Knocking Down miR172f in the Hairy Roots of Grass Pea Increases β-ODAP Content and Induces Global Transcriptomic Reprogramming

<b>Background</b>: There is an abundance of the neuroactive β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP) in grass pea (<i>Lathyrus sativus</i>), pea (<i>Pisum sativum</i>), and several Chinese traditional herbs such as <i>Panax notoginseng</i>. It is well known for its dose- and context-dependent effects on its toxicological characteristics (inducing neurodegenerative neurolathyrism upon excessive consumption) or for its pharmacological effects (including neuroprotection and wound healing). Therefore, reducing β-ODAP levels improves the safety profile of β-ODAP-containing species for utilization, whereas increasing them facilitates their isolation and purification. <i>Ls</i>BAHD3 acyltransferase, named after the first letter of BEAT benzylalcohol O-acetyltransferase (BEAT), anthocyanin O-hydroxycinnamoyltransferase (AHCT), anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT), and deacetylvindoline 4-Oacetyltransferase (DAT), was proven to be β-ODAP synthetase. <b>Methods</b>: In this report, the interaction of miR172f with <i>LsBAHD3</i> was investigated through bioinformatic analysis and transient co-expression assays in <i>Nicotiana benthamiana</i>. Functions of miR172f in β-ODAP biosynthesis were also investigated through knockdown in the hairy roots of <i>L. sativus</i> and via transcriptomic analysis. <b>Results</b>: The results suggest that the knockdown of miR172f in hairy roots of <i>L. sativus</i> increased β-ODAP content via targets to <i>LsBAHD3</i>. In this process, protein ubiquitination, cysteine and methionine metabolism, enzyme regulator activity, and so on were associated with β-ODAP biosynthesis. <b>Conclusions</b>: These results identify miR172f as a novel regulator of β-ODAP biosynthesis through targeting of <i>LsBAHD3</i>, offering new insight into the gene expression of β-ODAP synthetase and the genetic network governing β-ODAP biosynthesis in <i>L. sativus</i>.