Enlarging the throughfare
Plant cells are surrounded by cell walls. To stay in contact with their neighbours they have those tunnel like structures, called plasmodesmata. Through these tunnels small molecules can travel from cell to cell. But pathogens also use these throughfares. Now English researchers show that pathogens enlarge these tunnels in a still unknown way.
Plasmodesmta connect neighbouring cells. Through these tunnels molecules can travel from cell to cell. How quickly, that depends on their size. But also if they can adjust the throughfare of these tunnels. This also counts for molecules excreted by pathogens, the so called effectors, they also use these throughfares.
To find out more about the influence of these effectors on plasmodesmata, the researchers studied the mobility of these effectors. Doing this they developed a mobility score for molecules of different sizes. Subsequently they compared the actual mobility of the effectors with the expected mobility score based on their size. Discovering three effectors that behaved differently, their mobility score was higher than expected.
The effectors enlarge the throughfare, but how is still unknown
Subsequently the researchers analysed why these effectors had a higher mobility score. The first thing they checked was if the effectors adjusted the size of the tunnels. Using a fluorescent protein that under normal conditions does not fit through the tunnel. But in the presence of two of the effectors this fluorescent protein could pass through. The effectors increased the tunnel size.
The question remained how they did this. The most logical explanation would be that these effectors were physically adjusting the size. To check this the researchers analysed if the effectors contacted the tunnel edges. This turned out not to be the case. The effectors also did not have an effect on known plasmodesmata influencing genes.
They show there is a still unknown way through which molecules can effect plasmodesmata size. For this this study show the first indicators.
Literature
Mina Ohtsu, DJoanna Jennings, Matthew G. Johnston, Andrew Breakspear, Xiaokun Liu, Kara Stark, Richard Morris, Jeroen de Keijzer, and Christine Faulkner (2023) Assaying effector cell-to-cell mobility in plant tissues identifies hypermobility and indirect manipulation of plasmodesmata. Molecular Plant-Microbe Interactions https://doi.org/10.1094/MPMI-05-23-0052-TA
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