High-CO₂/Hypoxia-Responsive Transcription Factors DkERF24 and DkWRKY1 Interact and Activate DkPDC2 Promoter

Abstract

Identification and functional characterization of hypoxia-responsive transcription factors is important for understanding plant responses to natural anaerobic environments and during storage and transport of fresh horticultural products. In this study, yeast one-hybrid library screening using the persimmon (Diospyros kaki) pyruvate decarboxylase (DkPDC2) promoter identified three ethylene response factor (ERF) genes (DkERF23/DkERF24/DkERF25) and four WRKY transcription factor genes (DkWRKY/ DdkWRKY5/DkWRKY6/DkWRKY7) that were differentially expressed in response to high CO 2 (95%, with 4% N 2 and 1% oxygen) and high N 2 (99% N 2 and 1% oxygen). Yeast one-hybrid assays and electrophoretic mobility shift assays indicated that DkERF23, DkERF24, DkERF25, DkWRKY6, and DkWRKY7 could directly bind to the DkPDC2 promoter. Dual-luciferase assays confirmed that these transcription factors were capable of transactivating the DkPDC2 promoter. DkERF24 and DkWRKY1 in combination synergistically transactivated the DkPDC2 promoter, and yeast two-hybrid and bimolecular fluorescence complementation assays confirmed protein-protein interaction between DkERF24 and DkWRKY1. Transient overexpression of DkERF24 and DkWRKY1 separately and in combination in persimmon fruit discs was effective in maintaining insolubilization of tannins, concomitantly with the accumulation of DkPDC2 transcripts. Studies with Arabidopsis (Arabidopsis thaliana) homologs AtERF1 and AtWRKY53 indicated that similar protein-protein interactions and synergistic regulatory effects also occur with the DkPDC2 promoter. We propose that an ERF and WRKY transcription factor complex contributes to responses to hypoxia in both persimmon fruit and Arabidopsis, and the possibility that this is a general plant response requires further investigation.

Primary Metabolism in Fresh Fruits During Storage

“…This is the case of low oxygen and high carbon dioxide postharvest stress physiology studies. Recent reports describe the role of specific transcription factors (TFs) such as ethylene-responsive factors (ERFs), in synergy with WRKY and MYB elements, in controlling the expression of PDC gene promoter in persimmons under high carbon dioxide/ hypoxia (Zhu et al, 2018;Zhu et al, 2019). Specific and multiple TFs of different clades/classes and a TF regulatory network are involved in the responses to such storage conditions that induce marked changes of primary metabolism gene expression.…”

C2H2-Type Zinc Finger Proteins (DkZF1/2) Synergistically Control Persimmon Fruit Deastringency

“…The mechanisms of AHCA [6] were investigated long-term, due to its importance for the persimmon industry and because it is the ideal model for fruit hypoxia research. In recent years, studies have moved beyond physiological and biochemical analyses [16] to molecular aspects [6,22], with characterization of a few key TFs, such as DkERF9/10/19 [6], DkMYB6/10 [22], and DkWRKY1 [23]. However, the involvement of DkZFs on deastringency regulation remain unclear.…”

“…Due to its economic importance and the dramatic physiological changes, the regulatory mechanisms of AHCA on persimmon fruit deastringency were extensively investigated, especially on the transcription factors (TFs) and their regulatory mechanisms. Among them, some TFs (DkERF9/10/19) showed direct regulation of target genes ( DkADH/DkPDC ) [21], while other TFs constituted networks, such as transcriptional cascades [22] or TF complexes [23]. In addition to these dominant TFs, other TFs showed responsive expression patterns and limited transactivations, such as DkNAC7/16 [21,24,25].…”

Transcriptome co-expression network analysis identifies key genes and regulators of ripening kiwifruit ester biosynthesis

“…At present, research on the transcriptional regulatory mechanism of fruit aroma production mainly concentrate on terpenes, including citrus CitAP2.10 for (+)-valencene and CitERF71 for E-geraniol, and kiwifruit AaNAC2/3/4 for monoterpene biosynthesis [16][17][18]. In persimmon fruit, the ERFs could regulate the ADH promoter and might be key components in persimmon fruit astringency removal [19]. In kiwifruit, AcNAC5 increased significantly in response to propylene and showed correlation with aroma volatile production patterns, suggesting its potential role in the regulation of AcAAT and aroma volatile biosynthesis during ripening [3]; However, such findings only hint at the potential of TFs in ester related pathway regulation, and role of these ERFs and other TFs on esters biosynthesis remains unclear.…”