Analysis Of Genetic Diversity And Application Potential Of Tobacco Germplasm Resources And Screening Of Core SSR Primers

As addictive adeconomic crop, tobacco occupies an important place in the national economy.In recent years,some problems exist in tobacco production,breeding research and application of SSR markers.foe example:unitary genetic background in main varieties, less local characteristics, slow progress of breeding research and lower selecting efficiency of SSR marker.This study discuss from three aspects include analysis of genetic diversity and application potential of tobacco germplasm resources, Screening of core SSR primers to provide reference to solve these problems.1. Analysis of genetic diversity of tobacco germplasm resourcesCultivated tobacco is divided into6types in China which includ flue-cured tobacco, sun-cured tobacco, burley tobacco, aromatic tobacco, air-cured tobacco, rustica tobacco, also including wild tobacco resources. The study use SSR marker to confirm the genetic distance of140tobacco germplasms includ these six types, analyze their phenotypic diversity of agronomic characters use morphological analyze method, the results are as following:1)According to genetic relationship140tobacco germplasm resources can be clustered4types by SSR marker analysis and main components analysis. The main components of the first type is flue-cured tobacco, the second type is sun-cured tobacco and air-cured tobacco, wild tobacco is the third type, restica tobacco is the fourth type. The genetic similarity coefficients of all tobacco materials are0.81on average, and sun-cured tobacco have more abundant genetic variation degree, its genetic similarity coefficient is0.69.2)According to the statistics of9agronomic characters which including tobacco plant height, stem girth, pitch, field growth period, effective leaves, the max leaf length, the max leaf width, leaf layer height, leaf layer width. The max leaf length and the max leaf width have the biggest coefficient of variation, and the coefficient of variation of them is33.30and30.54, respectively; The max leaf width, plant height and leave layer width have higher genetic diversity index, and the date all of them more than1.74. There are biggish differences between different types of tobacco materials in the agronomic traits, and sun-cured tobacco have the biggest coefficient of variation and diversity index, the values are32.36and2.24,respectively.3)9agronomic traits can be transferred into3main components by principal components analysis, materials of the first principal component had higher plant height, longer pitch, higher leaf layer height and wider leaf layer width, the second has longer leaf length and wider leaf width,the third has higher effective leaves and longer field growth period, the first principal component of tobacco effective more. According to the agronomic characteristics clustering,102tobacco germplasms can be obviously divided into3types, the first type is flue-cured tobacco, the main germplasms of second type is sun-cured tobacco and air-cured tobacco, the third type is rustica tobacco, the result is in good agreement with the SSR’s.2.Analysis of application potential of tobacco germplasm resourcesThis study analyze the application potential of tobacco germplasms according to growth period, disease resistance, the main economic traits and chemical quality index use102tobacco germplasms what plant in Pengshui Country of Chongqing, and compared with Yunyan97as check variety, in order to breed new flue-cured tobacco varietise with better quality tobacco in Chongqing. The results are as following:1)The average field growth period of Yunyan97in Pengshui Country of-Chongqing is-124.53days,9tobacco germplasms’field growth period are shorter5-9days than check variety and have better potential application which includ M373, Guinong1, Coker298, Loushanl, Coker206, G23,29EC3, Shanxi Hanzhong5,Sichuan Qinglong native tobacco and Fuling native tobacco.2) The investigation result of disease resistance show that sun-cured tobacco has higher disease resistance than other type’s. Fuwu native tobacco, Zhongyan103, Fuling Jiaoshi native tobacco have strong disease resistance of tobacco mosaic virus, weather fleck and brown spot.3)15tobacco materials have better economical characters than check variety. Among them, NC82, Coker176, NC27NF, NC95have better economic benefits as more than52113.15CNY/hm2production value and more than90%secondary leaves rate.4)It is observed that there are great differences in chemical quality indexes in different tobacco materials. Jinxing1006, Fuling Jiaoshi native tobacco, NC13, NC95, NC82, HongDayoubianl, M373, Sichuan Langzhong native tobacco, SC71have better coordination for more than90points evaluation value of chemical components coordination.5) The summary of this study indicates that flue-cured tobacco materials includ NC82, NC89, NC95, K346, NC95, M373, Coker298, Coker206, Coker176, Loushanl, Yunyan317, Hongdayoubianl,Yunyan203, and they have the potential as core parent lines.Sun-cured tobacco materials includ Sichuan Langzhong native tobacco, Fuwu native tobacco, Fuling Jiaoshi native tobacco, Sichuan Qinglong native tobacco, Shanxi Hanzhong native tobacco have better phenotypic character than others, so they can be further research as alternative materials of core parent lines. Other germplasms with an advantage can be alternative parental materials for different breeding aim.3. Screening of core SSR primers for tobaccoIn recent years, SSR marker has been widely used in tobacco research, but with too much amount and the lower selecting efficiency bring inconvenience for research, it is necessary to select a number of less tobacco core SSR primers.278pairs of SSR primers which evenly distributed in24chromosomes tobacco are screened on30tobacco germplasm stocks with different relative in this study, then validated the core SSR primers’truth effectiveness to selected a set of core SSR primers used to analysis genetic diversity and construct DNA fingerprint database of tobacco, the results are as follows:1)14primers are selected278pairs of SSR primers which evenly distributed in24chromosomes tobacco, these primers could reflect the difference between species easily with abundant genetic polymorphism and stable codominant.2)140materials are classified by using clustering analysis, the clustering results is roughly same with48pairs SSR primers clustering, can will clearly divided140different types of tobacco materials into four categories, but some of the varieties was different from48pairs SSR primers clustering results.3)12known pedigree tobacco materials are divided into four groups by14pairs of SSR core primers clustering. The results is generally corresponded to known pedigrees that tell us that these core primers are applied to pedigree analysis of tobacco germplasm.4)Combined with agronomic traits and14pairs of core SSR primers marker cluster,39tobacco materials both divid into five groups, and the results by different methods are almost identical, only part varieties are differences each other.14pairs of core SSR primers in this study are effective and can be used for germplasm identification, genetic diversity and pedigree analyze, DNA fingerprint database construction and so on.