Suchergebnisse

Bacterial wilt caused by the bacterial pathogen Ralstonia solanacearum is one of the most devastating crop diseases worldwide. The molecular mechanisms controlling the early stage of R. solanacearum colonization in the root remain unknown. Aiming to better understand the mechanism of the establishment of R. solanacearum infection in root, we established four stages in the early interaction of the pathogen with Arabidopsis roots and determined the transcriptional profiles of these stages of infection. A total 2,698 genes were identified as differentially expressed genes during the initial 96 h after infection, with the majority of changes in gene expression occurring after pathogen-triggered root-hair development observed. Further analysis of differentially expressed genes indicated sequential activation of multiple hormone signaling cascades, including abscisic acid (ABA), auxin, jasmonic acid, and ethylene. Simultaneous impairment of ABA receptor genes promoted plant wilting symptoms after R. solanacearum infection but did not affect primary root growth inhibition or root-hair and lateral root formation caused by R. solanacearum. This indicated that ABA signaling positively regulates root defense to R. solanacearum. Moreover, transcriptional changes of genes involved in primary root, lateral root, and root-hair formation exhibited high temporal dynamics upon infection. Taken together, our results suggest that successful infection of R. solanacearum on roots is a highly programmed process involving in hormone crosstalk. ; This study was supported by the National Natural Science Foundation of China (No. 31601703), the Start-up Funds of Northwest A&F University (Z111021601), the Fundamental Research Fund for the Central Universities of China (Z109021706) and External Science and Technology Cooperation Program of Ningxia Academy of Agriculture and Forestry Sciences (DW-X-2018012). We also acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (grants AGL2016-78002-R and SEV-2015-0533) and from the CERCA project of the Catalan Government (Generalitat de Catalunya). ; Peer reviewed

[Background]: Potato, the third most important crop worldwide, plays a critical role in human food security. Brown rot, one of the most destructive potato diseases caused by Ralstonia solanacearum, results in huge economic losses every year. A quick, stable, low cost and high throughout method is required to meet the demands of identification of germplasm resistance to bacterial wilt in potato breeding programs. ; [Results]: Here we present a novel R. solanacearum hydroponic infection assay on potato plants grown in vitro. Through testing wilt symptom appearance and bacterial colonization in aerial part of plants, we found that the optimum conditions for in vitro potato infection were using an OD600 0.01 bacterial solution suspended with tap water for infection, broken potato roots and an open container. Infection using R. solanacearum strains with differential degree of aggressivity demonstrated that this infection system is equally efficient as soil-drench inoculation for assessment of R. solanacearum virulence on potato. A small-scale assessment of 32 potato germplasms identified three varieties highly resistant to the pathogen, which indicates this infection system is a useful method for high-throughout screening of potato germplasm for resistance. Furthermore, we demonstrate the utility of a strain carrying luminescence to easily quantify bacterial colonization and the detection of latent infections in hydroponic conditions, which can be efficiently used in potato breeding programs. ; [Conclusions]: We have established a quick and efficient in vitro potato infection system, which may facilitate breeding for new potato cultivars with high resistance to R. solanacearum. ; This study was supported by the National Natural Science Foundation of China (No. 31601703), the Start-up Funds of Northwest A&F University (Z111021601), the Fundamental Research Fund for the Central Universities of China (Z109021706) and External Science and Technology Cooperation Program of Ningxia Academy of Agriculture and Forestry Sciences (DW-X-2018012). N.S.C. and M.V. work was funded by projects AGL2016-78002-R. (Spanish Ministry of Economy and Competitiveness) and financial support from the "Severo Ochoa Programme for Centres of Excellence in R&D" (SEV‐2015‐0533) and the CERCA Programme from the Catalan Government (Generalitat de Catalunya). ; Peer reviewed