4.1 Drought adaptation differences of S. krylovii among different
regions
In this study, the factor of seed source of region showed significant
effects on growth and physiological traits (Table 2), which was
consistent with the previous studies (Klein & Mitchell, 2024). In
addition, under the heavy drought treatment, unique enriched pathways
were found of individuals from each region.
For individuals from the eastern region under heavy drought treatment,
specific KEGG enriched pathways included thiamine metabolism, fructose
and mannose metabolism (Fig. 2c), and these metabolism pathways are
found to be related to drought tolerance in several researches. Li et
al. (2022) have shown that exogenous application of thiamine can enhance
plant stress tolerance by activating stress-responsive genes and calcium
signal transduction. Ye et al. (2020) have found that Pterocarya
stenoptera initiates the thiamine metabolism pathway under drier air
stress condition using 6-month-old seedlings. You et al. (2019) have
shown that genes for fructose and mannose metabolism are up-regulated in
drought-tolerant sesame to cope with stress condition.
For the individuals from the middle region under heavy drought
treatment, specific KEGG enriched pathways included basal transcription
factors, and circadian rhythm-plant (Fig. 2f). Circadian rhythm-plant
pathway is common for species under the drought condition (Wang et al.,
2021). Transcription factors pathway is an important class of regulatory
proteins that plays important roles in regulatory networks and signaling
pathways of plant development and abiotic stresses (Yang et al., 2017);
however, the basal transcription factors pathway related to drought
adaptation was not common in previous studies. Therefore, more specific
researches on transcription factors pathway are needed for S.
krylovii in the future.
For the individuals from the western region under heavy drought
treatment, specific KEGG enriched pathways included protein processing
in endoplasmic reticulum, ubiquitin mediated proteolysis (Fig. 2i). This
finding was consistent with the previous studies. Moon et al. (2018)
have found that the drought tolerance mechanisms of the drought-tolerant
potato (Solanum tuberosum L.) are related to protein processing
in the endoplasmic reticulum as well as the photosynthetic-antenna
protein. Zhang et al. (2021) have shown that endoplasmic reticulum and
capacity of ubiquitin-mediated proteolysis pathways play important roles
in gene expression of Bt cotton under high-temperature and water deficit
stress conditions.