Department of Plant Pathology and Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Athens, Georgia, USA.
Division of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA.
Mol Plant Pathol. 2022 Dec;23(12):1765-1782. doi: 10.1111/mpp.13263. Epub 2022 Sep 7.
Plant-parasitic cyst nematodes use a stylet to deliver effector proteins produced in oesophageal gland cells into root cells to cause disease in plants. These effectors are deployed to modulate plant defence responses and developmental programmes for the formation of a specialized feeding site called a syncytium. The Hg2D01 effector gene, coding for a novel 185-amino-acid secreted protein, was previously shown to be up-regulated in the dorsal gland of parasitic juveniles of the soybean cyst nematode Heterodera glycines, but its function has remained unknown. Genome analyses revealed that Hg2D01 belongs to a highly diversified effector gene family in the genomes of H. glycines and the sugar beet cyst nematode Heterodera schachtii. For functional studies using the model Arabidopsis thaliana-H. schachtii pathosystem, we cloned the orthologous Hs2D01 sequence from H. schachtii. We demonstrate that Hs2D01 is a cytoplasmic effector that interacts with the intracellular kinase domain of HAESA (HAE), a cell surface-associated leucine-rich repeat (LRR) receptor-like kinase (RLK) involved in signalling the activation of cell wall-remodelling enzymes important for cell separation during abscission and lateral root emergence. Furthermore, we show that AtHAE is expressed in the syncytium and, therefore, could serve as a viable host target for Hs2D01. Infective juveniles effectively penetrated the roots of HAE and HAESA-LIKE2 (HSL2) double mutant plants; however, fewer nematodes developed on the roots, consistent with a role for this receptor family in nematode infection. Taken together, our results suggest that the Hs2D01-AtHAE interaction may play an important role in sugar beet cyst nematode parasitism.
植物寄生性囊线虫使用口针将食道腺细胞产生的效应蛋白输送到根细胞中，从而在植物中引起疾病。这些效应子被用来调节植物防御反应和发育程序，以形成一种称为合胞体的专门取食部位。Hg2D01 效应基因，编码一种新型的 185 个氨基酸分泌蛋白，先前被证明在大豆胞囊线虫寄生幼虫的背腺中上调，但它的功能仍然未知。基因组分析表明，Hg2D01 属于 H. glycines 和甜菜胞囊线虫 H. schachtii 基因组中高度多样化的效应基因家族。为了使用模式拟南芥- H. schachtii 病理系统进行功能研究，我们从 H. schachtii 中克隆了同源的 Hs2D01 序列。我们证明 Hs2D01 是一种细胞质效应子，与细胞内激酶域的 HAESA（HAE）相互作用，HAE 是一种细胞表面相关的富含亮氨酸重复（LRR）受体样激酶（RLK），参与信号转导细胞壁重塑酶的激活，这些酶对于细胞分离很重要脱落和侧根出现。此外，我们表明 AtHAE 在合胞体中表达，因此可以作为 Hs2D01 的可行宿主靶标。感染性幼虫有效地穿透了 HAE 和 HAESA-LIKE2（HSL2）双突变体植物的根；然而，在根上发育的线虫较少，这与该受体家族在线虫感染中的作用一致。总之，我们的结果表明，Hs2D01-AtHAE 相互作用可能在甜菜胞囊线虫寄生中发挥重要作用。
