The p H plays a key role in the growth and colonization of plant pathogens as well as the onset and progression of the symptoms they cause within the host.Plants may quickly alter their apoplastic p H(pH_(apo))to prot...The p H plays a key role in the growth and colonization of plant pathogens as well as the onset and progression of the symptoms they cause within the host.Plants may quickly alter their apoplastic p H(pH_(apo))to protect themselves against infection.However,pathogens can also alter the p H of their ambient environment to promote their own growth.Citrus canker is a serious plant disease caused by Xanthomonas citri subsp.citri(Xcc).This Gram-negative aerobic rod is usually cultured in Luria-Bertani(LB)medium at p H 7.However,little is known about the changes in p H both in this medium as Xcc grows and in the leaf apoplast in response to Xcc infection and colonization.Moreover,the differences in leaf apoplast p H between Xcc-resistant and Xcc-susceptible citrus genotypes are also unknown.Here,Xcc grew well in liquid LB medium at initial p H6-8 and the pathogen altered the medium p H to 6.8±0.4.Xcc growth declined at p H 5 and was zero at p H 3,4,9,and 10.In susceptible sweet orange infected with Xcc inoculum,canker symptoms were inhibited at p H 3,4,and 10 but did not differ in the range of p H 5-9.As expected,canker symptoms were absent at all inoculum p H in the resistant Citron C-05.For both genotypes,Xcc only grew well in the leaves exposed to p H 5-8 inoculums.At four days post-inoculation(4 dpi),the foliar pH_(apo)of resistant Citron C-05 had rapidly declined from 5.6 to 4.4.At 2 dpi,the p Hapoof susceptible sweet orange had rapidly increased from 5.6 to 6.7,Xcc grew quickly,and canker symptoms appeared.Plasma membrane(PM)H^(+)-ATPase activation with fusicoccin(FC)acidified the apoplast and upregulated the pathogenesis-related genes(PRs)in the sweet orange leaves.Hence,Xcc colonization and canker development were inhibited.The results of this study revealed that apoplastic acidification is implicated in the resistance of Citron C-05 to Xcc infection and provided insight into the association between pH_(apo)regulation and resistance to bacterial pathogen invasion in plants.展开更多
基金supported by grants from the Provincial Special Project of the Research and Demonstration of High-Efficiency Breeding Technology for Citrus,China(Grant No.2024sfq02)Postgraduate Scientific Research Innovation Project of Hunan Province,China(Grant No.CX20210671).
文摘The p H plays a key role in the growth and colonization of plant pathogens as well as the onset and progression of the symptoms they cause within the host.Plants may quickly alter their apoplastic p H(pH_(apo))to protect themselves against infection.However,pathogens can also alter the p H of their ambient environment to promote their own growth.Citrus canker is a serious plant disease caused by Xanthomonas citri subsp.citri(Xcc).This Gram-negative aerobic rod is usually cultured in Luria-Bertani(LB)medium at p H 7.However,little is known about the changes in p H both in this medium as Xcc grows and in the leaf apoplast in response to Xcc infection and colonization.Moreover,the differences in leaf apoplast p H between Xcc-resistant and Xcc-susceptible citrus genotypes are also unknown.Here,Xcc grew well in liquid LB medium at initial p H6-8 and the pathogen altered the medium p H to 6.8±0.4.Xcc growth declined at p H 5 and was zero at p H 3,4,9,and 10.In susceptible sweet orange infected with Xcc inoculum,canker symptoms were inhibited at p H 3,4,and 10 but did not differ in the range of p H 5-9.As expected,canker symptoms were absent at all inoculum p H in the resistant Citron C-05.For both genotypes,Xcc only grew well in the leaves exposed to p H 5-8 inoculums.At four days post-inoculation(4 dpi),the foliar pH_(apo)of resistant Citron C-05 had rapidly declined from 5.6 to 4.4.At 2 dpi,the p Hapoof susceptible sweet orange had rapidly increased from 5.6 to 6.7,Xcc grew quickly,and canker symptoms appeared.Plasma membrane(PM)H^(+)-ATPase activation with fusicoccin(FC)acidified the apoplast and upregulated the pathogenesis-related genes(PRs)in the sweet orange leaves.Hence,Xcc colonization and canker development were inhibited.The results of this study revealed that apoplastic acidification is implicated in the resistance of Citron C-05 to Xcc infection and provided insight into the association between pH_(apo)regulation and resistance to bacterial pathogen invasion in plants.
