Plant plasmodesmata (PDs) are specialized channels that enable communication between neighboring cells. The intercellular permeability of PDs, which affects plant development, defense, and responses to stimuli, must be tightly regulated. However, the lipid compositions of PD membrane and their impact on PD permeability remain elusive. Here, we report that the Arabidopsis sld1 sld2 double mutant, lacking sphingolipid long-chain base 8 desaturases 1 and 2, displayed decreased PD permeability due to a significant increase in callose accumulation. PD-located protein 5 (PDLP5) was significantly enriched in the leaf epidermal cells of sld1 sld2 and showed specific binding affinity to phytosphinganine (t18:0), suggesting that the enrichment of t18:0-based sphingolipids in sld1 sld2 PDs might facilitate the recruitment of PDLP5 proteins to PDs. The sld1 sld2 double mutant seedlings showed enhanced resistance to the fungal-wilt pathogen Verticillium dahlia and the bacterium Pseudomonas syringae pv. tomato DC3000, which could be fully rescued in sld1 sld2 pdlp5 triple mutant. Taken together, these results indicate that phytosphinganine might regulate PD functions and cell-to-cell communication by modifying the level of PDLP5 in PD membranes.

植物胞浆菌（PD）是专门的通道，可实现相邻细胞之间的通信。PD的细胞间渗透性会影响植物的发育，防御和对刺激的反应，因此必须进行严格调节。但是，PD膜的脂质组成及其对PD渗透性的影响仍然难以捉摸。在这里，我们报告的拟南芥sld1 sld2双突变体，缺乏鞘脂长链碱基8去饱和酶1和2，由于call积累的显着增加，显示PD渗透性降低。PD定位蛋白5（PDLP5）在sld1 sld2的叶表皮细胞中显着富集，并显示出对植物鞘氨醇（t18：0）的特异性结合亲和力，这表明基于t18：0的鞘脂的富集sld1 sld2 PD可能有助于将PDLP5蛋白募集到PD。所述SLD1 SLD2双突变体幼苗表现出增强的抗真菌枯萎病原体黄萎病大丽花和细菌丁香假单胞菌PV。番茄DC3000，可以在sld1 sld2 pdlp5三重突变体中完全拯救。综上所述，这些结果表明植物鞘氨醇可能通过改变PD膜中PDLP5的水平来调节PD的功能和细胞间的通讯。