Host-parasite tissue adhesion by a secreted type of β-1,4-glucanase in the parasitic plant Phtheirospermum japonicum

Abstract

Tissue adhesion between plant species occurs both naturally and artificially. Parasitic plants establish intimate relationship with host plants by adhering tissues at roots or stems. Plant grafting, on the other hand, is a widely used technique in agriculture to adhere tissues of two stems. Here we found that the model Orobanchaceae parasitic plant Phtheirospermum japonicum can be grafted on to interfamily species. To understand molecular basis of tissue adhesion between distant plant species, we conducted comparative transcriptome analyses on both infection and grafting by P. japonicum on Arabidopsis . Despite different organs, we identified the shared gene expression profile, where cell proliferation- and cell wall modification-related genes are up-regulated. Among genes commonly induced in tissue adhesion between distant species, we showed a gene encoding a secreted type of β-1,4-glucanase plays an important role for plant parasitism. Our data provide insights into the molecular commonality between parasitism and grafting in plants.

Vegetable Grafting From a Molecular Point of View: The Involvement of Epigenetics in Rootstock-Scion Interactions

“…However, it was recently proven that plants from different families even distant ones can be grafted successfully ( Notaguchi et al, 2020 ); phylogenetic proximity or similarity in the vascular anatomy of the grafting partners does not seem to result always in grafting realization ( Wulf et al, 2020 ). It is shown that grafting is facilitated by the action of genes such as cellulases that help the reconstruction of cell walls; these genes can facilitate tissue adhesion and promote plant grafting ( Kurotani et al, 2020 ; Notaguchi et al, 2020 ). If plants possess or are bred to possess such genes in abundance, interfamily barriers in grafting could be lifted and grafting technology can be expanded to deliver more chimeric plants that will take advantage of both distantly related partners’ advantages.…”

An in vitro grafting method to quantify mechanical forces of adhering tissues

“…We recently uncovered a key role of the GH9B3 clade of β-1,4-glucanases in cell-cell adhesion at the graft junction (Kurotani et al 2020;Notaguchi et al 2020). β-1,4-glucanases probably target cellulose in cell walls, and the overexpression of the β-1,4-glucanase gene promotes graft efficiency in Arabidopsis (Notaguchi et al 2020).…”

“…Using this system, we first showed that exogenous treatment with cellulases promotes graft adhesion. Given that numerous candidate genes related to grafting have been identified through recent transcriptome analyses (Chen et al 2017;Cookson et al 2014;Kurotani et al 2020;Li et al 2016;Liu et al 2016;Melnyk et al 2015;Notaguchi et al 2020;Wang H et al 2019;Xie et al 2019), methods for evaluating graft efficiency are required to test the roles of such genes. The IVG system can be applied to test the effect of genetic lines, environmental factors, and chemical treatments.…”

“…In regard to molecular mechanisms, studies have revealed the activity of enzymes, such as peroxidase and catalase, during grafting (Fernández-García et al 2004;Irisarri et al 2015;Pina and Errea 2008). Molecular genetic studies of grafting have been conducted in fruit trees, vegetables, and model plants (Chen et al 2017;Cookson et al 2014;Irisarri et al 2015;Kurotani et al 2020;Li et al 2016;Liu et al 2016;Matsuoka et al 2016Matsuoka et al , 2018Melnyk 2017;Melnyk et al 2015;Notaguchi et al 2020;Wang et al 2019;Wang et al 2014;Xie et al 2019). Among the various findings, these studies have clearly shown that grafting is promoted by auxin action through the expression of genes related to auxin signaling.…”

“…Among the various findings, these studies have clearly shown that grafting is promoted by auxin action through the expression of genes related to auxin signaling. The phytohormone auxin is transported basipetally from synthetic tissues, such as leaves and buds, by polar transport and accumulates at the damaged site (Chen et al 2017;Kurotani et al 2020;Liu et al 2016;Matsuoka et al 2016;Melnyk 2017;Melnyk et al 2015;Notaguchi et al 2020;Wang et al 2014;Yin et al 2012). Auxin promotes the formation of vascular strands when applied exogenously to undifferentiated tissue (Parkinson and Yeoman 1982;Wang et al 2014).…”