Abscisic acid induces differential expression of genes involved in wound-induced suberization in postharvest tomato fruit

Fruit wounding occurred at harvest and transportation requires rapid suberization as a major part of the healing process to prevent infection and desiccation. The focus of this work was to explore the mediation of abscisic acid(ABA) on woundinduced suberization and to determine expression profiles of specific genes involved in wound-induced suberization in tomato fruit. The measurements of weight loss and fruit firmness suggested wound-induced suberization started at 2 d after wounding. The suberization process with the accumulation of suberin polyphenolics(SPP) and polyaliphatics(SPA) observed through autofluorescence microscopy and Sudan IV staining was accelerated by ABA. Expressions of SlPAL5 and Sl4 CL involved in the synthesis of SPP reached the highest at 4 and 8 d after wounding following ABA application, respectively. Associated with SPA biosynthesis, SlLACS1 and SlLACS2 showed the most abundant transcripts at 8 and 6 d in ABA group, respectively. Transcript levels including SlKCSs, SlCYP86 B1, SlFAR3, and Sl GPATs were up-regulated at 2 d after wounding by ABA. Activities of polyphenol oxidase and lipoxygenase were also enhanced during wound-induced suberization following ABA application. The results in this study proved that ABA accelerated the wound-induced suberization progress by increasing the transcript levels of relevant genes in postharvest tomato fruit.

Importers Drive Leaf-to-Leaf Jasmonic Acid Transmission in Wound-Induced Systemic Immunity

The transmission of mobile wound signals along the phloem pathway is essential to the activation of wound-induced systemic response/resistance,which requires an upsurge of jasmonic acid(JA)in the distal undamaged leaves.Among these mobile signals,the electrical signal mediated by the glutamate-dependent activation of several clade three GLUTAMATE RECEPTOR-LIKE(GLR3)proteins is involved in the stimulation of JA production in distal leaves.However,whether JA acts as a mobile wound signal and,if so,how it is transmitted and interacts with the electrical signal remain unclear.Here,we show that JA was translocated from the local to distal leaves in Arabidopsis,and this process was predominantly regulated by two phloem-expressed and plasma membrane-localized jasmonate transporters,AtJAT3 and AtJAT4.In addition to the cooperation between AtJAT3/4 and GLR3.3 in the regulation of long-distance JA translocation,our findings indicate that importer-mediated cell-cell JA transport is important for driving the loading and translocation of JA in the phloem pathway in a self-propagating manner.

Introduction of pokeweed antiviral protein cDNA into Brassica napus and acquisition of transgenic plants resistant to viruses

Using cotyledonary petioles as explants, the PAP cDNA controlled by wound-in-ducible promoter has been introduced into Brassica napus by coculture with Agrobacterium tumefaciens and laser microbeam puncture respectively. Regenerated plants resistant to gen-tamycin have been selected out. PCR amplification and Southern blotting analysis indicated that PAP cDNA together with wound-inducible promoter had been integrated into Brassica genome with transformation frequencies of 2.0% and 1.7% for two transformation methods respectively. The test of virus challenge showed that these transgenic Brassica plants were resistant in different degrees to mechanically inoculated TuMV.