BACKGROUND:Strawberry fruits are perishable with a short post-harvest life. Cinnamyl alcohol dehydrogenase (CAD) is the key enzyme for lignin biosynthesis strengthening plant cell wall. A systematic characterization of strawberry CAD family is absent and their involvement in fruit firmness is largely elusive. OBJECTIVE:Current work aims for a genome-wide identificationof CAD family and its expression correlation with fruit firmness in strawberry varieties. METHODS:A genome-scale identification and molecular characterization for CADs were performed in the commercial strawberry (Fragaria×ananassa) and woodland strawberry (F. vesca). qPCR analysis of CAD homoeologs in three cultivars varying with fruit firmness revealed candidate CAD members positively correlated with lignin content and fruit firmness. RESULTS:A total of 14 and 24 CAD loci were identified in the genomes of F.vesca var. Hawaii4 and F. ×ananassa cv. Camarosa, respectively.Phylogenetic analysis supported a division of this family into three classes. Class I FvCAD each has four homoeologs in commercial strawberry, while those of Class II and Class III have only one or two homoeologs. Except for FvCAD2 and -6, there exits at least one pair of CADs sharing ∼97% or above amino acid identity between F. vesca and F. ×ananassa.The flesh firmness and lignin content varied greatly among strawberry germplasm. Distinct dynamic changes in fruit lignin content were observed before the large green stage, but fruit firmness displayed a similar decrease profile during fruit development in three varieties. Of the eight genes detected in F.×ananassa, FvCAD3 and -12 did not display a F. vesca-biased expression pattern during fruit development.FvCAD4 of Class I was expressed at levels positively correlated with variation in fruit lignin content at white stage.Transcript abundance of five Class IIgenes including FvCAD3, -8, -10, -11, and -12 was positively correlated with lignin content and fruit firmness, with FvCAD10 and -11 (FaCAD in previous publication) reaching an extremely significant correlation with the genetic variation in fruit firmness across three varieties. CONCLUSION:Strawberry Class II CADs were significantly correlated with the genetic variation in fruit firmness,whichmight expand the potential choices for improving strawberry shelf life.

中文翻译：

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全基因组鉴定和表达分析揭示肉桂醇脱氢酶基因与草莓果实硬度相关

背景：草莓果实易腐烂，收获后寿命短。肉桂醇脱氢酶（CAD）是木质素生物合成强化植物细胞壁的关键酶。缺乏草莓 CAD 家族的系统特征，它们与果实硬度的关系在很大程度上难以捉摸。目的：目前的工作旨在全基因组鉴定 CAD 家族及其表达与草莓品种果实硬度的相关性。方法：在商业草莓（Fragaria×ananassa）和林地草莓（F. vesca）中进行CADs的基因组规模鉴定和分子表征。三个品种中 CAD 同源物的 qPCR 分析显示，候选 CAD 成员与木质素含量和果实硬度呈正相关。结果：在 F.vesca var. 的基因组中总共鉴定了 14 个和 24 个 CAD 基因座。Hawaii4 和 F. ×ananassa cv。Camarosa，分别。系统发育分析支持将该科分为三个类。I类FvCAD在商品草莓中各有4个同源物，而II类和III类FvCAD只有一两个同源物。除 FvCAD2 和 -6 外，F. vesca 和 F. ×ananassa 至少存在一对 CAD 共享约 97% 或以上的氨基酸同一性。草莓种质间果肉硬度和木质素含量差异很大。在大绿期之前观察到果实木质素含量的明显动态变化，但在三个品种的果实发育过程中果实硬度显示出相似的下降曲线。在 F.×ananassa 中检测到的 8 个基因中，FvCAD3 和 -12 没有显示 F. 果实发育过程中的vesca偏向表达模式。I类FvCAD4的表达水平与白色阶段果实木质素含量的变化呈正相关。包括FvCAD3、-8、-10、-11和-12在内的五个II类基因的转录丰度与木质素含量和果实硬度呈正相关，其中 FvCAD10 和 -11（先前出版物中的 FaCAD）与三个品种的果实硬度的遗传变异达到极其显着的相关性。结论:草莓II类CADs与果实硬度的遗传变异显着相关,为提高草莓保质期提供了可能的选择。包括 FvCAD3、-8、-10、-11 和 -12 在内的 5 个 II 类基因的转录本丰度与木质素含量和果实硬度呈正相关，其中 FvCAD10 和 -11（先前出版物中的 FaCAD）与遗传基因达到极其显着的相关性。三个品种的果实硬度变化。结论:草莓II类CADs与果实硬度的遗传变异显着相关,为提高草莓保质期提供了可能的选择。包括 FvCAD3、-8、-10、-11 和 -12 在内的 5 个 II 类基因的转录本丰度与木质素含量和果实硬度呈正相关，其中 FvCAD10 和 -11（先前出版物中的 FaCAD）与遗传基因达到极其显着的相关性。三个品种的果实硬度变化。结论:草莓II类CADs与果实硬度的遗传变异显着相关,为提高草莓保质期提供了可能的选择。