Data_Sheet_1_Metabolic, Enzymatic Activity, and Transcriptomic Analysis Reveals the Mechanism Underlying the Lack of Characteristic Floral Scent in Apricot Mei Varieties.docx

Apricot mei, a hybrid of Prunus mume and Prunus sibirica, usually has greater cold resistance than P. mume; however, most varieties of Apricot mei lack the characteristic floral scent of P. mume. The volatile and intracellular metabolites, activity levels of key enzymes, and transcriptomes of blooming flowers were comprehensively investigated in five varieties of P. mume. Benzyl acetate and eugenol were determined to be the main components of the P. mume floral scent. However, benzyl benzoate and benzyl alcohol benzoyltransferase activity was detected in only the low-fragrance varieties “Dan Fenghou” and “Yanxing.” No benzyl alcohol or benzaldehyde reductase (BAR) activity was detected in the non-fragrant variety “Fenghou.” PmBAR1 and PmBAR3 were identified as the key genes responsible for BAR activity. The lack of benzyl alcohol synthesis in the “Fenghou” variety was caused by low activity of PmBAR1-Fen and low expression of PmBAR3. The 60-aa segment at the N-terminus of PmBAR3 was found to play an important role in its enzymatic activity. Correlation tests between floral scent metabolites and the transcriptomes of the five different scented varieties showed that some transcripts associated with hormones, stresses, posttranslational modifications and transporters may also play important regulatory roles in floral scent metabolism in the different varieties.

杏梅（Apricot mei）为梅（Prunus mume）与山杏（Prunus sibirica）的杂交品种，其耐寒性通常优于梅；但多数杏梅品种缺失梅所特有的花香特征。本研究对5个梅品种的盛开花朵的挥发性代谢物、胞内代谢物、关键酶活性及转录组开展了全面解析。经检测，乙酸苄酯与丁香酚为梅花香的核心成分。仅在低花香品种‘丹凤后’与‘烟杏’中检出苯甲酸苄酯及苯甲醇苯甲酰基转移酶活性；而在无香品种‘凤后’中未检测到苯甲醇或苯甲醛还原酶（benzaldehyde reductase, BAR）活性。PmBAR1与PmBAR3被鉴定为调控BAR活性的关键基因。‘凤后’品种无法合成苯甲醇，其原因在于PmBAR1-Fen的酶活性低下，且PmBAR3的表达水平不足。研究发现，PmBAR3的N端60个氨基酸片段对其酶活性具有关键调控作用。针对5个不同花香表型的梅品种的花香代谢物与转录组开展相关性分析，结果显示部分与激素响应、胁迫应答、翻译后修饰及转运蛋白相关的转录本，在不同品种的花香代谢调控过程中同样发挥了重要作用。