Data from: Functional C-terminally encoded peptide (CEP) plant hormone domains evolved de novo in the plant parasite Rotylenchulus reniformis

Sedentary plant-parasitic nematodes (PPNs) induce and maintain an intimate relationship with their host, stimulating cells adjacent to root vascular tissue to re-differentiate into unique and metabolically active ‘feeding sites’. The interaction between PPNs and their host is mediated by nematode effectors. We describe the discovery of a large and diverse family of effector genes, encoding C-TERMINALLY ENCODED PEPTIDE (CEP) plant hormone mimics (RrCEPs), in the syncytia-forming plant parasite Rotylenchulus reniformis. The particular attributes of RrCEPs distinguish them from all other CEPs, regardless of origin. Together with the distant phylogenetic relationship of R. reniformis to the only other CEP-encoding nematode genus identified to date (Meloidogyne), this suggests that CEPs probably evolved de novo in R. reniformis. We have characterized the first member of this large gene family (RrCEP1), demonstrating its significant up-regulation during the plant–nematode interaction and expression in the effector-producing pharyngeal gland cell. All internal CEP domains of multi-domain RrCEPs are followed by di-basic residues, suggesting a mechanism for cleavage. A synthetic peptide corresponding to RrCEP1 domain 1 is biologically active and capable of up-regulating plant nitrate transporter (AtNRT2.1) expression, whilst simultaneously reducing primary root elongation. When a non-CEP-containing, syncytia-forming PPN species (Heterodera schachtii) infects Arabidopsis in a CEP-rich environment, a smaller feeding site is produced. We hypothesize that CEPs of R. reniformis represent a two-fold adaptation to sustained biotrophy in this species: (i) increasing host nitrate uptake, whilst (ii) limiting the size of the syncytial feeding site produced.固着型植物寄生线虫（Sedentary plant-parasitic nematodes, PPNs）可诱导并维持与宿主的紧密互作，促使根维管组织邻近细胞重新分化为独特且代谢活跃的“取食位点”。植物寄生线虫与宿主的互作由线虫效应蛋白介导。本研究报道了一类大型且多样的效应蛋白基因家族的发现，该家族编码羧基端编码肽（C-TERMINALLY ENCODED PEPTIDE, CEP）植物激素类似物（命名为RrCEPs），来自合胞体形成型植物寄生线虫肾形肾状线虫（Rotylenchulus reniformis）。RrCEPs的独特属性使其与所有来源的其他CEP家族成员均存在显著差异。结合目前已报道的唯一另一类编码CEP的线虫属——根结线虫属（Meloidogyne）与肾形肾状线虫的远缘系统发育关系，这一结果提示CEP家族很可能在肾形肾状线虫中从头演化而来。我们对该大型基因家族的首个成员RrCEP1进行了功能表征，结果显示其在植物-线虫互作过程中显著上调表达，且在效应蛋白产生的咽腺细胞中特异性表达。多结构域RrCEPs的所有内部CEP结构域后均紧随双碱性残基，这提示存在特定的切割加工机制。一段对应RrCEP1结构域1的合成肽具有生物学活性，可上调植物硝酸盐转运蛋白AtNRT2.1的表达，同时抑制主根伸长。当不含CEP的合胞体形成型植物寄生线虫甜菜孢囊线虫（Heterodera schachtii）在富含CEP的环境中侵染拟南芥（Arabidopsis）时，其产生的合胞体取食位点体积更小。我们推测，肾形肾状线虫的CEP家族代表了该物种适应持续活体营养的双重策略：（i）增强宿主的硝酸盐吸收能力，同时（ii）限制所形成的合胞体取食位点的大小。