Credit Seminar on Plant- Derived Sucrose is a Key Element in the Symbiotic Association Between Trichoderma virens and Maize Plants

Fungal species belonging to the genus Trichoderma colonize the rhizosphere of many plants, resulting in beneficial effects such as an increased resistance to pathogens and greater yield and productivity. Trichoderma virens secretes the highly effective hydrophobin like elicitor Sm1 that induces systemic disease resistance. Plant-derived sucrose is an important resource provided to Trichoderma cells and is also associated with the control of root colonization. The identification and characterization of an intracellular invertase from Trichoderma virens (TvInv) is important for the mechanisms that control the symbiotic association and fungal growth in the presence of Sucrose. Gene expression studies revealed that the hydrolysis of plant-derived sucrose in T. virens is necessary for the upregulation of Sm1, that systemically activates the defense mechanisms in leaves. It has been determined that as a result of colonization of maize (Zea mays) roots by T.virens, photosynthetic rate increases in leaves and the functional expression of tvinv is crucial for such effect. In agreement, the steady-state levels of mRNA for Rubisco small subunit and the oxygen-evolving enhancer 3-1 has been shown to be increased in leaves of plants colonized by wild-type T. virens. It has been concluded that during the symbiosis, the sucrolytic activity in the fungal cells affects the sink activity of roots, directing carbon partitioning toward roots and increasing the rate of photosynthesis in leaves. A discussion of the role of Sucrose in controlling the fungal proliferation on roots and its pivotal role in the coordination of plant-microbe associations is provided.

Name: Kolli Vidyalatha, M.Tech II Year
Guide Name: Dr.Usha
Venue: Room No.701B
Time: 3.00pm
Date: 4.09.12