Fig. 1: Comparison of transcriptomic guanine (G) frequencies and RNA G-quadruplex frequencies exhibit climatic signatures of plant adaptation.

a Scatter plot showing the frequency of each nucleotide (A: adenine, U: uracil, C: cytosine, and G: guanine) in transcriptomes of 906 land plants from the 1000 Plants (1KP Initiative)⁶. n = 556, 107, 80, 71, 21, 71 for dicots, monocots, gymnosperms, ferns, lycophytes and bryophytes, respectively. b Heat plot showing the Pearson Correlation Coefficient (PCC) between transcriptomic nucleotide frequency and bioclimatic variables of plant habitats. The frequencies of the four nucleotides were calculated in 906 land plants derived from the transcriptomes of the 1000 Plants (1KP). The corresponding plant habitats were sourced from the Global Biodiversity Information Facility (GBIF). The bioclimatic variables of these plant habitats were derived from the WorldClim database, i.e., BIO1: annual mean temperature (for full details see Materials and Methods), as explained by WorldClim (https://www.worldclim.org/). c Bar plot showing the counts of significant PCCs between transcriptomic nucleotide frequency and temperature bioclimatic variables. PCCs with a P value less than a threshold of 0.01 were retained. d RNA G-quadruplex (RG4) frequencies in major clades of land plants. Land plants with over 100 occurrences in Global Biodiversity Information Facility (GBIF)⁷ were included (see Methods). n = 277, 43, 30, 30, 10, 43 for dicots, monocots, gymnosperms, ferns, lycophytes and bryophytes, respectively. The corresponding annual mean temperatures for habitats of plant species were color-coded. e Heat plot showing the Pearson Correlation Coefficients (PCCs) between RG4 frequency in plant transcriptomes and associated bioclimatic variables related to plant habitats. PCCs with a P value less than a threshold of 0.01 were retained. Plant habitats were sourced from the GBIF, while associated bioclimatic variables were derived from the WorldClim database (full details see Methods).