Yoshitake Yushi, Yoshimoto Kohki
Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1, Tama-ku, Kawasaki-shi, Kanagawa 214-8571, Japan.
Autophagy Rep. 2022 Jun 19;1(1):256-259. doi: 10.1080/27694127.2022.2089511. eCollection 2022.
Inorganic phosphate (Pi) is one of the most important nutrients for plant growth. Under Pi starvation, intracellular components are degraded for Pi recycling in plant cells. Macroautophagy/autophagy is a process for vacuolar degradation of cytoplasmic components including organelles, but it is still unclear whether this process is involved in plant growth and Pi recycling during Pi starvation. Recently, we reported that the degradation of endoplasmic reticulum (ER) by selective autophagy, termed reticulophagy, contributes to Pi recycling and is an important stress response in the early phase of Pi starvation. During this phase, oxidized lipids are accumulated in the plant cell in an iron ion-dependent manner, and this accumulation causes ER stress which induces reticulophagy. As a result, the Pi contents are maintained at a sufficient level during early Pi starvation, suppressing any late Pi starvation responses, such as membrane lipid remodeling. Thus, we proposed that ER stress-induced reticulophagy is an important Pi salvage system during the early phase of Pi starvation in plants.
无机磷酸盐（Pi）是植物生长最重要的养分之一。在Pi饥饿条件下，植物细胞内的成分会被降解以进行Pi循环利用。巨自噬/自噬是一个将包括细胞器在内的细胞质成分液泡降解的过程，但目前仍不清楚该过程是否参与Pi饥饿期间的植物生长和Pi循环利用。最近，我们报道了通过选择性自噬（称为网状自噬）对内质网（ER）的降解有助于Pi循环利用，并且是Pi饥饿早期的一种重要应激反应。在此阶段，氧化脂质以铁离子依赖的方式在植物细胞中积累，这种积累会导致ER应激，进而诱导网状自噬。结果，在Pi饥饿早期，Pi含量维持在足够水平，抑制了任何后期Pi饥饿反应，如膜脂重塑。因此，我们提出ER应激诱导的网状自噬是植物Pi饥饿早期重要的Pi挽救系统。
