Plant & zo
The science of plants and more
A fast response is needed when pathogenic bacteria or fungi enters a plant. Then the plant can try to actively stop this intruder, starting an immune reaction. For this, the recogniser sends a message to the whole cell, who in turn forwards it to the whole plant. Like a relay. Although most of the participants of this relay are known, up till now it was still unknown how the transfer between the first and second participants takes place.
To find out Chinese and German researchers studied the transfer between the recogniser, the TIR-receptor, and the next runner, the EDS1-PAD4 complex. A relay runner can only do the transfer with the next runner after the transfer of the previous runner took place. Therefore, the researchers analysed what EDS1-PAD4 was carrying when it did its next transfer. This allowed the researchers to discover that EDS1-PAD4 carried the messenger pRip-AMP or pRip-ADP when it did the subsequent transfer. Only with one of these two messengers EDS1-PAD4 could do the next transfer. Suggesting that the TIR-receptor transfers pRip-AMP/ADP to EDS1-PAD4.
The pRip-AMP/ADP messengers are an important link in starting the defence against intruders
Although confirming this turned out to be a bit of a headage, as pRip-AMP/ADP breaks down quickly when there is no EDS1-PAD4 to hold it. To get around this the researchers made use of two type of cells. Firstly, plant cells with the TIR-receptor, but without EDS1-PAD4. And secondly, insect cells with EDS1-PAD4, but without the TIR-receptor. These they mixed, and broke them open only after that, so that any pRip-AMP/ADP could find a EDS1-PAD4 complex to hold on to. What they found: EDS1-PAD4 holding pRip-AMP.
The TIR-receptor produces pRip-AMP messengers to start off the immune reaction relay. The pRip-AMP/ADP messengers are an important link in starting the defence against intruders. Now knowing the messengers of the intruder-recognisers we can work on protecting plants better against those unwanted intruders. Keeping our plants healty.
Jia A., Huang S., Song W., Wang J., Meng Y., Sun Y., Xu L., Laessle H., Jirschitzka J., Hou J., Zhang T., Yu W., Hessler G., Li E., Ma S., Yu D., Gebauer J., Baumann U., Liu X., Han Z., Chang J., Parker J.E., and Chai J. (2022) TIR-catalyzed ADP-ribosylation reactions produce signaling molecules for plant immunity. Science DOI: 10.1126/science.abq8180