Combined effect of salt stress and Xanthomonas axonopodis pv citri on citrus (Citrus aurantifolia)

Shahran Ahmed Nayem; M Salahuddin M Chowdhury; Nazneen Sultana; Gazi Ziaul Haque Masum; Md Shahedur Rahman; Mohammad Abu Hena Mostofa Jamal

doi:10.1016/j.heliyon.2020.e03403

Combined effect of salt stress and Xanthomonas axonopodis pv citri on citrus (Citrus aurantifolia)

Heliyon. 2020 Feb 12;6(2):e03403. doi: 10.1016/j.heliyon.2020.e03403. eCollection 2020 Feb.

Authors

Shahran Ahmed Nayem^{1

2}, M Salahuddin M Chowdhury¹, Nazneen Sultana¹, Gazi Ziaul Haque Masum^{3

2}, Md Shahedur Rahman⁴, Mohammad Abu Hena Mostofa Jamal³

Affiliations

¹ Dept of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh.
² Department of Horticultural Science Technical University of Munich, Freising, Germany.
³ Dept. of Biotechnology and Genetic Engineering, Islamic University, Kushtia, Bangladesh.
⁴ Dept. of Genetic Engineering and Biotechnology, JUST, Jessore, Bangladesh.

Abstract

Xanthomonas axonopodis pv citri (Xac) and salt stress are two crucial hindrances to citrus production. The effect of continuous salt application and Xac infection in citrus has been investigated. Citrus plants were exposed to salt stress by irrigating with 50 mM, 100 mM, 150 mM, and 200 mM NaCl solution on weekly basis and challenged by Xac. Salt stress affected the defense response of Citrus plants to Xac and therefore lesion diameter and disease severity were gradually increased at higher salt concentration. Meanwhile, accumulation of Na⁺ and Cl^- in the leaves were also increased with the increase of salt concentration. Besides, physiological performance (PP) of plants was estimated based on the parameters such as net assimilation rate, chlorophyll content, stomatal conductance, transpiration rate and intercellular CO₂ concentration. The PP of sole Xac treated plants was gradually increased and maintained up to end of the experiment, whereas plants treated with Xac+50 mM and Xac+100 mM NaCl showed the highest PP up to 30 days after inoculation and then decreased. However, the PP of Xac+150 mM and Xac+200 mM NaCl treated plants gradually decreased till the end of experiment. Similarly, the PP of 200 mM NaCl treated plants declined continuously. Interestingly, the PP in 50 mM and 100 mM NaCl treated plants was higher initially and then decreased at 30 DAI to 40 DAI. This study revealed that citrus canker disease development was enhanced by salt stress. In addition, the physiological performance of the plants was enhanced by Xac and Xac + moderate salt stress but then demolished under severe salt stress.

Keywords: Agriculture; Chlorophyll content; Citrus canker; Intercellular CO2 concentration; Net assimilation rate; Plant biology; Salt stress; Stomatal conductance; Transpiration rate.