Molecular Mechanisms determining Seed Longevity
Understanding how seeds remain viable for years and how they deteriorate, and why some seeds remain viable longer than others is a fascinating subject that can be studied from the scientific point of view, but also with an enormous potential in oriented research, given the economic importance of the seed market and the low seed life span of many species. Seed longevity can be seen as a process where plant responses to both biotic and abiotic stresses are intermingled. Contrary to classical stress situations, is not the plant, but the metabolically inert dry seed which has to be prepared and resist the stressful conditions. Also peculiar is the fact that the new germinating seed has to cope with the consequences of a stress that occurred to the embryo in the past, not in real time. Moreover, it is an aspect of stress biology that integrates passive and active responses, protection and repair, and where development (seed maturation, germination, plant establishment) and stress research are combined.
In the last years, our group has initiated the search of new players contributing to the genetic component of seed longevity. Using the model plant Arabidopsis thaliana, we want to identify genes relevant for resistance to seed deterioration, and to characterise their mode of action. From the scientific point of view, our interest is to understand how the seed is prepared during maturation to cope with aging, and how the emerging seedling repairs the damage accumulated during the aging period. Currently, several processes are being studied in detail: 1) How the environment during seed development influence seed longevity and other seed properties. We pretend to unravel the effects of the environment during seed development on seed longevity, and to identify the regulatory pathways transducing environmental signals and the downstream processes and genes involved. Our results will allow a major control of seed viability, allowing future improved agricultural practices and seed preservation management programmes. 2) What is the role of flavonoids in seed protection and their connection with testa development. Besides their supposed as antioxidants, these compounds may be acting as signalling molecules 3) We also use natural variation to identify new processed involved in seed longevity. From the oriented point of view, we are interested in knowing why and how different industrial seed treatments and coatings are affecting seed quality, and providing suggestions to seed companies in order to improve seed life span and seed quality.
Bacterial Effector and Plant-Pathogen Interaction
The discovery of new translocated plant effectors and the characterization of their activities, or the mechanisms by which they are recognized by the plant immune system is a second line of research in my group. Here, we are focused mainly on citrus-pathogen interactions. Xanthomonas citri is the causal agent of citrus canker. This bacterium uses transcriptional-activator like effectors (TALEs) to facilitate infection. The way the plant activates defence responses in response to specific TALEs has been investigated in our group during the last years. Our main objective here is to identify R genes triggering a hypersensitive response mediated by TALE-avirulence factors. HLB (Huanglongbing) is a devastating disease in Citrus, caused by bacteria of the Liberibacter genus. We are testing the role of putative bacterial effectors using heterologous systems, and using transcriptomics to characterize the plant responses to these bacteria in susceptible and resistant interactions.