木薯支链氨基酸代谢关键基因挖掘OA

Animals cannot synthesize branched-chain amino acids(BCAAs)endogenously and must obtain BCAAs from the diet.The BCAAs content in crops becomes a key nutritional indicator.Branched-chain aminotransferase(BCAT)is the sole enzyme responsible for both the biosynthesis and catabolism of BCAAs,positioning it as a pivotal regulatory hub in BCAA metabolism.Using the cassava cultivar SC205,we integrated metabolomic and transcriptomic datasets to identify MeBCAT1 and MeBCAT3 as key genes involved in BCAA metabolic pathways.Bioinformatic characterization and quantitative real-time PCR were employed to profile the tissue-specific expression patterns of the genes,and the subcellular localization was examined using a transient expression system in Nicotiana benthamiana leaf epidermal cells.Both crude protein content and BCAAs abundance were significantly higher in cassava leaves than in tuberous roots.The cassava BCAT gene family consisted of eight members unevenly distributed across five chromosomes.Phys-icochemical analysis revealed that the encoded polypeptides ranged from 387 to 1,000 amino acids in length,with pre-dicted isoelectric points(pI)ranging from 5.56 to 8.96.Synteny analysis indicated that segmental duplication events served as the predominant driving force underlying the expansion of the cassava BCAT gene family.Further transcrip-tomic evaluation uncovered substantial divergence in the transcriptional abundance of MeBCAT1 and MeBCAT3,both genes exhibited pronounced expression in foliar tissues,with MeBCAT1 showing particularly high transcript levels.MeBCAT1 and MeBCAT3 encoded polypeptides of 387 and 450 amino acid residues,respectively,and subcellular lo-calization assays confirmed that both proteins were localized in the mitochondria.Together,our findings show that cas-sava leaves are a rich source of essential BCAAs for animal development and MeBCAT1 is a key genetic regulator of BCAA metabolism.This study thus would offer a theoretical framework for enhancing cassava's nutritional quality as a feed crop and establishes a foundation for dissecting the molecular mechanisms of BCAA metabolism in this staple crop.