Cold plasma seed treatment improves chilling resistance of tomato plants through hydrogen peroxide and abscisic acid signaling pathway

Abstract

How to develop a simple and economic approach to improve plant cold stress tolerance is an important scientific problem. With the hope that we explored the effect and metabolism of cold plasma (CP) seed treatment on the chilling tolerance in tomato plants. 75 W CP seed treatment showed the best mitigative effect on cold-induced injury of tomato seedlings, as evidenced by the higher maximum photochemical efficiency of PSII (Fv/Fm), lower ion leakage and chilling injury index. Moreover, the results showed that CP-induced chilling tolerance was related to the hydrogen peroxide (H2O2) mediated by respiratory burst oxidase homologue 1 (RBOH1), which was proved by the decrease low temperature tolerance observed in RBOH1 silence or chemical scavenging of H2O2 seedlings. Furthermore, RBOH1-mediated H2O2 acted as the downstream signaling of CP treatment to enhance the levels of abscisic acid (ABA) by increasing the transcript of 9-cis-epoxycarotenoid dioxygenase 1 (NCED1). Mutation of NCED1 completely abolished CP-induced cold resistance. Genetic evidence showed that H2O2 and ABA were positive regulators of cold stress tolerance. Thus, CP-induced H2O2 and ABA cascade signal up-regulated the regulatory genes (ICE1 and CBF1) of cold acclimation, which increased the osmotic adjustment substances (proline and soluble sugar) accumulation and antioxidant enzymes (SOD, APX and CAT) activities. Our results indicate that H2O2 and ABA signals are involved in conferring cold stress tolerance induced by CP seed treatment in tomato plants.