Our newest work on transcellular progression of rhizobia is now out in Current Biology. Congratulations to Chao as the first author and all other team members for their contributions!
Su C, Zhang G, Rodriguez-France M, Hinnenberg R, Wietschorke J, Liang P, Yang W, Uhler L, Li X and Ott T (2023)
Transcellular progression of infection threads in Medicago truncatula roots is associated with locally confined cell wall modifications
Current Biology; 33:533-542
SUMMARY
The root nodule symbiosis with its global impact on nitrogen fertilization of soils is characterized by an intracellular colonization of legume roots by rhizobia. While the symbionts are initially taken up by morphologically adapted root hairs, rhizobia persistently progress within a membrane-confined infection thread through several root cortical and later nodular cell layers. Throughout this transcellular passaging, rhizobia have to repeatedly pass host plasma membranes and cell walls. Here, we investigated this essential process and describe the concerted action of one of the symbiosis-specific pectin methyl esterases (SyPME1) and the nodule pectate lyase NPL at the infection thread and transcellular passage sites. Their coordinated function mediates spatially confined pectin alterations in the cell-cell interface that result in the establishment of an apoplastic compartment where bacteria are temporarily released into and taken up from the subjacent cell. This process allows successful intracellular progression of infection threads through the entire root cortical tissue.
