【摘要】 【目的】为研究无患子科SMXL家族的生物学特性提供理论参考，深入探究该基因家族在无患子科植物非生物胁迫响应中的调控机制。【方法】基于模式植物拟南芥SMXL家族的氨基酸序列，利用TBtools对龙眼、红毛丹、无患子和荔枝的SMXL家族成员进行全基因组鉴定，Expasy、MEGA11等软件用于4种无患子科植物的进化和功能分析，同时利用龙眼转录组数据进行体胚发生早期阶段的表达分析。【结果】4种无患子科植物共鉴定出48个SMXL家族成员，其中龙眼11个、红毛丹11个、无患子9个以及荔枝17个。依据拟南芥SMXL家族成员的分类，将4种无患子科SMXL家族成员分为5个亚族且亚细胞定位于叶绿体、细胞核、细胞质或线粒体。蛋白互作分析表明，无患子科SMXL家族成员可能与多种蛋白存在互作关系，主要分为两类：一种是与受到非生物胁迫时大量表达的热休克蛋白（HSPs）或CLPs互作；另一种是与独角金内酯受体蛋白D14、karrikins受体蛋白KAI2和调控SL信号传导途径的蛋白MAX2进行互作。启动子顺式作用元件分析表明，4种无患子科植物SMXL家族成员存在较多的光响应元件、抗氧化反应元件（ARE）和脱落酸响应元件（ABRE）等，推测该基因家族广泛参与非生物胁迫响应。此外，DlSMXL家族成员在龙眼体胚发生早期存在5种不同的表达模式，其中DlSMXL4基因家族成员在胚性愈伤组织（EC）、不完全胚性紧实结构（ICpEC）和球形胚（GE）阶段相较其他成员呈现较高表达。基于5-氮胞苷、PEG、SL、光、温度和各种激素处理龙眼EC时期转录组数据分析可知，龙眼DlSMXL5在干旱、GR24、黑暗和高温处理下表达量均明显增加，推测该成员能够通过响应植物激素和应激胁迫维持胚性愈伤组织形态。其次DlSMXL8在5-氮胞苷处理时表达上调，推测其可能参与DNA甲基化在龙眼体胚发生过程中发挥作用。【结论】4种无患子科植物SUPPRESSOR OF MAX2-LIKE(SMXL)家族除了在植物生长发育过程种发挥重要的作用，同时还广泛参与植物非生物胁迫调控过程。本研究结果为无患子科植物中SMXL的分类和生物学功能提供了理论依据，并为SMXL在龙眼早期体细胞胚胎发生中的功能验证提供了更好的认识。更多还原

【Abstract】 【Objective】To provide a theoretical reference for the study of the biological characterization of the SMXL family of Sapindaceae,and to delve into the regulatory mechanism of this gene family in the abiotic stress response of Sapindaceae plants. 【Method】Based on the amino acid sequences of the SMXL family of the model plant Arabidopsis thaliana,TBtools was used for genome-wide identification of SMXL family members from longan,rambutan, sapindus,and litchi. MEGA11 was used to construct the phylogenetic tree,and online software such as Expasy,WoLF PSORT,MEME,STRING,PlantCARE,etc. were used to predict the protein physicochemical properties,subcellular structural localization,conserved motifs,protein interactions,cis-acting elements,etc. respectively. Longan transcriptome data were also utilized for expression analysis in the early stages of somatic embryogenesis. 【Result】Forty-eight SMXL family members were identified in four Sapindaceae species,including 11 in longan,11 in rambutan,9 in sapindus,and 17 in litchi. According to the classification of the SMXL family of Arabidopsis thaliana,the SMXL family members in four Sapindaceae species could be divided into 5 subfamilies,and the subcells were located in chloroplasts,nuclei,cytoplasm or mitochondria. Protein interaction analyses showed that SMXL family members in Sapindaceae could interact with a variety of proteins,which were mainly classified into two categories:one with the heat shock proteins(HSP) or CLP,which were abundantly expressed when subjected to abiotic stress; the other interacted with the strigolactone receptor protein D14,the karrikin receptor protein KAI2,and the MAX2 protein,which regulated the SL signaling pathway. The results of the cis-element analysis showed that among the SMXL family members of the four Sapindaceae species,there were more lightresponsive elements,anaerobiosis-inducible elements(ARE),and abscisic acid-responsive elements(ABRE),etc. Therefore,it was hypothesized that the SMXL members were largely involved in the response to abiotic stress in Sapindaceae. Furthermore,there were five different expression profiles of the DlSMXL family during the early SE in longan,with the DlSMXL4 showing higher expression at embryogenic callus(EC),incomplete compact proembryogenic(ICpEC),and globular embryos(GE) stages compared with the other members. Based on analysis of transcriptomic data at longan EC treated with 5-azacytidine,PEG,SL,light,temperature,and various hormones,it could be seen that DlSMXL5 expression was significantly increased by drought,GR24,darkness,and high-temperature treatments. It is hypothesized that this member is capable of maintaining embryonic healing tissue morphology in response to phytohormones and stressful stresses. Secondly,DlSMXL8 was up-regulated after 5-azacytidine treatment,which might be involved in DNA methylation playing a role during somatic embryogenesis in longan. 【Conclusion】As well as playing a critical role in plant growth and development,the SMXL family of four Sapindaceae species is also widely implicated in the regulation of abiotic stress. Our results provide a theoretical basis for the classification and biological function of SMXLs in the Sapotaceae and give a better understanding of the functional validation of SMXLs in early somatic embryogenesis longan.更多还原