Stable Isotope Probing-RNA Strategy to Study Plant/Fungus Interactions.

The use of stable-isotope probing (SIP) allows tracing specific labeled substrates into fungi leading to a better understanding of their role in biogeochemical cycles and their relationship with their environment. Stable isotope probing combined with ribosomal RNA molecule, conserved in the three kingdoms of life, and messenger RNA analysis permits the linkage of diversity and function. Here, we describe two methods designed to investigate the interactions between plants and their associated mycorrhizal compartment by tracing carbon flux from the host plant to its symbionts.

Differential selection pressures exerted by host resistance quantitative trait loci on a pathogen population: a case study in an apple × Venturia inaequalis pathosystem.

Understanding how pathogens evolve according to pressures exerted by their plant hosts is essential for the derivation of strategies aimed at the durable management of resistant cultivars. The spectrum of action of the resistance factors in the partially resistant cultivars is thought to be an important determinant of resistance durability. However, it has not yet been demonstrated whether the pressures exerted by quantitative resistance are different according to their spectrum of action. To investigate selection pressures exerted by apple genotypes harbouring various resistance quantitative trait loci (QTLs) on a mixed inoculum of the scab disease agent, Venturia inaequalis, we monitored V. inaequalis isolate proportions on diseased apple leaves of an F1 progeny using quantitative pyrosequencing technology and QTL mapping. Broad-spectrum resistances did not exert any differential selection pressures on the mixed inoculum, whereas narrow-spectrum resistances decreased the frequencies of some isolates in the mixture relative to the susceptible host genotypes. Our results suggest that the management of resistant cultivars should be different according to the spectrum of action of their resistance factors. The pyramiding of broad-spectrum factors or the use of a mixture of apple genotypes that carry narrow-spectrum resistance factors are two possible strategies for the minimization of resistance erosion.