Details

Autor(en) / Beteiligte

• Khodadadi, Fatemeh
• Tohidfar, Masoud
• Vahdati, Kourosh
• Dandekar, Abhaya M.
• Leslie, Charles A.

Titel

Functional analysis of walnut polyphenol oxidase gene (JrPPO1) in transgenic tobacco plants and PPO induction in response to walnut bacterial blight

Ist Teil von

• Plant pathology, 2020-05, Vol.69 (4), p.756-764

Ort / Verlag

Oxford: Wiley Subscription Services, Inc

Erscheinungsjahr

2020

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Walnut (Juglans regia) is economically important for both its wood and nut nutritional value, but it is susceptible to diseases such as walnut bacterial blight, caused by Xanthomonas arboricola pv. juglandis (Xaj). Walnuts contain many phenolic compounds, providing a good model on which to study polyphenol oxidase (PPO). We inoculated the detached walnut fruits of cultivars Ford, Chandler, Franquette, Robert Livermore, and Payne with Xaj and measured the induction of PPO activity in infected sites and adjacent to infected sites. Compared to infected and uninfected sites, PPO activity was induced significantly in areas adjacent to infected sites in all cultivars except Ford. Ford and Franquette, presenting the lowest and highest PPO activity, showed the largest and smallest mean diameter spots in response to Xaj, respectively. Polyacrylamide gel electrophoresis confirmed monophenol oxidase activity of walnut PPO in the assessed tissues. Then, we revealed the antipathogenic potential of walnut PPO through Agrobacterium tumefaciens‐mediated walnut JrPPO1 gene transfer into tobacco (Nicotiana tabacum). Two transformed tobacco lines overexpressing the JrPPO1 gene were regenerated successfully and challenged with Pseudomonas syringae pv. tabaci. Transgenic lines showed significantly higher PPO activity and lower disease severity to the pathogen compared to the control. However, a significant difference in disease severity and PPO activity level was observed between the two transgenic lines. Our results demonstrate a potential defence‐related role of PPO in transgenic tobacco and its induction in areas adjacent to infection sites in walnut cultivars treated with Xaj. PPO activity increases in walnut fruit hulls infected with Xanthomonas arboricola pv. juglandis. Transgenic tobacco plants overexpressing the walnut PPO gene showed increased PPO activity and tolerance to Pseudomonas syringae pv. tabaci.