Les séminaires ont lieu sur le Campus Montpellier Institut Agro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 29 septembre à 14h
Blanca San Segundo
(Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Barcelona, Spain)
Crosstalk between Nutrient Signaling Pathways and Immune Responses in Plants
Plants in their natural habitats are simultaneously confronted to a range of biotic and abiotic stress factors. Crosstalk between responses induced by a particular type of stress might have a positive or negative impact over other stress. However, most research on plant responses to environmental stress has been conducted on plants subjected to an individual stress. Understanding the molecular mechanisms underlying disease resistance under nutrient stress conditions is essential for the development of effective strategies aiming at combating pathogen infection.
MicroRNAs (miRNAs) are short non-coding small RNAs that direct post-transcriptional gene silencing through cleavage or translational repression of target genes. Plant miRNAs play a critical role in controlling diverse developmental processes and adaptation to environmental stress, both biotic and abiotic stresses. We investigate the involvement of miRNAs as hubs for the control of nutrient homeostasis and immunity in plants (rice, Arabidopsis). Our research is focused on miRNAs controlling phosphate (miR399, miR827) or iron (miR7695) homeostasis. In rice, high Pi fertilization, miR399 overexpression or miR827 overexpression increases Pi content in leaves and enhances susceptibility to infection by the rice blast fungus Magnaporthe oryzae, which is consistent with a weaker activation of defense-related genes. Contrary to this, Pi accumulation in Arabidopsis caused by miR399 overexpression or high Pi fertilization is associated with stronger immune responses and resistance to infection by fungal pathogens. On the other hand, treatment with Fe, as well as miR7695 activation, is accompanied by strong induction of defense responses and resistance to M. oryzae infection. During pathogen infection, iron accumulates at the sites of pathogen entry and in cells surrounding infection sites. These data support that Pi, when in excess, compromises defense mechanisms, while local accumulation of Fe potentiates defense responses and increases blast resistance in rice plants. This information provides a basis to rational optimization of fertilizer and pesticide use in rice production.
Contact : Doan-Trung Luu
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