2021年9月21日 星期二
薯蓣茎生珠芽发生相关的转录组和 PEBP家族基因表达特性分析
Analyses on transcriptome and PEBP family gene expression characteristics related to stem bulbil genesis of Dioscorea polystachya
2021年 第30卷 第3期 页码[8-19]    下载全文[10.5MB]  
摘要

以薯蓣(Dioscorea polystachya Turcz.)的具茎生珠芽品种‘铁棍山药’(‘Tiegun’)和无茎生珠芽品种‘花籽山药’(‘Huazi’)为研究对象,采集‘铁棍山药’具茎生珠芽、茎基部无茎生珠芽和茎上部无茎生珠芽的叶腋部位以及‘花籽山药’的叶腋部位4组样品进行转录组测序,并以‘铁棍山药’不同发育期茎生珠芽的叶腋部位为样品进行qRT-PCR分析,以期明确与薯蓣茎生珠芽发生相关的调控基因。结果显示:从2个品种不同部位的4组样品中共获得77 981个All-unigenes,长度主要集中于300~3 000 bp,占总量的99.44%;All-unigenes的平均长度为1 050 bp,N50值为1 764 bp,GC含量为42.66%;转录组unigenes与油棕(Elaeis guineensis Jacq.)和海枣(Phoenix dactylifera Linn.)的同源性较高。对具茎生珠芽叶腋样品与3组无茎生珠芽叶腋样品的差异unigenes进行功能注释和表达量比较。结果显示:经过GO注释分析,3组转录组分别有6 098、8 840和9 141个差异unigenes注释在细胞组分、分子功能和生物过程3大类43个亚类中,其中,注释在代谢过程亚类的差异unigenes数分别占对应注释unigenes总数的10.6%、10.5%和10.7%;3组转录组分别有11 182、13 552和15 918个差异unigenes注释在KEGG代谢通路,且主要集中在代谢和遗传信息处理;表达量均上调的unigenes有3 531个,表达量均下调的unigenes有1 084个;在具茎生珠芽叶腋部位中特异性表达的unigenes有235个,而在无茎生珠芽叶腋部位中均特异性表达的unigene仅1个。从转录组中共鉴定出11个PEBP家族成员,且在系统演化树上这些PEBP家族基因主要分布在TFL1-like和FT-like 分支上,其中位于TFL1-like分支的Unigene40804_All与拟南芥〔Arabidopsis thaliana (Linn.) Heynh.〕中已知功能的TFL1基因高度同源,被命名为DpTFL1,且DpTFL1基因仅在‘铁棍山药’具茎生珠芽的叶腋部位表达。qRT-PCR分析结果显示:随‘铁棍山药’茎生珠芽发育,DpTFL1基因的表达量逐渐升高,在发育成熟期达到最高。综合分析结果表明:与淀粉合成相关的SUS等基因以及与激素和糖代谢相关的基因可能参与‘铁棍山药’茎生珠芽发育的调控;DpTFL1基因在‘铁棍山药’具茎生珠芽的叶腋部位特异性表达,其可能与薯蓣茎生珠芽发生有关。

Abstract

Taking cultivar ‘Tiegun’ (with stem bulbils) and ‘Huazi’ (without stem bulbil) of Dioscorea polystachya Turcz. as research objects, transcriptome sequencing was performed for 4 groups of samples namely leaf axils of ‘Tiegun’ with stem bulbils, without stem bulbil on base part of stem, and without stem bulbil on upper part of stem, and leaf axils of ‘Huazi’, and qRTPCR analysis was conducted using the leaf axils of stem bulbils of ‘Tiegun’ at different development stages as samples to clarify the regulation genes related to the stem bulbil genesis of D. polystachya. The results show that 77 981 All-unigenes are obtained in total from 4 groups of samples from different parts of 2 cultivars, and their length are mainly concentrated within 300-3 000 bp, accounting for 99.44% of the total amount; the average length of All-unigenes is 1 050 bp, the N50 value is 1 764 bp, and the GC content is 42.66%; the unigenes in transcriptome are highly homologous to Elaeis guineensis Jacq. and Phoenix dactylifera Linn. Functional annotation and expression comparison were conducted for differential unigenes between leaf axil sample with stem bulbils and 3 groups of leaf axil samples without stem bulbil. The results show that after GO annotation analysis, 6 098, 8 840, and 9 141 differential unigenes in 3 groups of transcriptomes are annotated into 43 subcategories of 3 categories (cellular component, molecular function, and biological process), in which, the number of unigenes annotated in subcategory of metabolic process accounts for 10.6%, 10.5%, and 10.7% of total number of corresponding annotated unigenes, respectively; there are 11 182, 13 552, and 15 918 differential unigenes in 3 groups of transcriptomes annotated in KEGG metabolic pathway, and are mainly concentrated in metabolism and genetic information processing; the number of upregulated unigenes is 3 531, and that of down-regulated unigenes is 1 084; there are 235 specifically expressed unigenes in leaf axils with stem bulbils, while there is only 1 unigene specifically expressed in all leaf axils without stem bulbil. In total, 11 PEBP family members are identified from transcriptome, and these PEBP family genes are mainly distributed on TFL1-like and FT-like branches of the phylogenetic tree, in which, Unigene40804_All located on TFL1like branch is highly homologous to TFL1 gene (known function) of Arabidopsis thaliana (Linn.) Heynh., named as DpTFL1, and DpTFL1 gene only expresses in leaf axils of ‘Tiegun’ with stem bulbils. The qRTPCR analysis result shows that with the development of stem bulbils of ‘Tiegun’, the expression of DpTFL1 gene gradually increases, and reaches the highest level at mature development stage. The comprehensive analysis result shows that genes related to starch synthesis such as SUS and genes related to hormone and carbohydrate metabolism may be involved in regulation of stem bulbil development of ‘Tiegun’; DpTFL1 gene is specifically expressed in leaf axils of ‘Tiegun’ with stem bulbils, and it may relate to stem bulbil genesis of D. polystachya.

关键词薯蓣; 茎生珠芽; 转录组; PEBP家族基因; TFL1-like; 相对表达量
Key wordsDioscorea polystachya Turcz.; stem bulbil; transcriptome; PEBP family gene; TFL1-like; relative expression
作者孙玲, 王月, 陈闽, 孙小芹, 杭悦宇, 张艳梅
所在单位江苏省中国科学院植物研究所(南京中山植物园), 江苏 南京 210014
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基金项目江苏省植物资源研究与利用重点实验室基金项目(SQ201404); 省属公益类科研院所自主科研项目(BM2018021-2)