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Simple Summary Phospholipase D is the most important kind of phospholipase in plants, which can specifically catalyze the hydrolysis of phosphodiester bonds at the end of phospholipid molecules to produce phospholipid acid and a free group. Phospholipase D is not only involved in maintaining the structural stability of plant cell membrane and the dynamic balance of lipid composition but also involved in a variety of physiological processes, such as plant growth and development and stress response, including stomatal closure, root elongation, cell senescence, high salt stress, cold stress, and drought stress. It plays a critical role in plant growth and development, as well as in hormone and stress responses. In this study, the basic information on phospholipase D gene family was comprehensively introduced, and the physical and chemical properties, systematic evolution, gene structure, conservative motif, chromosome location, gene replication, cis-acting element prediction, GO annotation, interspecific collinearity, and quantitative analysis of potato phospholipase D gene family were analyzed to gain a better understanding of potato phospholipase D gene family. Through the analysis of potato phospholipase D gene family, our results lay the foundation for further understanding of the function of phospholipase gene family in higher plants. Abstract Phospholipase D (PLD) is the most important phospholipid hydrolase in plants, which can hydrolyze phospholipids into phosphatidic acid (PA) and choline. When plants encounter low temperature, drought and high salt stress, phospholipase D and its products play an important role in regulating plant growth and development and coping with stress. In this study, 16 members of StPLD gene family were identified in potato genome, which were distributed in α, β, δ, and ζ subfamilies, and their expression patterns under salt, high temperature, drought, and ABA stress were detected by qRT-PCR method. Gene expression analysis showed that the expression of StPLD genes in potato was upregulated and downregulated to varying degrees under the four stresses, indicating that the PLD gene family is involved in the interaction of potato plant hormones and abiotic stress signals. Chromosome distribution showed that StPLD gene was unevenly distributed on 8 chromosomes, and only one pair of tandem repeat genes was found. All StPLD promoters contain hormone and stress-related cis-regulatory elements to respond to different stresses. Structural analysis showed that StPLD genes in the same subgroup had a similar exon–intron structure. Our study provides a valuable reference for further research of the function and structure of PLD gene.

Alternative splicing (AS) is an important mechanism by which eukaryotes regulate transcription and protein diversity. The dynamic changes in AS that occur on a genome-wide scale during interactions between plant roots and pathogens remain unknown. Here, we used the interaction between Arabidopsis and Ralstonia solanacearum as a model to explore the AS changes that take place during the response of roots to infection by means of high-throughput RNA-sequencing. We showed that dynamic changes in AS occur much earlier than changes at the level of transcription during R.solanacearum infection. Comparing genes that are regulated at the transcriptional and AS levels indicated that there are few common genes between differentially spliced genes (DSGs) and differentially expressed genes (DEGs). The functional gene ontology (GO) analysis identified that the enriched GO terms for the DSGs were different from those of the DEGs. The DSGs were over-represented in GO terms associated with post-transcriptional and translational regulations, suggesting that AS may act on RNA stability and during post-translation, thus affecting the output of plant defense molecules. Meanwhile, changes in DSGs were infection stage-specific. Furthermore, the nucleotide binding domain and leucine-rich repeat proteins and receptor-like kinases, key regulators in plant immunity, were shown to undergo dynamic changes in AS in response to R. solanacearum. Taken together, AS, along with transcription, modulates plant root defense to R. solanacearum through transcriptome reprogramming.

[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).