Progress 05/01/09 to 04/30/12
Outputs
Progress Report Objectives (from AD-416): 1. Characterize ripening behavior and ethylene evolution of 6-10 cultivars at defined developmental stages. 2. Examine expression patterns of ACS3 and its effect on other ethylene biosynthesis and perception related genes. 3. Explore the potential allelic polymorphism for ACS3 locus for potential functional molecular marker generation. Approach (from AD-416): 1. Defining the ripening stages by physiological studies on selected cultivars and collecting corresponding peel and cortex tissues. 2. Gene expression analysis on ACS3 gene and other genes in ethylene response pathways by quantitative RT-PCR. 3. Genome-walking and bioinformatics analysis for detecting potential ACS3 gene polymorphism. This serves as the final report. This project relates to objective 1 of the associated in-house project which seeks to identify factors that influence postharvest fruit quality and development of market limiting physiological disorders. Additional details of research can be found in the report for the parent project 5350-43000-006-00D, Genetic, metabolic, and physiological factors regulating deciduous tree fruit quality. Apple fruit ripening behaviors closely influence fruit quality such as fruit firmness and postharvest firmness retention. Storability of apple fruit is ultimately associated with industry profitability and sustainability. Ethylene plays an important role in apple fruit development and it is produced by the activity of several proteins. A protein active in the first step of ethylene production determines how much ethylene is produced. Assessment of the gene for this protein during maturation of 12 apple cultivars indicates the gene acts as a ripening �accelerator� causing different apple varieties to begin to ripen at different times during the fall. The results from this study could potentially be utilized to develop tools for breeders to design new apple varieties with desired ripening characteristics.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) 1. Characterize ripening behavior and ethylene evolution of 6-10 cultivars at defined developmental stages. 2. Examine expression patterns of ACS3 and its effect on other ethylene biosynthesis and perception related genes. 3. Explore the potential allelic polymorphism for ACS3 locus for potential functional molecular marker generation. Approach (from AD-416) 1. Defining the ripening stages by physiological studies on selected cultivars and collecting corresponding peel and cortex tissues. 2. Gene expression analysis on ACS3 gene and other genes in ethylene response pathways by quantitative RT-PCR. 3. Genome-walking and bioinformatics analysis for detecting potential ACS3 gene polymorphism. This project relates to objective 1 of the associated in-house project which seeks to identify factors that influence postharvest fruit quality and development of market limiting physiological disorders. Apple fruit ripening behaviors closely influence fruit quality such as fruit firmness and the postharvest firmness retention. Storability of apple fruit is ultimately associated with industry profitability and sustainability. Ethylene plays an important role in apple fruit development and its biosynthesis is catalyzed by two enzymes, i.e. ACS (1-aminocyclopropane-1- carboxylate synthase) and ACO (1-aminocyclopropane-1-carboxylic acid oxidase). The gene form (or alleles) of MdACS1 and MdACS3, are one of genetic determinants of apple ripening and texture. Results of ACS3 expression analysis during 8-week on-tree maturation and ripening among 12 apple cultivars suggest cultivar-specific dynamics of MdACS3 expression acts as an �accelerator� of ripening and texture changes. Unlike MdACS1, the expression of MdACS3 was stimulated by 1-MCP treatment, indicating a negative feedback regulation mechanism. The results from this study could potentially be utilized to develop molecular tools for selecting desired genotypes associated with ripening season, and perhaps as a guide in predicting postharvest behavior of new apple cultivars such as the timing for 1-MCP treatment. Results from the second part of the project utilizing pre-harvest 1-MCP (Harvista�) application and postharvest 1-MCP treatments to characterize ethylene biosynthetic and receptor genes in �Golden Delicious� apples are currently being summarized. Progress is monitored through annual submission of written reports to the funding organization.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) 1. Characterize ripening behavior and ethylene evolution of 6-10 cultivars at defined developmental stages. 2. Examine expression patterns of ACS3 and its effect on other ethylene biosynthesis and perception related genes. 3. Explore the potential allelic polymorphism for ACS3 locus for potential functional molecular marker generation. Approach (from AD-416) 1. Defining the ripening stages by physiological studies on selected cultivars and collecting corresponding peel and cortex tissues. 2. Gene expression analysis on ACS3 gene and other genes in ethylene response pathways by quantitative RT-PCR. 3. Genome-walking and bioinformatics analysis for detecting potential ACS3 gene polymorphism. Documents Trust with WTFRC. Log 37941. This project is related to objective 2 of the associated in-house project which is to identify the genetic factors regulating fruit texture. Understanding the genetic control of ethylene, the natural signal that regulates apple fruit ripening, will facilitate the development of tools to enhance apple breeding as well as postharvest fruit quality management. Ethylene�s role in regulating fruit ripening and quality is indisputable. A major ethylene biosynthesis gene, MdACS1, has been well characterized, but little is known regarding the role of MdACS3, another ethylene biosynthesis gene that is expressed prior to the onset of ripening. ARS scientists at the Tree Fruit Research Laboratory used 15 apple cultivars to evaluate ripening and ethylene production at harvest and after cold storage. The results indicated two different expression patterns of MdACS3 among these cultivars, and these expression in general correlates with ripening season and fruit storability. For example, �Granny Smith�, �Jazz� and �Pink Lady�, which are generally store well and respond well to the ethylene inhibitor 1-MCP, have low MdACS3 expression. �Golden Delicious�, �McIntosh�, and �Honeycrisp� showed high MdACS3 expression at harvest and normally don�t respond as well to 1-MCP. The results have been summarized in a manuscript and submitted to a peer reviewed journal. Additional work on the role of MdACS3 expression and its relationship to apple postharvest quality is underway. Monitoring Activities: Progress is monitored through annual submission of written and oral progress reports to the funding agency.
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) 1. Characterize ripening behavior and ethylene evolution of 6-10 cultivars at defined developmental stages. 2. Examine expression patterns of ACS3 and its effect on other ethylene biosynthesis and perception related genes. 3. Explore the potential allelic polymorphism for ACS3 locus for potential functional molecular marker generation. Approach (from AD-416) 1. Defining the ripening stages by physiological studies on selected cultivars and collecting corresponding peel and cortex tissues. 2. Gene expression analysis on ACS3 gene and other genes in ethylene response pathways by quantitative RT-PCR. 3. Genome-walking and bioinformatics analysis for detecting potential ACS3 gene polymorphism. Documents Trust with WTFRC. Log 37941. Significant Activities that Support Special Target Populations No progress to date due to the fact that the money for this project was received in June 2009. All the money was added to a SCA and the cooperator for the SCA just signed the agreement on 9/22/2009.
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