US-3260-01C Plant Protection

Characterization of fungal symbiotic lifestyle expression in Colletotrichum and generating non-pathogenic mutants that confer disease resistance, drought tolerance, and growth enhancement to plant hosts	Req: Budget	Duration
	$350,000	3 years

Rodriguez, R.J.	U Washington	WA
Freeman, S.	ARO

Proposal Abstract
Fungal plant pathogens are responsible for extensive annual crop and revenue losses throughout the world. To better understand why fungi cause diseases, we propose to study genetic and biochemical aspects of symbiotic lifestyle expression (mutualism, commensalism, parasitism) in the fungal genus Colletotrichum. We have demonstrated that wildtype C. magna isolates, pathogenic to cucurbits, can be converted by mutation from expressing a pathogenic lifestyle to symbionts expressing non-pathogenic lifestyles. One group of non-pathogenic mutants confers disease protection against pathogenic species of Colletotrichum, Fusarium, and Phytophthora; drought tolerance; and growth enhancement to host plants. These mutants have been defined as mutualists and disease resistance correlates to a decrease in the time required for hosts to activate defense systems when exposed to virulent fungi. We have isolated the DNA (pFSLm1) responsible for the conversion of C. magna to a mutualist and have used this DNA to convert other Colletotrichum species to mutualists by gene disruption. We will use pFSLm1 to perform gene disruptions on Colletotrichum species pathogenic to specific hosts in the US and Israel and generate non-pathogenic mutants. The mutants will be assessed for the ability to confer disease resistance, drought tolerance, and growth enhancement in greenhouse studies. In addition, genomic regions containing the fslm1 sequence will be compared in different Colletotrichum species by analysis of overlapping clones from l libraries. Clones containing the fslm1 sequences will also be used to perform expression studies during the establishment of symbiotic associations. The expected contribution of this research to agriculture in the US and Israel is threefold. Host-specific mutualists will confer the following to crop plants: 1 - disease resistance to reduce dependence on chemical fungicides; 2 - drought tolerance to reduce water needs for irrigation, and 3 - growth enhancement to increase crop yields.