Table_3_Genome-wide identification, phylogeny, and expression analysis of GRF transcription factors in pineapple (Ananas comosus).xlsx

BackgroundPineapple is the only commercially grown fruit crop in the Bromeliaceae family and has significant agricultural, industrial, economic, and ornamental value. GRF (growth-regulating factor) proteins are important transcription factors that have evolved in seed plants (embryophytes). They contain two conserved domains, QLQ (Gln, Leu, Gln) and WRC (Trp, Arg, Cys), and regulate multiple aspects of plant growth and stress response, including floral organ development, leaf growth, and hormone responses. The GRF family has been characterized in a number of plant species, but little is known about this family in pineapple and other bromeliads.
Main discoveriesWe identified eight GRF transcription factor genes in pineapple, and phylogenetic analysis placed them into five subfamilies (I, III, IV, V, VI). Segmental duplication appeared to be the major contributor to expansion of the AcGRF family, and the family has undergone strong purifying selection during evolution. Relative to that of other gene families, the gene structure of the GRF family showed less conservation. Analysis of promoter cis-elements suggested that AcGRF genes are widely involved in plant growth and development. Transcriptome data and qRT-PCR results showed that, with the exception of AcGRF5, the AcGRFs were preferentially expressed in the early stage of floral organ development and AcGRF2 was strongly expressed in ovules. Gibberellin treatment significantly induced AcGRF7/8 expression, suggesting that these two genes may be involved in the molecular regulatory pathway by which gibberellin promotes pineapple fruit expansion.
ConclusionAcGRF proteins appear to play a role in the regulation of floral organ development and the response to gibberellin. The information reported here provides a foundation for further study of the functions of AcGRF genes and the traits they regulate.

背景：菠萝是凤梨科（Bromeliaceae）中唯一实现商业化种植的果品作物，兼具重要的农业、工业、经济与观赏价值。生长调节因子（growth-regulating factor, GRF）蛋白是一类在种子植物（embryophytes）中演化而来的重要转录因子。该类蛋白包含两个保守结构域：QLQ（Gln、Leu、Gln）与WRC（Trp、Arg、Cys），可调控植物生长与胁迫响应的多个方面，包括花器官发育、叶片生长及激素应答。目前已有多个植物物种的GRF家族得到系统鉴定，但针对菠萝及其他凤梨科植物的该家族研究却寥寥无几。
主要研究发现：本研究在菠萝中鉴定出8个GRF转录因子基因，经系统发育分析将其划分为5个亚家族（I、III、IV、V、VI）。片段重复似乎是菠萝GRF（AcGRF）家族扩张的主要驱动因素，且该家族在演化过程中经历了强烈的纯化选择。相较于其他基因家族，GRF家族的基因结构保守性相对较低。启动子顺式作用元件分析表明，AcGRF基因广泛参与植物生长发育过程。转录组数据与实时荧光定量PCR（qRT-PCR）结果显示，除AcGRF5外，其余AcGRF基因均在花器官发育早期偏好表达，且AcGRF2在胚珠中高表达。赤霉素处理可显著诱导AcGRF7/8的表达，提示这两个基因可能参与赤霉素促进菠萝果实膨大的分子调控通路。
结论：AcGRF蛋白似乎在花器官发育调控及赤霉素响应中发挥作用。本研究报道的相关信息为后续深入解析AcGRF基因的功能及其调控的性状提供了坚实的研究基础。