Abstract: Alfalfa (Medicago sativa) is an important leguminous forage that is widely cultivated all over the world. In this study,full-length transcriptome sequencing of a thrip-resistant alfalfa variety 'Caoyuan No.4’ was performed using the PacBio technology. A total of 35.10 Gb of clean data were generated,and 355 992 CCS Reads were obtained,including 238 454 full-length non-chimeric Reads (FLNC reads),which accounts for 40.46 %. A total of 11 271 alternative splicing (AS),32 102 SSR sites,11 514 lncRNA and 76 293 complete CDS sequences were identified. 83 008 transcripts were annotated in NR,COG,GO,KEGG,Swiss-Prot,and Pfam databases. Based on the transcriptome data,the expression of genes involved in flavonoid biosynthesis were analyzed by qRT-PCR,and it was found that the expression of flavonoid biosynthesis genes including DFR,FLS,F3H,CYP93B2_16,C3'H,CHI,CYP75B1,HCT and ANR were all significantly increased after thrips feeding for 7 d,and then decreased sharply. However,the expression level of ANS gene was increased gradually with the prolongation of thrips feeding. These results showed that the genes involved in flavonoid biosynthesis were related to the response of alfalfa to thrips feeding,and most of the genes were involved in the early defense response,but ANS may be involved in the late defense response.

Key words: Alfalfa, Full-length transcriptome, Flavonoids, Thrips

摘要： 紫花苜蓿(Medicago sativa)是国内外广泛栽培的重要豆科牧草。本研究利用PacBio技术对抗蓟马苜蓿品种'草原4号’进行全长转录组测序，共获得35.10 Gb的clean data，355 992条环形一致性序列(CCS Reads)，其中全长非嵌合序列(FLNC Reads)238 454个，占40.46%，共鉴定出11 271个可变剪切事件(AS)，32 102个SSR位点，11 514个lncRNA和76 293个完整的CDS序列。在NR、COG、GO、KEGG、Swiss-Prot和Pfam数据库中注释了83 008个转录本。基于转录组数据，对参与类黄酮生物合成基因进行qRT-PCR检测，分析发现除了ANS外，类黄酮生物合成基因DFR，FLS，F3H，CYP93B2_16，C3'H，CHI，CYP75B1，HCT，ANR的表达量在蓟马取食7天后均显著上调，之后急剧下降(P≤0.05)；ANS基因则随着蓟马取食时间的延长表达量逐渐上升。研究结果表明类黄酮生物合成基因参与苜蓿响应蓟马取食过程，且大部分基因参与早期防御反应，ANS可能参与晚期防御反应。

关键词: 紫花苜蓿, 全长转录组, 类黄酮, 蓟马