scholarly journals Systematic Analysis and Functional Validation of Citrus Pectin Acetylesterases (CsPAEs) Reveals that CsPAE2 Negatively Regulates Citrus Bacterial Canker Development

2020 ◽  
Vol 21 (24) ◽  
pp. 9429
Author(s):  
Qiang Li ◽  
Jia Fu ◽  
Xiujuan Qin ◽  
Wen Yang ◽  
Jingjing Qi ◽  
...  
Keyword(s):  
Susceptible Variety ◽  
Resistant Variety ◽  
Potential Candidate ◽  
Bacterial Canker ◽  
Citrus Pectin ◽  
Systematic Analysis ◽  
Canker Disease ◽  
Potential Candidate Gene ◽  
Citrus Bacterial Canker ◽  
Canker Development

The present study was designed to serve as a comprehensive analysis of Citrus sinensis (C. sinensis) pectin acetylesterases (CsPAEs), and to assess the roles of these PAEs involved in the development of citrus bacterial canker (CBC) caused by Xanthomonas citri subsp. citri (Xcc) infection. A total of six CsPAEs were identified in the genome of C. sinensis, with these genes being unevenly distributed across chromosomes 3, 6, and 9, and the unassembled scaffolds. A subset of CsPAEs were found to be involved in responses to Xcc infection. In particular, CsPAE2 was identified to be associated with such infections, as it was upregulated in CBC-susceptible variety Wanjincheng and inversely in CBC-resistant variety Calamondin. Transgenic citrus plants overexpressing CsPAE2 were found to be more susceptible to CBC, whereas the silencing of this gene was sufficient to confer CBC resistance. Together, these findings provide evolutionary insights into and functional information about the CsPAE family. This study also suggests that CsPAE2 is a potential candidate gene that negatively contributes to bacterial canker disease and can be used to breed CBC-resistant citrus plants.

scholarly journals CsPrx25, a class III peroxidase in Citrus sinensis, confers resistance to citrus bacterial canker through the maintenance of ROS homeostasis and cell wall lignification

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Qiang Li ◽  
Xiujuan Qin ◽  
Jingjing Qi ◽  
Wanfu Dou ◽  
Christophe Dunand ◽  
...  
Keyword(s):  
Cell Wall ◽  
Susceptible Variety ◽  
Resistant Variety ◽  
Bacterial Canker ◽  
Class Iii ◽  
Ros Homeostasis ◽  
Citrus Production ◽  
Citrus Bacterial Canker ◽  
Apoplastic Barrier

AbstractCitrus bacterial canker (CBC) results from Xanthomonas citri subsp. citri (Xcc) infection and poses a grave threat to citrus production. Class III peroxidases (CIII Prxs) are key proteins to the environmental adaptation of citrus plants to a range of exogenous pathogens, but the role of CIII Prxs during plant resistance to CBC is poorly defined. Herein, we explored the role of CsPrx25 and its contribution to plant defenses in molecular detail. Based on the expression analysis, CsPrx25 was identified as an apoplast-localized protein that is differentially regulated by Xcc infection, salicylic acid, and methyl jasmone acid in the CBC-susceptible variety Wanjincheng (C. sinensis) and the CBC-resistant variety Calamondin (C. madurensis). Transgenic Wanjincheng plants overexpressing CsPrx25 were generated, and these transgenic plants exhibited significantly increased CBC resistance compared with the WT plants. In addition, the CsPrx25-overexpressing plants displayed altered reactive oxygen species (ROS) homeostasis accompanied by enhanced H2O2 levels, which led to stronger hypersensitivity responses during Xcc infection. Moreover, the overexpression of CsPrx25 enhanced lignification as an apoplastic barrier for Xcc infection. Taken together, the results highlight how CsPrx25-mediated ROS homeostasis reconstruction and cell wall lignification can enhance the resistance of sweet orange to CBC.

scholarly journals Adult Citrus Leafminers (Phyllocnistis citrella) Are Not Efficient Vectors for Xanthomonas axonopodis pv. citri

Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 590-594 ◽  
Author(s):  
J. Belasque ◽  
A. L. Parra-Pedrazzoli ◽  
J. Rodrigues Neto ◽  
P. T. Yamamoto ◽  
M. C. M. Chagas ◽  
...  
Keyword(s):  
Citrus Canker ◽  
Free Access ◽  
Bacterial Canker ◽  
Phyllocnistis Citrella ◽  
Canker Disease ◽  
Xanthomonas Axonopodis ◽  
Rangpur Lime ◽  
Citrus Leafminer ◽  
Citrus Bacterial Canker ◽  
Experimental Trials

Interest in the interaction between the citrus leafminer (Phyllocnistis citrella) and citrus bacterial canker, caused by Xanthomonas axonopodis pv. citri, has increased as a greater incidence and severity of canker-diseased plants was observed in groves infested with the citrus leafminer. To determine whether adults of the citrus leafminer could act as vectors of citrus canker, we investigated two potential mechanisms for direct spread by leafminer adults using experimental microcosms. First, adult leafminers were raised on canker-infected foliage and were allowed to mate and lay eggs on healthy plants. These plants then were observed for development of citrus canker symptoms. In a second set of experiments, adults raised on healthy plants were given free access to canker-diseased plants during the period in which they mated and laid eggs on healthy plants. In all, 3,119 mines were produced by developing larvae on a total of 2,384 leaves examined for citrus canker symptoms. No symptoms of citrus bacterial canker disease were observed on any of the healthy test plants in 37 independent experimental trials conducted to test these two potential mechanisms of spread of citrus canker, and the pathogen was not recovered from insects exposed to symptomatic Rangpur lime plants. The upper limit on the rate of transmission was estimated to be less than 0.2% per oviposition event based on the binomial probability distribution. However, when adult P. citrella insects were artificially contaminated with high levels of X. axonopodis pv. citri, transmission to Rangpur lime plants with the induction of citrus canker was observed. This suggests that the ability of P. citrella to transmit X. axonopodis pv. citri is limited by the rate at which it can acquire inoculum from infected plants. The results support the conclusion that adult citrus leafminers are not efficient vectors for citrus canker bacteria, and the disease is unlikely to be spread this way.

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