Transcriptomic and metabolomic dissections of the drought resistance traits of a soya bean landrace

Regional Soybean landrace accessions with diverse genetic backgrounds are valuable resources for the efforts of soybean breeding programs, as only limited germplasm resources are currently available for breeding the best cultivars. To explore the molecular basis of drought tolerance traits of regional soybean collections, a localsoybean landrace LX together with the standard wild type William82 were chosen to perform the multi-omics analysis with the aim to understand the molecular basis of the desired traits of LX. Firstly, the germination potential of LX was investigated which confirmed the previous report that LX germinated better at drought stress conditions. Additionally, LX plants accumulated more anthocyanin at both normal and stress conditions, and exhibited better resistance to drought treatment comparing to William82. When grown at the same condition, the LX plants are greener than control lines and contain more chlorophyll. Collection of biochemical measurements all indicated that LX is more physiologically adaptive to stress conditions. Using untargeted mass spectrometry analysis in combination with transcriptomics analysis, we revealed the chemical diversity and genetic basis underlying the overall performance of LX landrace at the designed growth conditions. Under both normal and stress conditions, significant differences in the expressions of a suite of secondary metabolism genes, particularly the genes from general phenylpropanoid pathway, were detected in LX comparing to William82 plants. Consistently, correlating with the transcript analysis, a set of corresponding secondary metabolites with profoundly different accumulations were also detected in LX plants. Further correlation analysis between metabolites and transcripts pointed to a MYB transcription factor likely sitting at the top of the regulation module, which is responsible for the LX agronomic traits. Our study provides the multilateral information of global regulatory mechanism of secondary metabolism on soybean drought resistance.