LAUSR

Astragalus adsurgens Pall., a perennial legume native to China, is commonly used as a forage crop. Due to its high rate of legume production and the fact that it assists in soil and water conservation, it has great value for sustainable development of grasslands in arid and semi-arid regions. However, to date, little is known regarding the A. adsurgens genome, and no studies have determined whether it would be possible to improve the germplasm of A. adsurgens via genetic modification. In this study, we used a RNA-seq protocol to generate a de novo transcriptome including 151,516 unigenes of A. adsurgens. We compared the transcriptomes of A. adsurgens with different growth habits (prostrate/erect) and identified 14,133 single nucleotide polymorphism sites (SNPs) in 8,139 unigenes. The different expression genes (DEG) analysis suggested that 10,982 unigenes were up-regulated in prostrate plant relative to erect plant, as well as 10,607 unigenes were down-regulated. Of the 21,589 DEGs, Unigene72782_All (LAX4) and CL12494.Contig3_All (TIR1), the known auxin transporter and transport inhibitor genes, respectively, were predicted to influence the growth habit of A. adsurgens, which were verified by qRT-PCR in various phenotypes. These results raise a hypothesis that auxin transporting was more active in prostrate plant than that in erect plant, resulting in an asymmetric distribution of auxin that affected the growth habit of A. adsurgens. Overall, this study may serve as a basis for future research on the key genes exploration in A. adsurgens and may deepen our understanding of the molecular mechanism regulating plant growth habit.