Biology subjects

morel, j.-b.

Publications and source records attributed to morel, j.-b..

3 recordsLinked to original sources

bioRxiv2026

Population structure of the rice blast fungus Pyricularia oryzae in the context of elevated host heterogeneity

In a context where pathogen emergence threatens global food security, crop resistance to pathogens is crucial for preventing and controlling epidemics. Agrosystems with high intraspecific cultivated diversity are expected to better mitigate infectious diseases compared with homogeneous ones. However, the long-term impact of cultivated genotypic heterogeneity on pathogen populations is still under debate. The 1,300-year-old traditional agrosystem of the Yuanyang Terraces (YYT) in China exhibits an outstanding level of rice diversity. The rice blast fungus Pyricularia oryzae has been recorded in the area, making this area ideal for studying the impact of long term heterogeneous cultivation on plant-pathogen coevolution. In this study, we analysed 94 P. oryzae genomes from the YYT and compared them to 198 genomes representative of the worldwide diversity. We report elevated levels of genomic diversity of P. oryzae in the YYT. Whereas the worldwide diversity of this species is organized in four lineages, we detected seven lineages within the YYT, four of which are restricted to this area. The sampling dates of the YYT isolates (2009 to 2017) provided sufficient temporal signal to date nodes of the phylogenetic tree of isolates. Endemic lineages appeared to have arisen several centuries ago but later than the origin of the YYT themselves. We also detected recent introductions of worldwide lineages. Linkage disequilibrium analyses and in vitro cross experiments suggest that P. oryzae reproduces asexually in the YYT. These results suggest that long-term intraspecific crop diversity in the YYT has promoted the emergence and maintenance of a highly diverse, locally adapted pathogen population.

evolutionary biology↗

bioRxiv2025

Genome Sequencing of Rice Landraces from the Yuanyang Terraces Uncovers Ancient and Diverse Lineages of Indica Rice

High-yielding elite rice cultivars exhibit limited genetic variability, raising concerns about our capacity to sustain productivity in the face of changing biotic and abiotic threats. Meeting the challenges that lie ahead largely depends on our ability to make use of novel sources of genetic variation and re-engineer agrosystems. Here, we report on the evolutionary history and population genetic structure of 353 accessions representing 91 landraces from Chinas centuries-old Yuanyang terraces of rice paddies (YYT). We found that the indica YYT landrace population is genetically structured and exhibits high standard variation. Analysis of natural selection reveals that innate immunity genes have a marked difference in coevolutionary dynamics between modern and traditional rice, characterized by a stronger influence of directional selection, which reduces diversity, in modern varieties. Our study highlights the importance of preserving landraces and the need for targeted efforts to integrate the standing variation in landraces into new varieties.

evolutionary biology↗

bioRxiv2022

Unsuspected transcriptional regulations during rice defense response revealed by a toolbox of marker genes for rapid and extensive analysis of expression changes upon various environments

Since rice (Oryza sativa) is an important crop and the most advanced model for monocotyledonous species, acceding to its physiological status is important for many fundamental and applied purposes. Although this physiological status can be obtained by measuring the transcriptional regulation of marker genes, the tools to perform such analysis are often too expensive, non flexible or time consuming. Here we manually selected 96 genes considered as biomarkers of important processes taking place in rice leaves based on literature analysis. We monitored their transcriptional regulation under several treatments (disease, phytohormone inoculation, abiotic stress...) using Fluidigm method that allows to perform ~10 000 RT-QPCR reactions in one single run. This technique allowed us to verify a large part of known regulations but also to identify new, unsuspected regulations. Together, our set of genes, coupled to our data analysis protocol with Fluidigm brings a new opportunity to have a fast and reasonably cheap access to the physiological status of rice leaves in a high number of samples.

plant biology↗