Hi! Thanks for your nice question! sHsp is a big family, containing Acd proteins. This Acd protein is also annotated as a sHsp protein. We haven’t done experiment to check if it indeed is a small Hsp protein, but it’s worth to do this in future!

Thanks to everyone involved in this work
@qunliu07.bsky.social, Anna Neefjes, Roksolana Kobylinska, @samtmugford.bsky.social, @mmarzo.bsky.social, James Canham (@thesainsburylab.bsky.social), @marischuster.bsky.social, Renier van der Hoorn,
Yazhou Chen, @saskiahogenhout.bsky.social

Interestingly we found that CathBs also interact with a Hsp20 chaperone, and that this can inhibit the relocalisation of EDS1 and restore aphid resistance, identifying the Hsp20 Acd28.9 as a resistance factor to aphids.

We found CathBs interact with the key immune regulatory protein EDS1, and pull it into p-bodies away from its normal locations, and that this interrupts normal immune signaling pathways.

Here we show that Cathepsin Bs are present in aphid oral secretions, and localised to p-bodies in the plant cell. P-bodies are canonically involved in storage of mRNA, so what is an aphid Cathepsin doing in there?

We previously described a gene family expansion of cathepsin Bs in the green peach aphid Myzus persicae that reduce plant resistance to aphids, but we did not know the mechanism.