Project description:Transcriptional profile of sugarcane plants variety SP80-3280 inoculated with the pathogen Leifsonia xyli subsp. xyli (Lxx) compared with mocked inoculated ones 30 and 60 days after inoculation (DAI). Goal was to determine the effects of the increase in Lxx title on global sugarcane gene expression.
Project description:Sugarcane ratoon stunting disease (RSD) caused by Leifsonia xyli subsp. xyli (Lxx) is a common destructive disease that occurs around the world. Lxx is an obligate pathogen of sugarcane, and previous studies have reported some physiological responses of RSD-affected sugarcane. However, the molecular understanding of sugarcane response to Lxx infection remains unclear. In the present study, transcriptomes of healthy and Lxx-infected sugarcane stalks and leaves were studied to gain more insights into the gene activity in sugarcane in response to Lxx infection. RNA-Seq analysis of healthy and diseased plants transcriptomes identified 107,750 unigenes. Analysis of these unigenes showed a large number of differentially expressed genes (DEGs) occurring mostly in leaves of infected plants. Sugarcane responds to Lxx infection mainly via alteration of metabolic pathways such as photosynthesis, phytohormone biosynthesis, phytohormone action-mediated regulation, and plant-pathogen interactions. It was also found that cell wall defense pathways and protein phosphorylation/dephosphorylation pathways may play important roles in Lxx pathogeneis. In Lxx-infected plants, significant inhibition in photosynthetic processes through large number of differentially expressed genes involved in energy capture, energy metabolism and chloroplast structure. Also, Lxx infection caused down-regulation of gibberellin response through an increased activity of DELLA and down-regulation of GID1 proteins. This alteration in gibberellic acid response combined with the inhibition of photosynthetic processes may account for the majority of growth retardation occurring in RSD-affected plants. A number of genes associated with plant-pathogen interactions were also differentially expressed in Lxx-infected plants. These include those involved in secondary metabolite biosynthesis, protein phosphorylation/dephosphorylation, cell wall biosynthesis, and phagosomes, implicating an active defense response to Lxx infection. Considering the fact that RSD occurs worldwide and a significant cause of sugarcane productivity, a better understanding of Lxx resistance-related processes may help develop tools and technologies for producing RSD-resistant sugarcane varieties through conventional and/or molecular breeding.
Project description:BackgroundSugarcane is an important sugar and economic crop in the world. Ratoon stunting Disease (RSD) of sugarcane, caused by Leifsonia xyli subsp. xyli, is widespread in countries and regions where sugarcane is grown and also limited to sugarcane productivity. Although the whole genome sequencing of Leifsonia xyli subsp. xyli was completed, progress in understanding the molecular mechanism of the disease has been slow because it is difficult to grow in culture.ResultsThe Leifsonia xyli subsp. xyli membrane protein gene Lxx18460 (anti-sigma K) was cloned from the Lxx-infected sugarcane cultivar GT11 at the mature stage using RT-PCR technique, and the gene structure and expression in infected sugarcane were analyzed. The Lxx18460 gene was transformed into Nicotiana tabacum by Agrobacterium tumefaciens-mediation. The transgenic tobacco plants overexpressing Lxx18460 had lower levels in plant height, leaf area, net photosynthetic rate and endogenous hormones of IAA, ABA and GA3, as well as lower activities of three antioxidant enzymes, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) than the wild type (WT) tobacco. With the plant growth, the expression of Lxx18460 gene and protein was increased. To better understand the regulation of Lxx18460 expression, transcriptome analysis of leaves from transgenic and wild type tobacco was performed. A total of 60,222 all-unigenes were obtained through BGISEQ-500 sequencing. Compared the transgenic plants with the WT plants, 11,696 upregulated and 5949 downregulated genes were identified. These differentially expressed genes involved in many metabolic pathways including signal transduction, biosynthesis of other secondary metabolism, carbohydrate metabolism and so on. Though the data presented here are from a heterologous system, Lxx 18460 has an adverse impact on the growth of tobacco; it reduces the photosynthesis of tobacco, destroys the activity of defense enzymes, and affects the levels of endogenous hormones, which indicate that Lxx18460 may act important roles in the course of infection in sugarcane.ConclusionsThis is the first study on analyzing the function of the membrane protein gene Lxx18460 of anti-sigma K (σK) factor in Leifsonia xyli subsp. xyli. Our findings will improve the understanding of the interaction between the RSD pathogen Leifsonia xyli subsp. xyli and sugarcane. The output of this study will also be helpful to explore the pathogenesis of RSD.
Project description:Ratoon stunt, caused by the xylem-limited coryneform bacterium Leifsonia xyli subsp. xyli (Lxx), is a deep bacteriosis and prevalent in most of sugarcane-producing countries. Based on loop-mediated isothermal amplification (LAMP), we developed a method for detecting Lxx. The major advantages of the LAMP method are visual judgment by color and time saving with only 60?min for identification of Lxx and without the need for costly PCR apparatus and gel scanner. In the present study, positive and negative samples detected by the LAMP method were clearly distinguishable. When total DNA extracted from internode juice was used as the template, the sensitivity of LAMP was 10 times higher than that of the conventional PCR detection. The LAMP assay is a highly specific, rapid, and sensitive method for the diagnosis of ratoon stunt caused by Lxx in sugarcane. This is the first report of LAMP-based assay for the detection of Lxx in sugarcane.
Project description:We announce the complete genome sequence of Leifsonia xyli subsp. cynodontis, a vascular pathogen of Bermuda grass. The species also comprises Leifsonia xyli subsp. xyli, a sugarcane pathogen. Since these two subspecies have genome sequences available, a comparative analysis will contribute to our understanding of the differences in their biology and host specificity.
Project description:Leifsonia xyli subsp. xyli (Lxx) colonizes the xylem vessels of sugarcane, a plant niche where microorganisms are highly exposed to oxidative and osmotic stresses. This study performed an in silico analysis of the genome of Lxx and characterized 16 genes related to the detoxification of oxidative species (peroxidases, O2- dismutases, and methionine reductases) and to the production and transport of osmolytes and analyzed their expression in vitro after 30, 60, and 120 min of exposure to H2O2 or PEG. The PAGE activity of superoxide dismutase (Mn-SOD as confirmed by inhibition tests) and of catalase (CAT) and the accumulation of trehalose were also assessed. Exposure to H2O2 increased the expression of most oxidative-responsive genes and decreased the expression of those related to osmotic responses, whereas the opposite occurred after exposure to PEG. The isoform profiles of CAT and Mn-SOD shifted in response to H2O2 but not to PEG and Lxx cells accumulated more trehalose over time after exposure to PEG compared with non-exposed cells. The experimental results validated the in silico analysis and indicated that this obligate endophytic parasite has multiple and functional mechanisms to combat the stresses imposed by its host.