摘要
全基因组关联分析(genome-wide association analysis,GWAS)是以高通量测序技术为基础,结合生物信息学和统计学方法,在全基因组水平上鉴定调控复杂性状的基因变异,是研究复杂农艺性状和遗传变异最有力和最有效的研究方法,其核心是研究遗传变异和目标性状之间的关联。GWAS研究检测到的关联位点一般很少,而且关联的位点仅能解释很少一部分性状变异。本文介绍了影响GWAS的主要因素,总结了GWAS在茶叶饮料消费、茶树重要农艺性状、茶叶品质和茶树群体结构研究中取得的一系列进展,提出了茶树GWAS研究中遇到的问题和未来的发展方向。
茶树(Camellia sinensis(L.)O.Kuntze)是重要的经济作物,具有数千年种植历史。全球超50个国家种植茶树,茶饮料深受消费者的喜
GWAS是一种基于连锁不平衡(linkage disequilibrium,LD)原理的分析方法,用于检测遗传变异和群体样本特征之间的联系,挖掘与目标性状相关联的遗传位点,为作物目标性状的改良提供基础,为分子育种提供新的研究路径与思
虽然GWAS在人类、动物和植物中已经被广泛应用,但是仍然有许多因素限制着GWAS的发展。GWAS研究检测到的关联位点一般很少,而且关联的位点仅能解释很少一部分性状变异。而未能检测到的遗传关联位点占有很大一部分比
1)结构变异。一般情况下,复杂性状的差异不是由一个位点的遗传变异引起,还可能受到结构变异的影响,如拷贝数变异(copy number variations,CNV
2)上位效应和环境效应。据统计,大多数GWAS研究没有关注不同遗传变异位点之间的相互作用以及遗传位点和环境之间的相互作
复杂性状不仅受到基因位点之间互作的影响同时也会受到不同环境条件的影响,在GWAS研究中未能通过遗传相关性解释的关联位性点可能是由于没有考虑基因和环境之间的互作。因此,需要结合样本大小、试验设计和基因型等众多因素来考虑基因与环境之间的互作对于GWAS研究的影响。在GWAS的相关研究中,虽然已经提出有关研究基因与环境之间互作的研究方法和实验方案,并取得一定的成
3)稀有等位频率。GWAS鉴定关联性位点是以等位基因频率(allel frequency)为基础,低频率的等位基因遗传变异对研究群体的影响较小,但还有部分低频率的等位基因对性状有很大的影
QTL和GWAS都是基于群体的遗传图谱来研究群体间个体的复杂性状,二者有许多异同点。数量性状位点(QTL)定位的连锁分析是GWAS等关联研究的直接先驱,这就意味着GWAS比QTL研究结果更为精确。连锁图谱不是将个体组合成一个不同的GWAS面板,而是研究具有已知关系的个
尽管连锁分析是解析复杂性状的主要方法,但关联研究的潜在价值也受到了重视。与连锁分析相比,关联分析的优势包括不需要进行杂交实
GWAS一个明显的缺陷是会出现较高的假阳性,即把不与性状相关联的位点划分到关联位点内,使结果中包含有与研究目的不相关的位点。群体结构和个体间的亲缘关系都会导致高假阳性率,降低假阳性的方法包括调整多重测试校正的限制错误发现率、调整每个标记的P值以及使用合适的结构化关联方
茶作为三大无酒精饮料之一,具有良好的养生保健功能,其饮用价值一直是研究的热点。对于茶叶消费习惯的GWAS研究是社会学研究的热点。虽然有较多关于茶叶消费习惯的GWAS研究,但是并没有鉴定出与茶叶饮用习惯相关的遗传位点。Taylor
人类健康问题一直是研究者关注的重心,由于茶有其独特的养身保健功能,所以也一直成为医药和营养研究关注的热点。Malik
1)GWAS 在茶树树型和叶片表型研究中的应用。茶树主要生长在热带、亚热带,不同地区、不同品种的茶树树型和叶片表型差异很大,即使是生长在同一地区的不同茶树品种的叶片表型差异也较大。茶树的树型主要分为灌木、小乔木和乔木,树姿主要分为直立、半开张和开张,不同地区、不同品种的茶树树型和树姿有明显的差异,因此,树型和树姿可作为茶树分类和品种选育的重要依据。Lu
茶树叶片不仅是重要的营养器官也是茶叶产品的原材料,具有重要的经济价值。茶叶面积的大小对茶叶产量具有重要影响,以黑茶、乌龙茶、红茶以及抹茶尤为突
茶叶叶片形状具有较强的遗传多样性,不同品种的茶树叶片形状差异大,即使是同一品种的茶树其叶片形状也会有所不同。茶叶叶片特性是决定茶叶品质的重要因素,是育种选择的重要指标。Zhang
2)GWAS在茶树春芽萌发时间研究中的应用。茶树春梢是茶叶生产加工的直接原材料,叶片是进行光合作用制造有机营养物质的器官,其着生于新
茶叶品质一直是茶叶研究的重点。茶叶的品质由茶叶中多种生化成分共同决定,其中对茶叶品质影响显著的主要是次生代谢物,如儿茶素、茶多酚和咖啡碱等。Yamashita
目前很少同时将茶树表型性状、茶叶品质成分与茶树进行全基因组关联分析,但Hazra
由于茶氨酸、咖啡碱和儿茶素对茶品质及其生理功能有重要影响,其合成和调控相关基因的鉴定对于了解茶叶品质成分的合成和调控途径、培育高品质的茶树具有重要意义。Fang
游离氨基酸(尤其是茶氨酸)是茶叶中最主要的化学成分之一,有助于提高茶的口感、功能和质量。人工杂交能够有效选育出高氨基酸含量且综合性状优良的茶树新种质。Huang
传统的基于表型评价的育种方法存在茶树世代长、表型测量准确性差,无法在茶树达到生理成熟之前对茶叶品质和产量进行评估等问题。然而,传统的茶树育种方法仍处于主导地
成功的GWAS需要来自群体的全面而又准确的基因组和表型数据。虽然有多种高通量DNA测序方法可用于生成基因组数据,但生成高质量表型数据的技术却远远落后于基因组测序技术。传统的植物表型测量方法大多依赖于人工,具有费力、耗时及不准确等缺点,不利于从群体中快速而准确地获取表型数据。高通量表型技术克服了传统方法的上述缺点,已成为评价植物表型的有力工
生物/非生物胁迫是影响植物产量、品质和生长发育的主要因素,水稻、玉米、小麦等禾本科植物和梨、桃、苹果、茶树等木本植物都将生物/非生物胁迫作为研究的热点。基于病虫害的GWAS最初是在拟南芥、水稻、小麦等模式作物中开展,因木本植物基因组问世比较晚,木本植物的GWAS也进展缓慢。随着木本植物基因组的公布,对木本植物基于生物/非生物胁迫的GWAS也在不断发展,如在苹果、梨、橙子和杏等木本植物中开展了基于苹果斑枯病、白粉病、病原菌抗性和低温胁迫等的GWA
一般来说,表型性状的变异有限,而大量代谢物的含量存在巨大的差异。GWAS鉴定的作物表型性状QTL往往具有中或低等效
参考文献 References
叶乃兴.茶学研究法[M].北京:中国农业出版社,2011.YE N X.Research methods of tea science[M].Beijing:China Agriculture Press,2011 (in Chinese). [百度学术]
ZHANG X T,CHEN S,SHI L Q,et al.Haplotype-resolved genome assembly provides insights into evolutionary history of the tea plant Camellia sinensis[J/OL].Nature genetics,2021,53 (6):1250[2022-03-07].https://doi.org/10.1038/s41588-021-00895-y. [百度学术]
LIN X H,SUN D W.Recent developments in vibrational spectroscopic techniques for tea quality and safety analyses[J].Trends in food science & technology,2020,104:163-176. [百度学术]
ZHANG L,HO C T,ZHOU J,et al.Chemistry and biological activities of processed Camellia sinensis teas:a comprehensive review[J].Comprehensive reviews in food science and food safety,2019,18(5):1474-1495. [百度学术]
XIA E H,TONG W,WU Q,et al.Tea plant genomics:achievements,challenges and perspectives[J/OL].Horticulture research,2020,7 (1):7 [2022-03-07].https://doi.org/10.1038/s41438-019-0225-4. [百度学术]
XIA E H,ZHANG H B,SHENG J,et al.The tea plant genome provides insights into tea flavor and independent evolution of caffeine biosynthesis[J].Molecular plant,2017,10(6):866-877. [百度学术]
CHEN J D,ZHENG C M,JIAN Q J,et al.The chromosome-scale genome reveals the evolution and diversification after the recent tetraploidization event in tea plant[J].Horticulture research,2020,7 (1):63-73. [百度学术]
XIA E H,TONG W,HOU Y,et al.The reference genome of tea plant and resequencing of 81 diverse accessions provide insights into its genome evolution and adaptation[J].Molecular plant,2020,13(7):1013-1026. [百度学术]
ZHANG Q J,LI W,LI K,et al.The chromosome-level reference genome of tea tree unveils recent bursts of non-autonomous LTR retrotransposons in driving genome size evolution[J].Molecular plant,2020,13(7):935-938. [百度学术]
WANG X C,FENG H,CHANG Y X,et al.Population sequencing enhances understanding of tea plant evolution[J/OL].Nature communications,2020,11 (1):4447 [2022-03-07].https://doi.org/10.1038 /s41467-020-18228-8. [百度学术]
ZHANG W Y,ZHANG Y J,QIU H J,et al.Genome assembly of wild tea tree dasz reveals pedigree and selection history of tea varieties[J/OL].Nature communications,2020,11 (1):3719 [2022-03-07].https://doi.org/10.1038/s41467-020-17498-6. [百度学术]
WANG P J,YU J X,JIN S,et al.Genetic basis of high aroma and stress tolerance in the oolong tea cultivar genome[J/OL].Horticulture research,2021,8 (1):107 [2022-03-07].https://doi.org/10.1038/s41438-021-00542-x. [百度学术]
ERSOZ E S,YU H M,BUCKLER E S.Applications of linkage disequilibrium and association mapping in crop plants[M].Dordrecht:Springer ,2008:97-119. [百度学术]
赵振卿,顾宏辉,盛小光,等.作物数量性状位点研究进展及其育种应用[J].核农学报,2014,28(9):1615-1624.ZHAO Z Q,GU H H,SHENG X G,et al.Advances and applications in crop quantitative trait locus[J].Journal of nuclear agricultural sciences,2014,28(9):1615-1624(in Chinese with English abstract). [百度学术]
FREEMAN J L,PERRY G H,FEUK L,et al.Copy number variation:new insights in genome diversity[J].Genome research,2006,16(8):949-961. [百度学术]
KORTE A,FARLOW A.The advantages and limitations of trait analysis with GWAS:a review[J].Plant methods,2013,9 (4):749-764. [百度学术]
ZUK O,HECHTER E,SUNYAEV S R,et al.The mystery of missing heritability:genetic interactions create phantom heritability[J].PNAS,2012,109(4):1193-1198. [百度学术]
WEI W H,HEMANI G,HALEY C S.Detecting epistasis in human complex traits[J].Nature reviews genetics,2014,15 (11):722-733. [百度学术]
WINHAM S J,BIERNACKA J M.Gene-environment interactions in genome-wide association studies:current approaches and new directions[J].Journal of child psychology and psychiatry,2013,54(10):1120-1134. [百度学术]
THOMAS D.Gene-environment interactions in human diseases[J].Nature reviews genetics,2005,6 (4):287-298. [百度学术]
MYLES S,PEIFFER J,BROWN P J,et al.Association mapping:critical considerations shift from genotyping to experimental design[J].The plant cell,2009,21(8):2194-2202. [百度学术]
GIBSON G.Rare and common variants:twenty arguments[J].Nature reviews genetics,2012,13 (2):135-145. [百度学术]
HAZELETT D J,COETZEE S G,COETZEE G A.A rare variant,which destroys a FoxA1 site at 8q24,is associated with prostate cancer risk[J].Cell cycle,2013,12(2):379-380. [百度学术]
GOURAB D,YIP W,IULIANA I,et al.Rare variant analysis for family-based design[J/OL].PLoS One,2017,8 (1):e48495 [2022-03-07].https://doi.org/10.1371/journal.pone.0048495. [百度学术]
CORTES L T,ZHANG Z W,YU J M.Status and prospects of genome-wide association studies in plants[J/OL].Plant genome,2021,14 (1):e20077 [2022-03-07].https://doi.org/10.1002/tpg2.20077. [百度学术]
PATERSON A H,LANDER E S,HEWITT J D,et al.Resolution of quantitative traits into mendelian factors by using a complete linkage map of restriction fragment length polymorphisms[J].Nature,1988,335 (6192):721-726. [百度学术]
LANDER E,KRUGLYAK L.Genetic dissection of complex traits - guidelines for interpreting and reporting linkage results[J].Nature genetics,1995,11 (3):241-247. [百度学术]
THORNSBERRY J M,GOODMAN M M,DOEBLEY J,et al.Dwarf8 polymorphisms associate with variation in flowering time[J].Nature genetics,2001,28 (3):286-289. [百度学术]
YU J M,PRESSOIR G,BRIGGS W H,et al.A unified mixed-model method for association mapping that accounts for multiple levels of relatedness[J].Nature genetics,2006,38 (2):203-208. [百度学术]
KLASEN J R,BARBEZ E,MEIER L,et al.A multi-marker association method for genome-wide association studies without the need for population structure correction[J/OL].Nature communications,2016,7:13299 [2022-03-07].https://doi.org/10.1038/ncomms13299. [百度学术]
KANG H M,ZAITLEN N A,WADE C M,et al.Efficient control of population structure in model organism association mapping[J].Genetics,2008,178(3):1709-1723. [百度学术]
TAYLOR A E,DAVEY SMITH G,MUNAFÒ M R.Associations of coffee genetic risk scores with consumption of coffee,tea and other beverages in the UK Biobank[J].Addiction,2018,113(1):148-157. [百度学术]
CORNELIS M C.Genetic determinants of beverage consumption:implications for nutrition and health[J].Advances in food and nutrition research,2019,89:1-52. [百度学术]
ZHONG V W,KUANG A L,DANNING R D,et al.A genome-wide association study of bitter and sweet beverage consumption[J].Human molecular genetics,2019,28(14):2449-2457. [百度学术]
FURUKAWA K,IGARASHI M,JIA H,et al.A genome-wide association study identifies the association between the 12q24 locus and black tea consumption in Japanese populations[J/OL].Nutrients,2020,12(10):3182 [2022-03-07].https://doi.org/10.3390/nu12103182. [百度学术]
MATOBA N,AKIYAMA M,ISHIGAKI K,et al.GWAS of 165,084 Japanese individuals identified nine loci associated with dietary habits[J].Nature human behaviour,2020,4 (3):308-316. [百度学术]
COLE J B,FLOREZ J C,HIRSCHHORN J N.Comprehensive genomic analysis of dietary habits in UK Biobank identifies hundreds of genetic associations[J/OL].Nature communications,2020,11 (1) :1467 [2022-03-07].https://doi.org/10.1038/s41467-020-15193-0. [百度学术]
MALIK M A,UMAR M,GUPTA U,et al.Phospholipase C Epsilon 1 (PLCE1 rs2274223A>G,rs3765524C>T and rs7922612C>T) polymorphisms and esophageal cancer risk in the Kashmir Valley[J].Asian Pacific journal of cancer prevention:APJCP,2014,15(10):4319-4323. [百度学术]
LU L T,CHEN H F,WANG X J,et al.genome-level diversification of eight ancient tea populations in the guizhou and yunnan regions identifies candidate genes for core agronomic traits[J/OL].Horticulture research,2021,8 (1):190 [2022-03-07].https://doi.org/10.1038/s41438-021-00617-9. [百度学术]
AN Y L,MI X Z,ZHAO S Q,et al.Revealing distinctions in genetic diversity and adaptive evolution between two varieties of Camellia sinensis by whole-genome resequencing[J/OL].Frontiers in plant science,2020,11:603819[2022-03-07].https://doi.org/10.3389/fpls.2020.603819. [百度学术]
TAN L Q,WANG L Y,XU L Y,et al.SSR-based genetic mapping and QTL analysis for timing of spring bud flush,young shoot color,and mature leaf size in tea plant (Camellia sinensis)[J].Tree genetics & genomes,2016,12(3):1-13. [百度学术]
ZHANG F,TIAN W L,CEN L,et al.Population structure analysis and genome-wide association study of tea (Camellia Sinensis (L.) Kuntze) germplasm in Qiannan,China,based on SLAF-Seq technology[J].Phyton-international journal of experimental botany,2022,91 (4):791-809. [百度学术]
史春彦,张前东,张晓平,等.济南市长清区茶树种植适宜性农业区划[J].山东农业科学,2016,48(10):81-85.SHI C Y,ZHANG Q D,ZHANG X P,et al.Suitable agricultural regionalization for tea planting in Changqing district of Ji’nan City[J].Shandong agricultural sciences,2016,48(10):81-85(in Chinese with English abstract). [百度学术]
WANG R J,GAO X F,YANG J,et al.Genome-wide association study to identify favorable SNP allelic variations and candidate genes that control the timing of spring bud flush of tea (Camellia sinensis) using SLAF-seq[J].Journal of agricultural and food chemistry,2019,67(37):10380-10391. [百度学术]
YAMASHITA H, UCHIDA T, TANAKA Y, et al. Genomic predictions and genome-wide association studies based on RAD-seq of quality-related metabolites for the genomics-assisted breeding of tea plants[J]. Scientific reports, 2020, 10 (1): 17480 [2022-03-07].https://doi.org/10.1038/s41598-020-74623-7. [百度学术]
HAZRA A,KUMAR R,SENGUPTA C,et al.Genome-wide SNP discovery from Darjeeling tea cultivars - their functional impacts and application toward population structure and trait associations[J].Genomics,2021,113(1):66-78. [百度学术]
FANG K X,XIA Z Q,LI H J,et al.Genome-wide association analysis identified molecular markers associated with important tea flavor-related metabolites[J/OL].Horticulture research,2021,8 (1):42 [2022-03-07].https://doi.org/10.1038/s41438-021-00477-3. [百度学术]
HUANG R,WANG J Y,YAO M Z,et al.Qe trait loci mapping for free amino acid content using an albino population and SuantitativNP markers provides insight into the genetic improvement of tea plants[J/OL].Horticulture research,2022,9:uhab029[2022-03-07].https://doi.org/10.1093/hr/uhab029. [百度学术]
IWATA H,MINAMIKAWA M F,KAJIYA-KANEGAE H,et al.Genomics-assisted breeding in fruit trees[J].Breeding science,2016,66(1):100-115. [百度学术]
XIAO Q L,BAI X L,ZHANG C,et al.Advanced high-throughput plant phenotyping techniques for genome-wide association studies:a review[J].Journal of advanced research,2022,35:215-230. [百度学术]
YANG W N,FENG H,ZHANG X H,et al.Crop phenomics and high-throughput phenotyping:past decades,current challenges,and future perspectives[J].Molecular plant,2020,13(2):187-214. [百度学术]
JIANG L B,SUN L D,YE M X,et al.Functional mapping of N deficiency-induced response in wheat yield-component traits by implementing high-throughput phenotyping[J].The plant journal,2019,97(6):1105-1119. [百度学术]
RASHEED A,XIA X C,OGBONNAYA F,et al.Genome-wide association for grain morphology in synthetic hexaploid wheats using digital imaging analysis[J/OL].BMC plant biology,2014,14:128[2022-03-07].https://doi.org/10.1186/1471-2229-14-128. [百度学术]
SHAKOOR N,LEE S,MOCKLER T C.High throughput phenotyping to accelerate crop breeding and monitoring of diseases in the field[J].Current opinion in plant biology,2017,38:184-192. [百度学术]
NOH J,DO Y S,KIM G H,et al.A genome-wide association study for the detection of genes related to apple Marssonina Blotch disease resistance in apples[J/OL].Scientia horticulturae,2020,262:108986[2022-03-07].https://doi.org/10.1016/j.scienta.2019.108986. [百度学术]
PENG Z,BREDESON J V,WU G A,et al.A chromosome-scale reference genome of trifoliate orange (Poncirus trifoliata) provides insights into disease resistance,cold tolerance and genome evolution in Citrus[J].The plant journal,2020,104(5):1215-1232. [百度学术]
HUANG X,ZHAO Y,WEI X,et al.Genome-wide association study of flowering time and grain yield traits in a worldwide collection of rice germplasm[J].Nature genetics,2012,44:32-39. [百度学术]
CHEN W,WANG W S,PENG M,et al.Comparative and parallel genome-wide association studies for metabolic and agronomic traits in cereals[J/OL].Nature communications,2016,7:12767 [2022-03-07].https://doi.org/10.1038/ncomms12767. [百度学术]
ZHU G T,WANG S C,HUANG Z J,et al.Rewiring of the fruit metabolome in tomato breeding[J].Cell,2018,172(1/2):249-261. [百度学术]
LEE T,KIM H,LEE I.Network-assisted crop systems genetics:network inference and integrative analysis[J].Current opinion in plant biology,2015,24:61-70 [百度学术]