Development and Use of an Innovative TASSEL Tagging System to Identify "Green Genes"

Cornell Univ - State: Awds Made Prior May 2010, Ithaca NY

Investigators

Abstract

PI: Susheng Gan, PhD, Cornell University Leaf senescence is an integral part of leaf development that involves a massive operation of programmed cell death. During senescence a leaf loses its photosynthetic capability. Leaf senescence thus limits crop yield and reduces the postharvest storage and shelf life of many vegetables. Nutrients such as vitamin C and proteins are also degraded during leaf senescence. In addition, a senescing tissue becomes more susceptible to pathogens, some of which may produce toxins. However, the mechanisms underlying leaf senescence are not well understood. The objective of this project is to utilize a newly developed innovative functional genetics approach called TASSEL (transposon-associated, senescence-specific enhancer-linked) activation tagging to identify senescence-suppressing genes or "green genes". In the TASSEL system, four copies of a senescence-specific enhancer are placed between the ends of the maize transposon Ds. In the presence of transposase, the senescence enhancer-laden Ds element transposes to different sites within the plant genome. At the onset of senescence, the senescence-specific enhancers will activate plant genes adjacent to the Ds insertion site. If the activation of a gene is sufficient to inhibit senescence, the affected cells will remain green, giving rise to a "green island", while the rest of the leaf becomes yellow. The activated "green genes" will be cloned from "green island" tissues using various molecular tools. Genes identified in tobacco plants can be readily used to identify orthologs in important crops including other members of the Solanaceae (tomato, pepper, eggplant, potato) and can be immediately used to manipulate senescence for agricultural improvement. Therefore, this research will have a profound impact on food production and safety. Most importantly, this research is an important educational platform for training young plant biologists. It will be integrated into a graduate-level course called "Plant Senescence" at Cornell, and one graduate student and one postdoctoral associate will be directly involved in the research.