3.2 Gene expressions
The gene expressions and KEGG functional enrichment results for each region under different soil moisture treatments were shown in Figs. 1 & 2. For individuals from the eastern region, gene expressions were significantly enriched in photosynthesis-antenna proteins, RNA degradation, spliceosome, and photosynthesis (Figs. 2a-c). Specifically, gene expressions were enriched in sulphur metabolism pathway and phenylalanine, tyrosine and tryptophan biosynthesis pathway under the light drought treatment (Fig. 2b), and in porphyrin and chlorophyll metabolism, thiamine metabolism, fructose and mannose metabolism pathways under the heavy drought treatment (Fig. 2c).
For individuals from the middle region, gene expressions were mainly enriched in photosynthesis-antenna proteins, RNA degradation, spliceosome, and photosynthesis (Figs. 2d-f). Specifically, gene expressions were enriched in basal transcription factors, circadian rhythm-plant, and ribosome biosynthesis in eukaryotes pathways under the heavy drought treatment (Fig. 2f).
For individuals from the western region, gene expressions were mainly enriched in photosynthesis-antenna proteins, spliceosome, and photosynthesis (Figs. 2g-i). Specifically, gene expressions were enriched in RNA degradation under the light drought treatment (Fig. 2h), and in protein processing in endoplasmic reticulum and ubiquitin mediated proteolysis pathways under the heavy drought treatment (Fig. 2i).
Results of heatmaps and the dendrogram showed that individuals from the eastern and middle regions showed higher similarity and grouped into one subgroup under the same soil moisture treatments. Individuals from the eastern region under the heavy drought treatment showed higher similarity with those from two other regions under the light drought treatment. Individuals from the western region under both control and light drought treatments showed higher similarity, and this subgroup was clustered with another subgroup that included the eastern and middle regions under the control treatment (Fig. 3).