Table_4_Genome-wide identification and expression analysis of AUX/LAX family genes in Chinese hickory (Carya cathayensis Sarg.) Under various abiotic stresses and grafting.docx

Auxin is essential for regulating plant growth and development as well as the response of plants to abiotic stresses. AUX/LAX proteins are auxin influx transporters belonging to the amino acid permease family of proton-driven transporters, and are involved in the transport of indole-3-acetic acid (IAA). However, how AUX/LAX genes respond to abiotic stresses in Chinese hickory is less studied. For the first time identification, structural characteristics as well as gene expression analysis of the AUX/LAX gene family in Chinese hickory were conducted by using techniques of gene cloning and real-time fluorescent quantitative PCR. Eight CcAUX/LAXs were identified in Chinese hickory, all of which had the conserved structural characteristics of AUX/LAXs. CcAUX/LAXs were most closely related to their homologous proteins in Populus trichocarpa , which was in consistence with their common taxonomic character of woody trees. CcAUX/LAXs exhibited different expression profiles in different tissues, indicating their varying roles during growth and development. A number of light-, hormone-, and abiotic stress responsive cis-acting regulatory elements were detected on the promoters of CcAUX/LAX genes. CcAUX/LAX genes responded differently to drought and salt stress treatments to varying degrees. Furthermore, CcAUX/LAX genes exhibited complex expression changes during Chinese hickory grafting. These findings not only provide a valuable resource for further functional validation of CcAUX/LAXs, but also contribute to a better understanding of their potential regulatory functions during grafting and abiotic stress treatments in Chinese hickory.

生长素（Auxin）在调控植物生长发育以及植物响应非生物胁迫过程中发挥着至关重要的作用。AUX/LAX蛋白属于质子驱动转运蛋白类的氨基酸通透酶家族，是生长素输入转运蛋白，参与吲哚-3-乙酸（indole-3-acetic acid, IAA）的转运过程。然而，目前对于中国山核桃中AUX/LAX基因如何响应非生物胁迫的研究尚少。本研究首次通过基因克隆与实时荧光定量PCR（real-time fluorescent quantitative PCR）技术，对中国山核桃的AUX/LAX基因家族开展了鉴定、结构特征分析以及基因表达模式研究。本研究在中国山核桃中鉴定得到8个CcAUX/LAX基因，所有基因均具备AUX/LAX家族保守的结构特征。CcAUX/LAX蛋白与毛果杨（Populus trichocarpa）的同源蛋白亲缘关系最近，这与其均为木本植物的分类学特征相符。CcAUX/LAX基因在不同组织中呈现出各异的表达谱，表明其在山核桃生长发育过程中发挥着不同的功能。在CcAUX/LAX基因的启动子区域，检测到大量响应光、激素以及非生物胁迫的顺式作用调控元件。CcAUX/LAX基因在干旱与盐胁迫处理下呈现出不同程度的差异化响应。此外，在中国山核桃嫁接过程中，CcAUX/LAX基因的表达呈现出复杂的动态变化。本研究结果不仅为后续CcAUX/LAX基因的功能验证提供了宝贵的研究资源，也有助于更深入地理解其在中国山核桃嫁接以及非生物胁迫处理过程中的潜在调控功能。