The ripening process: Understanding the molecular mechanisms responsible for the genetic regulation of fleshy fruit is a major objective for fruit improvement. Fleshy Fruits are divided into two main categories depending on whether the ripening process is controlled or not by the gaseous phytohormone Ethylene. Climacteric fruits such as tomato, apple, pear, and banana are characterized by a ripening-associated increase of respiration and the production of ethylene. By contrast, non-climacteric fruits, such as grape, orange, strawberry and pineapple lack this ethylene-associated respiratory peak. The signaling pathways that drive the ripening process in this last class of fruits remain elusive although the combined action of ABA (Abscisic Acid), auxin, and sugar is suspected to be instrumental to the ripening initiation. In our lab, we use grape and strawberry as non-climacteric model to characterize the influence of these different plant growth regulators (ABA, auxin and sugar) with a particular focus on regulatory genes that trigger the major genetic reprogramming associated with the ripening process.
- We are currently validating the function of a regulatory gene Auxin Response Factor 4 or VitviARF4, part of the auxin signaling. This gene could be important to determine the timing of ripening initiation in grape berry. We delve into its role as main driver of gene regulation and its putative role as protein partner interacting with other ripening-related proteins such as ABA and sugar-related proteins. We are currently conducting gain and loss-of-function studies using the microvine system combined to an inducible promoter to induce or silence VitviARF4 and verify in the impact of altered expression on fruit composition.
- We are also interesting in the specific interplay between ABA, auxin and sugar during the ripening initiation at different biological layers. We are particularly interested by the impact of the phosphoproteome during the ripening.
Plant-Pathogen interactions: Crop losses due to pest and diseases are a major threat to incomes rural families and to food security. The growing human population will require a significant increase in agricultural production from staple food to more marginal crops economically valuable though. Changes in the climactic and environmental conditions are leading to the appearance of new diseases whereas genetic changes within pathogen have resulted in the loss of effective sources of resistance and making the increasingly ineffective use of fungicides and pesticides a major concern for the sustainability of the environment of agricultural ecosystem. In this particular context, the identification of new resistance genes is mandatory. This will only be possible by a better understanding of the plant-pathogen interactions in order to produce either by conventional or molecular breeding new crop varieties that will carry a full or partial resistance without affecting other agronomically important traits. The interactions between a plant and its pathogen involve two-way communication by the ability of the plant to recognize and defense itself against a pathway and the capacity of the pathogen to circumvent the biology of the plant or to use it to its own benefit. Among pathogens, plant viruses are extremely harmful to the production of vegetable, fruits, and cereal crops.
- In the lab we are studying the interaction of virus and fruit development with a major emphasis on the effects of the virus on transcriptional and post-transcriptional regulation of fruit ripening. We are currently interested in using the CRISPR technology in conjunction with the microvine to validate the effectiveness of potential resistance genes that could mitigate the viral spread.
Signaling and communication in plants: Long-distance signaling and communication between different organs of a plant is essential not only for the development and growth of the plant body, but also to adequately respond to unfavorable growing conditions. Higher plants coordinate and integrate the growth and development of their tissues and organs via sensory systems that result in the production of chemical and electrical signals that are transported from one part of the plant to another. We are using two main plant models in the lab to study this topic.
- The first one is grapevine in the context of root-to-shoot and shoot-to-root communications between several rootstock and scion genotypes in condition of high nitrogen availability. The use of trans-grafting procedure, genetically grafted material, will be explored to understand the nature of these communications.
- The second model is Brachypodium Distachyon. Our research question is oriented towards the influence of Strigolactone, a plant growth regulator, on root and shoot branching.