Autophagy is induced during plant grafting for wound healing

Abstract

l Grafting is an important technique in agriculture to obtain several good traits such as high disease tolerance and high yield by exchanging root system. However, the underlined cellular processes to compensate the wound damage and repair tissues were largely unknown. l We analyzed two graft combinations: Nicotiana benthamiana (Nb) homograft as a compatible, wound repairing model and Nb heterograft with Arabidopsis thaliana (At)as an incompatible and more stressful model, which we recently identified as an exceptional maintainable interfamily grafting. l In both graft combinations, nutrient loss was observed in gene expression after grafting, where the level of nutrient loss was more sever in heterografts. Transmission electron micrographs of Nb/At heterografts suggested that microautophagy was induced in cells near the graft boundary. In At seedling micrografting, the fluorescence of autophagy protein marker GFP-ATG8 was highly observed at graft junction especially in cambial region. In At atg2 mutant homografts, growth after grafting decreased compared with wild-type homografts. Moreover, when NbATG5 knockeddown Nb scion was grafted to At stock, the successful rate of grafting was significantly decreased. l Altogether, these results suggest that component of autophagy is induced during grafting and has a role in wound healing.

Autophagy–mediated plasma membrane removal promotes the formation of epithelial syncytia

“…In plants, rats and mice, autophagy is in turn necessary for efficient wound healing. Plant grafting induces autophagy at the site of the wound and lack of Atg2 or Atg5 reduces the rate of successful grafting (Kurotani et al , 2020). Wounding mouse skin induces the expression of autophagy genes in the epidermis and some of these genes (Atg5 or Atg7) are needed for proper wound closure, infiltration by immune cells, and for the production of cytokine CCL2.…”

“…Wounding has been shown in Drosophila , planarians, zebrafish, rat, mouse and plants to induce autophagy (Varga et al , 2014; Kakanj et al , 2016; Kang et al , 2019; Allen & Baehrecke, 2020; Chavez et al , 2020; Kurotani et al , 2020; Qiang et al , 2020; Xu et al , 2020). In plants, rats and mice, autophagy is in turn necessary for efficient wound healing.…”

Autophagy suppression by TORC1 maintains epithelial plasma membrane integrity and inhibits syncytium formation

“…In plants, rats and mice, autophagy is in turn necessary for efficient wound healing. Plant grafting induces autophagy at the site of the wound and lack of Atg2 or Atg5 reduces the rate of successful grafting 7 . Wounding mouse skin induces the expression of autophagy genes in the epidermis and some of these genes (Atg5 or Atg7) are needed for proper wound closure, infiltration by immune cells, and for the production of cytokine CCL2.…”

“…Wounding has been shown in Drosophila, planarians, zebrafish, rat, mouse and plants to induce autophagy 1,[6][7][8][9][10][11][12] . In plants, rats and mice, autophagy is in turn necessary for efficient wound healing.…”