Xueyuan Han,Linchun Mao,Wenjing Lu,Xiaopeng Wei,Tiejin Ying,Zisheng Luo
Wound-induced suberization is an essentially protective healing process for wounded fruit to reduce water loss and microbial infection. It has been demonstrated that abscisic acid (ABA) could promote wound suberization, but the molecular mechanism of ABA regulation remains little known. In this study, the transcript level of Achn030011 (designated as AchnKCS), coding a β-ketoacyl-coenzyme A synthase (KCS) involved in suberin biosynthesis, was found to be significantly upregulated by ABA in wounded kiwifruit. A bZIP transcription factor (Achn270881), a possible downstream transcription factor in the ABA signaling pathway, was screened and designated as AchnbZIP12 according to its homology with related Arabidopsis transcription factors. A yeast one-hybrid assay demonstrated that AchnbZIP12 could interact with the AchnKCS promoter. Furthermore, significant trans-activation of AchnbZIP12 on AchnKCS was verified. The transcript level of AchnbZIP12 was also upregulated upon treatment with ABA. These results imply that AchnbZIP12 acts as a positive regulator in ABA-mediated AchnKCS transcription during wound suberization of kiwifruit.
The development of wound periderm is vital to prevent water vapor loss and pathogen invasion in wounded fruit. The effect of abscisic acid (ABA) on wound-healing in harvested tomato fruit was evaluated in this study. Wounded tomato fruit were treated with ABA or fluridone (FLD, an inhibitor of ABA biosynthesis), respectively, and allowed to wound-heal at 20 °C in darkness for 4 days. Weight loss of tomato fruit reflected the intuitionistic effects of different treatments during wound-healing. Autofluorescence and histochemical staining demonstrated the development of suberized wound periderm in harvested tomato fruit at 3–4 day after wounding. Alkanoic acids, n -alkanes, unsaturated fatty acids and pentacosane represented the major components in the suberin. ABA-treated fruit showed enhanced autofluorescence, histochemical intensity and suberin deposition along with increased activities of phenylalanine ammonia-lyase (PAL) and peroxidase (POD). FLD treatment, however, alleviated the features of suberization and enzyme activities during wound-healing. The results suggest that ABA is involved in the stimulation of wound-induced suberization in harvested tomato fruit.
Wound-induced suberization is an essentially protective healing process for fruit to reduce water loss and avoid infecting. However, cognate mechanisms that regulate this process are little known. To expand our knowledge of suberization induced by wounding, a wound-healing investigation together with metabolite profiling study was conducted in postharvest kiwifruit ( Actinidia deliciosa ). The development of suberization in wounded fruit was demonstrated by autofluorescence observation and toluidine blue staining at 1–4 day (d) after wounding. Activities of phenylalanine ammonia-lyase (PAL), cinnamyl-alcohol dehydrogenase (CAD) and peroxidase (POD) in wound-healing tissue were enhanced by abscisic acid (ABA). The constituent analysis of suberin including polyphenolics (SPP) and polyaliphatics (SPA) proved that exogenous ABA increased the content levels of total phenols, total flavonoids and alkanes, alkenes, alcohols, alkane acids, olefine acids, esters, glycerides and vitamin E in wound-healing tissue. Results suggested that ABA stimulated suberization through the activation of PAL, CAD and POD to accelerate wound-healing of wounded kiwifruit.
Han Xueyuan,Wei Xiaopeng,Lu Wenjing,Wu Qiong,Mao Linchun,Luo Zisheng
Background Our previous study has demonstrated that the transcription of AchnKCS involved in suberin biosynthesis was up-regulated by exogenous abscisic acid (ABA) during the wound suberization of kiwifruit, but the regulatory mechanism has not been fully elucidated. Results Through subcellular localization analysis in this work, AchnbZIP29 and AchnMYB70 transcription factors were observed to be localized in the nucleus. Yeast one-hybrid and dual-luciferase assay proved the transcriptional activation of AchnMYB70 and transcriptional suppression of AchnbZIP29 on AchnKCS promoter. Furthermore, the transcription level of AchnMYB70 was enhanced by ABA during wound suberization of kiwifruit, but AchnbZIP29 transcription was reduced by ABA. Conclusions Therefore, it was believed that ABA enhanced the transcriptional activation of AchnMYB70 on AchnKCS by increasing AchnMYB70 expression. On the contrary, ABA relieved the inhibitory effect of AchnbZIP29 on transcription of AchnKCS by inhibiting AchnbZIP29 expression. These results gave further insight into the molecular regulatory network of ABA in wound suberization of kiwifruit.
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