Abstract:

Phenotypic traits of the natural Arabidopsis thaliana population represent its adaptation in natural environments. Comparison of phenotypic traits among different populations can provide important clues for understanding phenotypic variation and formation processes of A. thaliana. It is an important aspect that cannot be ignored for phenotypic adaptation and evolution of natural A. thaliana populations. We investigated nine phenotypic traits of 10 A. thaliana populations located in the northern Tianshan, Altai, and Tarbagatay mountains of Xinjiang, and compared variations in phenotypic traits in natural conditions at micro-, local- and regional-scales. Our results showed that different traits respond differently to environm- ental changes. Plant height, plant weight, root weight, root length, single fruit weight and fruit dehiscence force differed among populations at the three scales. However, branching number and fruit length did not differ among populations with low phenotypic differentiation coefficients. Plant weight, root weight and fruit number per plant all showed a consistent integration pattern at different scales, potentially reflecting the importance of physiological functional integration in A. thaliana. These three phenotypic characteristics also exhibited obvious adaptation to local environment. At the same time, we found that the extent of integration of phenotypic traits varied between local and regional scales. Cluster analysis showed that different populations from the same region grouped together, further showing that the phenotypic traits of A. thaliana were strongly influenced by the micro-scale environmental factors. Mantel test showed that the variations of plant height, plant weight, root weight, single fruit weight, fruit length and fruit dehiscence force significantly correlated with geographic distance, while the variations of branch number and root length did not. We therefore concluded that phenotypic variations of A. thaliana were strongly affected by the micro- scale environmental factors. However, not all the phenotypic traits were associated with the original habitat climate.

Key words: Arabidopsis thaliana, phenotypic traits, phenotypic integration, natural population, adaptation