not observed. When the transgenic plants were exposed to water stress, resulted in an increased NCED mRNA, an elevated ABA content in the leaves and in a significant increase in drought tolerance compared to the wild-type. The transgenic petunia plants also displayed the expected decrement in stomatal conductance, transpiration and photosynthetic rate compared to the wild type. Our data suggest that under water stress is possible to reduce water loss by transpiration in Petunia plants by using a stress inducible promoter which turn on the expression of LeNCED, increases ABA content, induces stomata closure and enhances drought tolerance; and when favorable conditions are present, the LeNCED expression is turned off, thus avoiding the negative phenotypic effects of using a constitutive promoter.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov