StJAZ1-like mediated root architecture plays critical roles in drought susceptibility in potato

Unlike other major crops, the potato root system is formed by adventitious roots in tuber-grown plants, and considered inefficient. Root architectural traits define plant performance and yield, particularly under the restricted water level. The phytohormones are the major players in root development. But the phytohormones which regulate adventitious root formation in potato plant and consequently contribute to drought tolerance, are not well studied. Here, we have now found that StJAZ1-like, a suppressor in jasmonic acid (JA) signaling, enhances drought susceptibility by attenuating adventitious root formation in potato. The StJAZ1-like-overexpressing (StJAZ1-like ox) potato plants were more sensitive to drought compared to wild type (WT) plants. Grafting experiments showed that the increased drought susceptibility was due to the attenuated root architecture. In addition, overexpression of StJAZ1-like caused a decrease in relative leaf water content in potato plants under drought stress. Under the drought stress, malondialdehyde (MDA) content was significantly higher, while antioxidant enzymes like superoxide dismutase (SOD) and peroxidase (POD) activities were significantly less in StJAZ1-like ox plants. Further, transcriptome profiling analysis of the root tips revealed that the expression levels of three tandem-arranged small auxin upregulated RNA (SAUR) genes were significantly upregulated in StJAZ1-like ox plants. StJAZ1-like ox plants exhibited an enhanced auxin response, suggesting StJAZ1-like modulates auxin responses. Taken together, our results suggested StJAZ1-like plays critical roles in root architecture and drought susceptibility in potato.