Inactive auxin conjugates are accumulated in plants and hydrolyzed to recover phytohormone action. A family of metallopeptidase orthologues has been conserved in Plantae to help regulate auxin homeostatic levels during growth and development. This hydrolase family was recently traced back to liverwort, the most ancient extant land plant lineage. Liverwort’s auxin hydrolase has little activity against auxin conjugate substrates and does not appear to actively regulate auxin. This finding, along with data that shows moss can synthesize auxin conjugates, led to examining another bryophyte lineage, Physcomitrella patens. We have identified and isolated three M20D hydrolase paralogues from moss. The isolated enzymes strongly recognize and cleave a variety of auxin conjugates, including those of indole butyric and indole propionic acids. These P. patens hydrolases not only appear to be “cryptic”, but they are likely to have derived from soil bacteria through Horizontal Gene Transfer. Additionally, support is presented that the plant-type M20D peptidase family may have been universally lost from mosses after divergence from the common ancestor with liverwort.

中文翻译：

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来自苔藓的 M20D 生长素酰胺水解酶家族早期进化丢失的证据以及从隐性水解酶直向同源物的土壤细菌到 Physcomitrella patens 的水平基因转移的证据

无活性的生长素结合物在植物中积累并水解以恢复植物激素作用。金属肽酶直向同源物家族在植物中被保守，以帮助调节生长和发育过程中的生长素稳态水平。这个水解酶家族最近可以追溯到地草，这是现存最古老的陆生植物谱系。Liverwort 的植物生长素水解酶对植物生长素结合底物几乎没有活性，并且似乎不会主动调节植物生长素。这一发现，连同显示苔藓可以合成生长素结合物的数据，导致了对另一个苔藓植物谱系——Physcomitrella patens 的研究。我们已经从苔藓中鉴定并分离出三个 M20D 水解酶旁系同源物。分离的酶能强烈识别并裂解多种生长素结合物，包括吲哚丁酸和吲哚丙酸的结合物。这些P。patens 水解酶不仅看起来“神秘”，而且很可能是通过水平基因转移从土壤细菌中提取的。此外，支持植物型 M20D 肽酶家族可能在与苔藓的共同祖先发生分歧后从苔藓中普遍消失。