![]() Moreover, Xa4 complements Xa7 resistance with no Xoo spread in planta beyond the symptomatic area under both temperature regimes in IRBB67. The pyramided line IRBB67 showed no differences in lesion length between both temperature regimes, demonstrating that non-effectiveness of Xa4 at high temperature did not affect IRBB67 resistance. Influence of high temperature on both R genes ( Xa4+Xa7) combined in IRBB67 was analyzed under growth chamber conditions and transcriptomic analysis performed. Recently, a reduced resistance in rice IRBB4 carrying Xa4, but an increase in resistance in IRBB7 carrying Xa7 resistance by increasing temperature has been reported. Increasing temperature often turns into inhibition of host plant defense to pathogens. In times of climate change, increasing temperatures are observed and further acceleration is expected worldwide. oryzae ( Xoo) implies substantial yield loss to rice. ananatis and Xoo, respectively need to be determined in the future.Ĭausal Agent Crop Type Field crops Pathogen detection Prokaryotes Subject Areas cereals and grains.Rice bacterial blight (BB) caused by Xanthomonas oryzae pv. Further, the differences of occurrence, spread and control between two rice bacterial leaf blight diseases caused by P. ananatis, instead of Xoo as traditionally assumed. This study raises the alarm that the emerging rice bacterial leaf blight in southeast China might be caused by a new pathogen P. ananatis as the causative agent of rice leaf blight in southeast China. Nevertheless, to the best of our knowledge, this is the first report of P. 2010) and induce leaf blight as a companion of Enterobacter asburiae in Sichuan province, China (Xue et al. ananatis has been reported to cause grain discoloration in Hangzhou, China (Yan et al. ananatis was re-isolated in the inoculated rice plants, fulfilling Koch's postulates. In contrast, the control plants remained healthy and symptomless. At about 14 DAI, blight was shown with similar symptoms to those samples collected from the rice field of Zhejiang and Jiangxi provinces (Fig. The clipped leaves displayed water-soaked lesions at 3 to 5 days after inoculation (DAI) then the lesion spread downward and turned light brown. Zhongzao39) at the late booting stage using clipping method. For pathogenicity tests, bacterial suspension at 108 CFU/mL was inoculated into flag leaves of rice (cv. Based on the above morphological, physiological, biochemical and molecular data, the isolates are identified as P. Phylogenetic analysis of gyrB, leuS and rpoB concatenated sequences indicated that the 6 isolates were clustered in a stable branch with P. ![]() 2008) and GenBank accession numbers of gene sequences from the 6 isolates are listed in Table S1 and Table S2. ananatis identity of these isolates, fragments of three housekeeping genes including gyrB, leuS and rpoB from the 6 isolates were amplified and sequenced, which showed highest homology to LMG 2665T with a sequence similarity of 95%-100% (Table S3). 16S rRNA gene sequence analysis from the 6 isolates (FY43, JH31, JH99, TZ20, TZ39 and TZ68) revealed that the amplified fragments shared 98% similarity with Pantoea ananatis type strain LMG 2665T (GenBank JFZU01) (Table S3). The cells were all gram-negative and rod-shaped with three to six peritrichous flagella positive for catalase, indole, glucose fermentation and citrate utilization, while negative for oxidase, alkaline, phenylalanine deaminase, urease, and nitrate reductase reactions. ![]() All isolates showed circular, smooth-margined, yellow colonies when cultured on peptone sugar agar (PSA) medium for 24h at 28℃. 63 isolates were obtained from the collected diseased leaves as previously described (Hou et al. ![]() oryzae (Xoo), the pathogen of rice bacterial blight. The disease symptoms were assumed to be caused by Xanthomonas oryzae pv. Initially, water-soaked, linear, light brown lesions emerged in the upper blades of the leaves, and then spread down to leaf margins, which ultimately caused leaf curling and blight during the booting-harvest stage (Fig. ![]() In autumn 2020, leaf blight was observed on rice (Oryza sativa L., variety Zhongzao39, Yongyou9, Yongyou12, Yongyou15, Yongyou18, Yongyou1540, Zhongzheyou8, Jiafengyou2, Xiangliangyou900 and Jiyou351) in the fields of 17 towns in Zhejiang and Jiangxi Provinces, China. ![]()
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