College of Agriculture, Guangxi University, Nanning, Guangxi, China.
Ministry of Agriculture Key Laboratory of Sugarcane Biotechnology and Genetic Improvement (Guangxi), Guangxi Key Laboratory of Sugarcane Genetic Improvement, Sugarcane Research Center, Chinese Academy of Agricultural Sciences, Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, Guangxi, China.
PLoS One. 2021 Feb 2;16(2):e0245613. doi: 10.1371/journal.pone.0245613. eCollection 2021.
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.
甘蔗丛矮缩病（RSD）由木聚糖分解木质杆菌亚种木聚糖（Lxx）引起，是一种常见的破坏性疾病，在世界各地都有发生。Lxx 是甘蔗的专性病原体，先前的研究报道了一些受 RSD 影响的甘蔗的生理反应。然而，甘蔗对 Lxx 感染的分子理解仍不清楚。在本研究中，研究了健康和 Lxx 感染的甘蔗茎和叶片的转录组，以更深入地了解甘蔗对 Lxx 感染的基因活性。对健康和患病植物转录组的 RNA-Seq 分析鉴定了 107750 个单基因。对这些单基因的分析表明，大量差异表达基因（DEGs）主要发生在感染植物的叶片中。甘蔗主要通过改变代谢途径来响应 Lxx 感染，如光合作用、植物激素生物合成、植物激素作用介导的调节以及植物-病原体相互作用。还发现细胞壁防御途径和蛋白质磷酸化/去磷酸化途径可能在 Lxx 发病机制中发挥重要作用。在 Lxx 感染的植物中，大量参与能量捕获、能量代谢和叶绿体结构的差异表达基因导致光合作用过程受到显著抑制。此外，Lxx 感染通过增加 DELLA 的活性和下调 GID1 蛋白导致赤霉素反应的下调。这种赤霉素反应的改变与光合作用过程的抑制共同导致了 RSD 感染植物中大部分生长迟缓的发生。一些与植物-病原体相互作用相关的基因在 Lxx 感染的植物中也表现出差异表达。这些基因包括参与次生代谢物生物合成、蛋白质磷酸化/去磷酸化、细胞壁生物合成和吞噬体的基因，表明对 Lxx 感染存在主动防御反应。考虑到 RSD 在全球范围内发生并且是甘蔗生产力的主要原因之一，更好地理解与 Lxx 抗性相关的过程可能有助于通过传统和/或分子育种开发生产 RSD 抗性甘蔗品种的工具和技术。
