The Interaction Between StCDPK14 and StRbohB Contributes to Benzo-(1, 2, 3)-Thiadiazole-7-Carbothioic Acid S-Methyl Ester-Induced Wound Healing of Potato Tubers by Regulating Reactive Oxygen Species Generation

Li Ma,Ying-Yue Ren,Huai-Jun Si,Jiang-Wei Yang,Yang Bi,Hong Jiang,Dov Prusky,Yong-Cai Li

doi:10.3389/fpls.2021.737524

Abstract

Reactive oxygen species (ROS) production is essential for both physiological processes and environmental stress in diverse plants. Previous studies have found that benzo-(1, 2, 3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH)-inducible ROS were associated with wound healing of potato tubers. Calcium-dependent protein kinases (CDPKs), the important calcium receptors, are known to play a crucial part in plant development and adaptation to abiotic stresses. However, whether CDPK-mediated ROS generation induced by BTH is involved in wound healing is elusive. In this study, we measured Solanum tuberosum CDPKs (StCDPKs) expression using real-time PCR, and it was found that the transcriptional levels of StCDPKs from BTH-treated tissues were significantly induced, among which StCDPK14 presented the most increased level. Subcellular localization results showed that StCDPK14 is located in the nucleus and membrane. The transgenic potato plants and tubers were developed using interference-expression of StCDPK14 by Agrobacterium tumefaciens–mediated transformation. The St respiratory burst oxidase homologs (StRbohs) expression showed a remarkable decrease in StCDPK14 transgenic tubers, notably, H2O2 content and suberin deposition were also significantly declined. To confirm the relationship between StCDPK14 and StRbohB, yeast-two-hybrid and bimolecular fluorescence complementation were used to examine the interaction, and it was shown that StCDPK14 interacted with the specific Ca2 + -binding motif (helix-loop-helix, called EF-hand) of StRbohB N-terminus. The above results unraveled that StCDPK14 functions in ROS generation via interacting with StRbohB during wound healing of potato tubers.

Highlights

Wound healing is a typical characteristic of harvested potato tubers, which protects against pathogen infection and prevents water evaporation (Lulai et al, 2016)
The transmission electron microscope (TEM) observation showed that Ca2+ precipitate particles in control and BTH-treated healing tissues distributed in large quantity in cytoplasm, and occasionally in cellular Ca2+ sink, such as mitochondria, endoplasmic reticulum, vacuoles, and plasmids
Ca2+ signal originates through appropriate environmental stresses, which is transferred into the nucleus where the related genes could involve in transcription activity (Swarbreck et al, 2013)

Summary

Introduction

Wound healing is a typical characteristic of harvested potato tubers, which protects against pathogen infection and prevents water evaporation (Lulai et al, 2016). Our previous study indicated benzo(1, 2, 3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), an analog of salicylic acid (SA) and the first artificially synthesized and commercialized elicitor registered as Bion R or Actigard R , stimulates defense responses via reactive oxygen species (ROS) production in diverse plants and promotes the wound healing of potato tubers by accelerating deposition of suberin and lignin at wound sites (Jiang et al, 2019). Further research has demonstrated the elicited wound healing of potato tubers by BTH involves in ROS metabolism via an increase of the respiratory burst oxidase homolog (Rboh) activity and transcriptional levels, leading to the enhancement of ROS (Jiang et al, 2020). There are several pathways to produce necessary ROS for wound healing of potato tubers; the Rboh is a major one (Razem and Bernards, 2003). Evidence demonstrated that the wound-induced oxidative burst of superoxide mediated by StRbohA promotes the wound healing of potato tubers (Kumar et al, 2007)

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Results

Conclusion