LhHSP90 Positively Regulates Tolerance to 5% PEG6000-induced Stress in Lily Cut Flower

Background Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that is widely distributed in both prokaryotes and eukaryotes and plays crucial roles in plant growth, development, and responses to environmental stresses. Results In this study, LhHSP90 was cloned from lily ( Lilium ‘ Manissa ’) and functionally characterized. Subcellular localization research revealed that LhHSP90 was predominantly localized in the nucleus. Expression profiling showed that LhHSP90 was highly expressed in petals and leaves, reached its highest transcript level at the full-bloom stage during the flower development, and was markedly induced by drought stress. Under 5% PEG-6000 treatment, transient silencing of LhHSP90 significantly shortened vase life, increased malondialdehyde (MDA) accumulation, and reduced the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Consistently, the transcript levels of antioxidant enzyme-related genes, including LhCu/ZnSOD , LhFeSOD , LhMnSOD , LhCAT , and LhPOD , were significantly decreased. In contrast, transient overexpression of LhHSP90 delayed petal browning and reduced relative electrolyte leakage. Furthermore, transgenic Arabidopsis plants expressing LhHSP90 exhibited longer primary roots than wild-type (WT) plants under 250 mM mannitol treatment. Following drought stress and subsequent rewatering, transgenic plants showed a significantly higher survival rate than WT plants and displayed markedly increased expression of the drought-responsive gene AtDR22 . Conclusions Collectively, these results indicate that Our findings provide new insights into the molecular mechanisms underlying drought tolerance in lilies and identify LhHSP90 as a potential target for the genetic improvement of stress resistance in cut lilies.