Transcriptomic Profiling Reveals Transcriptional Factors and Their Regulations for the Improved Drought Tolerance in Ipt-Transformed Creeping Bentgrass.

Our previous research showed that creeping bentgrass cultivar “Penncross” transformed with SAG12-ipt showed improved drought tolerance. Transcriptomic profiling was conducted in both “Penncross” and ipt-transgenic plant under drought stress, in order to find out the regulatory mechanism related to drought stress tolerance. Transcription factors (TFs) and their target genes, receptor kinases, protein modification and degradation genes that showed differential expression levels in ipt-transgenic plant under drought stress were annotated and obtained in various online databases. In total, there were 65 and 62 TFs that showed significantly increased and decreased expression levels in ipt-transgenic under drought stress, compared with “Penncross”. Among them, 18 TFs were able to find their target genes also differentially expressed. In addition, we also found 23 increased and 18 decreased receptor kinases, 34 increased and 18 decreased protein modification genes, 24 increased and 28 decreased protein degradation genes that showed significant differences in ipt-transgenic. Most importantly, we revealed an overview network of improved drought tolerance, nested with central hubs of zinc finger helix loop helix TF (bHLH148) and WRKY28, 53, 71 and 74, increased jasmonate signaling and decreased abscisic acid signaling regulations, and more efficient MAPKKK15, 17 mediated protein modification and degradation, in ipt-transgenic plant under drought. These findings pave the way for future research of the individual pathways as well as key regulators, with the aim to understand the mechanisms of cytokinin-mediated drought tolerance in creeping bentgrass.