Molecular and evolutionary analysis of the RPP1-SRF3 incompatible interaction between Central Asian and North European A. thaliana populations (EVOIMMUNITY)
R+D program of Scientific and Technical Excellence 2013
Ministry of Economy and Competitiveness, Spain
PI: Ruben Alcazar
The study of post-zygotic Bateson-Dobzhansky-Muller (BDM) hybrid incompatibilities in model species is gaining novel insights into the genetic, molecular and evolutionary basis of reproductive isolation barriers potentially leading to speciation. Genetic divergence of the plant immune system drives BDM incompatibility between Arabidopsis thaliana populations. During evolution, incompatible alleles accumulate and become fixed in parental lines by selection or drift. Understanding the molecular and evolutionary basis for the occurrence of such allelic mismatches between Arabidopsis thaliana wild populations is the objective of the current proposal. We previously identified a two-loci genetic interaction between the North European Landsberg-erecta (Ler) and Central Asian (Kashmir-2 and Kondara) populations of Arabidopsis thaliana that leads to constitutive activation of plant immunity, stunted growth and sterility at moderately low temperature (14-16ºC). We mapped the causal loci to a cluster of RPP1 (Recognition to Peronospora Parasitica 1)-like TIR-NB-LRR (Toll-Interleukin1 Receptor-nucleotide binding-Leucine-rich repeat) immune receptor genes in Ler that are incompatible with Kas-2 or Kond forms of the receptor-like kinase SRF3 (Strubbelig Receptor Family 3). The recent discovery by us of a wild Arabidopsis thaliana local population genetically most similar to Ler will enable to study the evolution of RPP1-like Ler genes in the wild and the occurrence of signatures for selection at this locus. Through genetic approaches, we will investigate which RPP1-like Ler gene(s) within the cluster is causal for incompatibility with Kas-2 and Kond SRF3 forms. We will determine the fitness conferred by RPP1-like Ler genes using transgenic approaches and wild populations segregating for the presence/absence of the RPP1-like Ler cluster. Under a molecular perspective, we will define the molecular basis of the RPP1-SRF3 genetic interaction which is essential to establish guard-guardee relationships as drivers of BDM incompatibility involving the immune system.
GENETICS OF TEMPERATURE MODULATION OF PLANT IMMUNITY (DISEASENVIRON)
Funded under 7th Framework Programme
Research area:FP7-PEOPLE-2011-CIG Marie-Curie Action
Career Integration Grants
Grant holder: Ruben Alcazar
During their life cycle, plants are exposed to microbes in soil and leaf surfaces that can cause disease and result in crop losses and pathogen spread. Even though chemical treatment and genetic engineering have been successfully applied to combat disease, it is increasingly being recognized that understanding the natural co-evolution of plants with pathogens will provide new leads for pest regulation and, potentially, anticipate evolving pathogen strategies to evade recognition and cause disease. This new perspective requires understanding fundamental questions in the co-evolution between plants and pathogens using a combined genetic and molecular approach, and studying natural populations of plants that may be locally adapted. During the co-evolution with pathogens, plants have evolved mechanisms to distinguish foe from a benign or potentially beneficial microorganism and to induce appropriate defence reactions and anti-microbial molecules.
However, activation of pathogen defence is likely costly for the plant as evidenced in growth defects exhibited by plants with constitutive activation of immune responses. As consequence, a proper balance between growth, reproduction and immune response had to be achieved during evolution, leading to an inducible immune system influenced by environmental fluctuations. The recent discovery of temperature-dependent hybrid incompatibilities in Arabidopsis thaliana allows at identifying genetic components at the intersection between plant immunity and the environment. Studying the molecular and genetic basis for such incompatibilities should provide novel insights into mechanisms underlying temperature regulation of plant immunity and local adaptation shaping genetic variation of immune-related genes.
Additional funding support