R Gene Counts Correlate with Precipitation
The significant correlation between net precipitation rate, as estimated by average CMI, and the number of R genes in a plant’s genome, detected in both the Illumina short-read dataset as well as the underpowered PacBio long-read libraries (n=9), suggests evidence of possible genomic adaptation for higher pathogen load. In fact, the steeper relationship of R gene number and CMI observed with the PacBio long-read libraries suggests that the Illumina dataset underestimates the strength of this relationship. The trend does not appear to be driven by either TNLs or CNLs, for which the results conflict between the Illumina and PacBio datasets. Genes of type TNL, or those containing a toll-interleukin-like receptor in their N-terminal domain, don’t differ significantly according to CMI. A stronger understanding of the relationship between climate factors and the evolution of these two subtypes of R genes remains to be investigated.