Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, India.
Bionivid Technology Private Limited, 209, 4th Cross, Kasturi Nagar, Bangalore, India.
BMC Genomics. 2018 Nov 29;19(1):850. doi: 10.1186/s12864-018-5230-8.
Southern root-knot nematode Meloidogyne incognita (Kofoid and White, 1919), Chitwood, 1949 is a key pest of agricultural crops. Pasteuria penetrans is a hyperparasitic bacterium capable of suppressing the nematode reproduction, and represents a typical coevolved pathogen-hyperparasite system. Attachment of Pasteuria endospores to the cuticle of second-stage nematode juveniles is the first and pivotal step in the bacterial infection. RNA-Seq was used to understand the early transcriptional response of the root-knot nematode at 8 h post Pasteuria endospore attachment.
A total of 52,485 transcripts were assembled from the high quality (HQ) reads, out of which 582 transcripts were found differentially expressed in the Pasteuria endospore encumbered J2 s, of which 229 were up-regulated and 353 were down-regulated. Pasteuria infection caused a suppression of the protein synthesis machinery of the nematode. Several of the differentially expressed transcripts were putatively involved in nematode innate immunity, signaling, stress responses, endospore attachment process and post-attachment behavioral modification of the juveniles. The expression profiles of fifteen selected transcripts were validated to be true by the qRT PCR. RNAi based silencing of transcripts coding for fructose bisphosphate aldolase and glucosyl transferase caused a reduction in endospore attachment as compared to the controls, whereas, silencing of aspartic protease and ubiquitin coding transcripts resulted in higher incidence of endospore attachment on the nematode cuticle.
Here we provide evidence of an early transcriptional response by the nematode upon infection by Pasteuria prior to root invasion. We found that adhesion of Pasteuria endospores to the cuticle induced a down-regulated protein response in the nematode. In addition, we show that fructose bisphosphate aldolase, glucosyl transferase, aspartic protease and ubiquitin coding transcripts are involved in modulating the endospore attachment on the nematode cuticle. Our results add new and significant information to the existing knowledge on early molecular interaction between M. incognita and P. penetrans.
南方根结线虫 Meloidogyne incognita（Kofoid 和 White，1919），Chitwood，1949 是农业作物的主要害虫。多粘类芽孢杆菌是一种能够抑制线虫繁殖的超寄生细菌，代表了一种典型的共同进化的病原体-超寄生系统。多粘类芽孢杆菌内生孢子附着在第二阶段线虫幼虫的表皮上，是细菌感染的第一步和关键步骤。RNA-Seq 用于了解根结线虫在被多粘类芽孢杆菌内生孢子附着后 8 小时的早期转录反应。
从高质量（HQ）读数中组装了总共 52485 个转录本，其中在被多粘类芽孢杆菌内生孢子包裹的 J2 中发现有 582 个转录本差异表达，其中 229 个上调，353 个下调。多粘类芽孢杆菌感染抑制了线虫的蛋白质合成机制。一些差异表达的转录本推测参与了线虫先天免疫、信号转导、应激反应、内生孢子附着过程和幼虫附着后行为修饰。通过 qRT-PCR 验证了 15 个选定转录本的表达谱是真实的。与对照相比，编码果糖二磷酸醛缩酶和葡萄糖基转移酶的转录本的 RNAi 沉默导致内生孢子附着减少，而天冬氨酸蛋白酶和泛素编码转录本的沉默导致内生孢子附着在线虫表皮上的发生率更高。
本文提供了在根入侵之前，线虫感染多粘类芽孢杆菌时的早期转录反应证据。我们发现，多粘类芽孢杆菌内生孢子附着在表皮上，导致线虫的蛋白质反应下调。此外，我们表明果糖二磷酸醛缩酶、葡萄糖基转移酶、天冬氨酸蛋白酶和泛素编码转录本参与调节内生孢子在线虫表皮上的附着。我们的研究结果为南方根结线虫和多粘类芽孢杆菌之间的早期分子相互作用提供了新的重要信息。
