Plant growth and development are closely related to the environment, and high-temperature stress is an important environmental factor that affects these processes. WRKY transcription factors (TFs) play important roles in plant responses to high-temperature stress. WRKY TFs can bind to the W-box cis-acting elements of target gene promoters, thereby regulating the expression of multiple types of target genes and participating in multiple signaling pathways in plants. A number of studies have shown the important biological functions and working mechanisms of WRKY TFs in plant responses to high temperature. However, there are few reviews that summarize the research progress on this topic. To fully understand the role of WRKY TFs in the response to high temperature, this paper reviews the structure and regulatory mechanism of WRKY TFs, as well as the related signaling pathways that regulate plant growth under high-temperature stress, which have been described in recent years, and this paper provides references for the further exploration of the molecular mechanisms underlying plant tolerance to high temperature.

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Cut flower quality is severely restrained by stem bending due to low stem strength. Melatonin has been shown to function in many aspects of plant growth and development, yet whether it can enhance stem strength and the corresponding underlying mechanisms remain unclear. We investigated the role of melatonin in the enhancement of herbaceous peony (Paeonia lactiflora Pall.) stem strength by applying exogenous melatonin and changing endogenous melatonin biosynthesis. Endogenous melatonin level positively correlated with the lignin content and stem strength in various P. lactiflora cultivars. Supplementation with exogenous melatonin significantly enhanced stem strength by increasing lignin content and the S/G lignin compositional ratio, upregulating lignin biosynthetic gene expression. Moreover, overexpression of tryptophan decarboxylase gene (TDC) responsible for the first committed step of melatonin biosynthesis in tobacco significantly increased endogenous melatonin, which further increased the S/G ratio and stem strength. Whereas silencing PlTDC in P. lactiflora decreased endogenous melatonin, the S/G ratio and stem strength. Finally, manipulating the expression of caffeic acid O-methyltransferase gene (COMT1), which is involved in both melatonin and lignin biosynthesis, showed even greater effects on melatonin, the S/G ratio and stem strength. Our results suggested that melatonin had a positive regulatory effect on P. lactiflora stem strength.

6001 Background: In China, secondary cytoreductive surgery (SCR) has been standard of care in some high volume cancer centers for ovarian cancer (OC) and most pts prefer surgery over the past two decades. Although GOG213 showed no OS benefit, the debate on selected pts and the conflict with certain local clinical care is still open. Methods: Pts with 1st relapsed OC after 6m+ platinum-free interval (PFI) were eligible if predicted to be a potential R0 by iMODEL score combined with PET-CT image and were randomized to SCR followed by chemotherapy (surgery arm) vs 2nd line chemotherapy alone (no surgery arm). Co-primary endpoint is PFS and OS. The 2nd endpoint is accumulated treatment-free survival (TFSa), which was defined as the overall survival time minus the time of surgery and chemotherapy after randomization. We report analysis of PFS and interim analysis of TFSa. Results: 357 pts were randomized 2012-2019. 6.3% of 175 pts were operated in no surgery arm and cross-over rate was 36.9% in 2nd+ relapsed pts of no surgery arm. 97% and 96% of pts received a platinum-containing 2nd line therapy. Complete resection (R0) rate was 76.7% in overall and 61.1% in pts with iMODEL> 4.7. 60 d mortality rates were 0 % in both surgery and no surgery arm. Postoperative 30 d complication rate with ≥ grade 3 was 5.2%. The median follow-up was 36.0 m. Median PFS was 17.4 m and 11.9 m in surgery and no surgery arm, respectively (HR 0.58, 95% CI 0.45-0.74, p < 0.001). Median time to start of first subsequent therapy (TFST) was 18.1 m vs 13.6 m in favor of the surgery arm (HR 0.59, 95%CI 0.46-0.76). 1.1% and 10.1% of pts underwent Bevacizumab and PARPi maintenance in the 2nd line therapy. The OS and TFSa was immatured. The median TFSa was unreached and 39.5 m in R0 subgroup and no surgery arm, respectively (HR0.59, 95%CI 0.38-0.91). TFSa in surgery arm showed a better long-term survival than that in no surgery group (restricted mean survival time from 60 to 72m: 6.2m vs 4.2m). Conclusions: SCR in selected pts resulted in a dramatically significant extension of PFS. The interim analysis of TFSa indicate that SCR might contribute to long-term survival.