Dai Zhang

Potato late blight is an important disease in potato production, which causes serious damage. Salicylic acid (SA) is a plant hormone involved in the regulation of potato ( Solanum tuberosum ) resistance to Phytophthora infestans . In this study, it was found that exogenous methyl salicylate (MeSA) treatment could significantly enhance the resistance of potato to P. infestans . RNA‐seq results confirmed that SA was important for potato resistance to P. infestans . Salicylic acid binding protein 2 (SABP2) is a member of α/β hydrolase family, which can convert MeSA into SA to regulate the steady state of SA in plants. StSABP2 protein was obtained through prokaryotic expression, and enzymatic analysis in vitro confirmed that StSABP2 could transform MeSA into SA. In order to explore the function of StSABP2 in the process of plant resistance to P. infestans , we carried out virus‐mediated gene silencing of StSABP2 in potato and transiently expressed StSABP2 in tobacco. The results showed that StSABP2 positively regulated plant resistance to P. infestans , and this process was achieved by mediating the transcription of SA signal and defence‐related genes. Then we screened for the upstream regulator of StSABP2 . The results of double luciferase and yeast one‐hybrid analysis showed that StNAC2 could activate the transcription of StSABP2 . The StNAC2‐StSABP2 module regulated potato resistance to P. infestans by positively mediating the SA pathway. This study provides a new idea for improving host resistance to potato late blight by regulating the SA signal in potato and provides germplasm resources for potato resistance breeding.

Species belonging to the genus Erwinia cause diseases in many economically important plants (Mansfield et al. 2012). In May 2021, celery plants (Apium graveolens var. dulce) showing soft rot sympto...

In July 2020, potato plants (cv. Xisen 6) showing characteristic symptoms of aerial stem rot were observed in a field in Fengning Manchu Autonomous County, Chengde, Hebei Province (northern China)....

Pectobacterium species cause blackleg, soft rot and stem rot in potato and many other vegetable crops (Charkowski 2015). In July 2020, potato plants showing characteristic symptoms of aerial stem rot were observed in a field (cv. Xisen 6) in Fengning Manchu Autonomous County, Chengde, Hebei Province (North China). The disease incidence in that field (5 ha in size) was more than 50%. Putative pectolytic bacteria were obtained from symptomatic stem tissues (light brown and water-soaked stem sections) by culturing on the crystal violet pectate (CVP) medium. Bacterial colonies producing pits, were restreaked and purified on Luria-Bertani (LB) agar. The isolates causing stem rot were gram negative and rod shaped, negative for oxidase, urease, indole production, gelatin liquefaction and acid production from maltose and D-sorbitol. All isolates were catalase positive, produced acid from lactose, rhamnose, saccharose, raffinose and D-arabinose, and were tolerant to 5% NaCl, and able to utilize citrate. The bacterial gDNA was extracted using the EasyPure Bacteria Genomic DNA Kit (TransGen Biotech). The 16S rDNA region was amplified by PCR using the universal primer pair 27F/1492R and sequenced. Result of the Blastn analysis of the 16S rDNA amplicons (MZ379788, MZ379789) suggested that the isolates FN20111 and FN20121 belonged to the genus Pectobacterium. To determine the species of the stem rot Pectobacterium isolates, multi-locus sequence analysis (MLSA) was performed with six housekeeping genes acnA, gapA, icdA, mdh, proA and rpoS (MZ403781-MZ403792), and phylogenetic tree was reconstructed using RAxML v8.2.12 (https://github.com/stamatak/standard-RAxML). The result of phylogenetic analysis showed that the stem rot Pectobacterium isolates FN20111 and FN20121 clustered with P. versatile (syn. ‘Candidatus Pectobacterium maceratum’) strains CFBP6051T (Portier et al. 2019), SCC1 (Niemi et al. 2017) and F131 (Shirshikov et al. 2018). And the isolates FN20111 and FN20121 were more closely related to the type strain CFBP6051T than to strains SCC1 and F131. Potato seedlings (cv. Xisen 6 and Favorita) were inoculated with the isolates FN20111 and FN20121 by injecting 100 µl of bacterial suspensions (108 CFU·mL-1) into the upper parts of the stems of potato plants, or injected with 100 µl of 0.9% saline solution as control. The seedlings were grown at 28°C and 50% relative humidity. Three days post-inoculation, only the bacteria-inoculated seedlings showed diseased symptoms resembling to those observed in the field. Bacterial colonies were obtained from the infected stems and were identified using the same PCR primers of housekeeping genes as described above, fulfill Koch’s postulates. P. versatile causing soft rot and blackleg on potato plants has been reported in Finland (Niemi et al. 2017), Russia (Shirshikov et al. 2018), Netherlands (Portier et al. 2019), Poland (Waleron et al. 2019) and in New York State (Ma et al. 2021). To our knowledge, this is the first report of P. versatile causing aerial stem rot of potato in China.