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.