Isolation and functional analysis of drought related PobZIP4 transcription factor in Paeonia ostii

Drought, as a natural disaster of force majeure, significantly disrupts the physiological balance of plants and crop yields. The basic leucine zipper (bZIP) transcription factors assume the pivotal role of paramount regulators in orchestrating drought response. In this study, a bZIP transcription factor PobZIP4 was isolated on the base of Paeonia ostii transcriptome, and its function in response to drought stress was verified. PobZIP4 had a 579 bp open reading frame, encoded 192 amino acids, and existed in a conserved structural domain typical of bZIP, and was highly expressed when P. ostii was stressed by drought. Moreover, the subcellular localization of PobZIP4 was observed with fluorescent protein labeling method and it was found that PobZIP4 localized in the Nicotiana benthamiana epidermal cell nucleus. Then, we silenced PobZIP4 in P. ostii using virus-induced gene silencing technology, and found that PobZIP4-silenced plants showed significantly less tolerant to drought stress than the negative control. The accumulation of reactive oxygen species was found to be heightened, while the photosynthetic capacity, proline content, and protective enzyme activities exhibited a significant decline upon silencing PobZIP4, which unequivocally demonstrated that PobZIP4 amplifies the drought tolerance of P. ostii. This study highlighted the positive role of PobZIP4 in mitigating drought stress in P. ostii, thereby establishing a molecular basis for enhancing the drought tolerance of P. ostii.