关键词: 烟粉虱, 脂肪酸延长酶, 基因家族, 生物信息学, 实时荧光定量PCR

Abstract:

【Objective】The host adaptability of Bemisia tabaci is closely associated with the plasticity of its lipid metabolism, particularly fatty acid metabolism. Fatty acid elongases (ELOs) are key regulatory components in fatty acid biosynthesis and modification. A comprehensive characterization of the ELO gene family in B. tabaci will contribute to elucidate the metabolic mechanisms underlying its nutritional adaptation, growth, and reproduction, and to identify novel target gene resources for sustainable green pest management strategies.【Method】Based on the B. tabaci MED genome and ELO sequences from other insects, ELO genes in B. tabaci were identified through multiple sequence alignment, 22 BtELO coding sequences were amplified and cloned using RT-PCR. Bioinformatics analyses were conducted to determine gene structure and protein physicochemical properties, and a maximum-likelihood phylogenetic tree was constructed to examine the evolutionary relationships between BtELOs and ELO genes from other Hemipteran insects. The temporal and spatial expression patterns of BtELOs in different developmental stages (egg, 1st-4th instar nymphs, and adults) and in various adult tissues (head, thorax, and abdomen) were analyzed using quantitative real-time PCR (qRT-PCR).【Result】A total of 22 BtELOs CDS were successfully identified and cloned, ranging from 714 to 1 296 bp. These genes, located on 10 genomic SCAFFOLDs, were sequentially designated BtELO1 through BtELO22 based on their linear arrangement. The encoded proteins, comprising 237 to 431 amino acids, are generally hydrophobic, contain 6-7 transmembrane domains, and are predicted to localize in the endoplasmic reticulum. Sequence alignment and phylogenetic analyses revealed that BtELO proteins possess the typical ELO conserved domain and histidine cluster (HXXHH). The sequence similarity among BtELO family members was as high as 76%. The BtELOs were grouped into 7 major evolutionary clades with clear phylogenetic clustering patterns, indicating conserved evolutionary relationships, with some genes forming independent clades indicative of gene duplication events. Spatiotemporal expression profiling revealed that the expression of BtELOs exhibited clear stage- and tissue-specific patterns in B. tabaci, indicating that these genes may perform diverse biological functions in this species.【Conclusion】The 22 BtELOs identified in B. tabaci contain the typical elongase domain and the conserved HXXHH motif. All BtELOs are expressed in various developmental stages and tissues of B. tabaci. Several genes exhibit high expression in eggs and adult abdomens, suggesting potential roles in reproductive processes, whereas those highly expressed during the nymphal stages may be associated with growth, development, and molting.

Key words: Bemisia tabaci, fatty acid elongase (ELO), gene family, bioinformatics, qRT-PCR