Abstract:

【Objective】 Fatty acid desaturase（FAD）is a key enzyme that catalyzes the synthesis of unsaturated fatty acids in plants, and it plays an important role in plant growth and development and response to adversity stress. This work aims to identify the tomato（Solanum lycopersi）SlFAD gene family and provide a theoretical basis for the study of tomato SlFAD gene family function and genetic improvement. 【Method】 Bioinformatics was used to identify the members of its gene family, and to study its physical and chemical properties, gene structure, phylogenetic tree and expression patterns. 【Result】 The total of 26 SlFAD genes were identified in the tomato genome, which can be divided into 4 sub-families. The analysis of physical and chemical properties showed that the number of amino acids of SlFAD protein was 119-912, the molecular weight was 13 288.27-102 522.25 Da. The SlFAD protein mainly existed in the nature of alkaline protein, and most of the members of the SlFAD family were stable proteins and hydrophilic proteins. Subcellular localization predicted that the members of the SlFAD gene family mainly were located in the endoplasmic reticulum. Genetic feature analysis showed that the members of the same subfamily hadsimilar genetic structure and conservative sequence. The analysis of cis-acting elements in the promotor showed that the largest number of components was related to light response and hormone response. Chromosome positioning revealed that 26 members of the SlFAD family were distributed on 10 chromosomes, and the largest number of members on chromosome 6 and 12. Secondary structure prediction demonstrated that 26 members of the SlFADs family were alpha-spiral and β-turning angle were the main ones. Transcriptome data and RT-qPCR analysis showed that the SlFAD1, SlFAD4 and SlFAD18 genes were highly expressed in mature anthers, and SlFAD23 was highly expressed in the root tip, indicating SlFAD1, SlFAD4 and SlFAD18 participated in the anther development, SlFAD23 participated in the root tip development. Under low-temperature stress, the expressions of SlFAD6 and SlFAD21 were inhibited, indicating that SlFAD6 and SlFAD21 might be related to low-temperature response, SlFAD1 and SlFAD14 at the beginning of low-temperature stress. The period significantly increased and then inhibited, indicating that the gene played an important role in the early stage of low-temperature stress. 【Conclusion】 The SlFAD gene family plays an important role in the growth and development of tomato roots, leaves, anthers and low-temperature stress.

Key words: Solanum lycopersicum, fatty acid dehydrogenase, FAD gene family, bioinformatics, expression analysis