Study On Genetic Evolution Of Kam Sweet Rice And Influence From Dong's Traditional Culture

"Kam Sweet Rice" is an special kind of original ecological rice landrace and had been cultivated for thousands of years in southeast of Guizhou province.Kam Sweet Rice has many outstanding qualities,including the strong resistance to diseases,pests,barren and adverse situation,difficulty of threshing,and well glutinous features.Plentiful Kam Sweet Rice resources are the indispensable material basis and cultural symbol in the production and daily life and culture customs of Dong people,which are still cultivated in large area.Kam Sweet Rice resources has a long history and many primitive features,other traditional rice varieties,wild rice from Guizhou and other provinces may be influenced by it in the process of cultivation and evolution.In addition,Kam Sweet Rice and other rice landrace resources formed different varieties with different quality characteristics due to the influence of different traditional culture of minorities.However,it is unclear that how the traditional culture influence to the formation of quality characteristics of Kam Sweet Rice.In view of this,we select 315 Kam Sweet Rice resources,578 other rice landraces from Guizhou province,180 rice landraces from other adjacent provinces,42 wild rice germplasms as materials,take the methods of phenotypic character evaluation and SSR,SNP molecular marker technology,study the genetic evolution relationship between Kam Sweet Rice resources and other rice varieties;and through ethno-biology approaches,investigate the influence mechanism of Dong's traditional culture to the formation of Kam Sweet Rice.This study is of great significance to comprehensively evaluate the genetic basis,dig breeding value of Kam Sweet Rice and promote ethnic traditional knowledge.Main results as following:(1)Ethno-biology investigation conducted in 28 ethnic minority villages in Congjiang,Liping and Rongjiang county of southeast of Guizhou province,We collected 156 accessions of Kam Sweet Rice germplasms,and found that some Dong villages still have been cultivating Kam Sweet Rice in large area(more than 80%)so far,and reserved 20-30 varieties,which showed very high levels of genetic diversity.Furthermore,we also found that Dong's diet culture,festival celebration,religious belief and traditional farming practices promote the formation,protection and utilization of Kam Sweet Rice effectively.(2)Comparing the phenotypic traits between Kam Sweet Rice resources and other 16 populations in the field,including plant height,panicle length,spike neck length,productive panicles and grains per panicle,spikelet fertility,knot spacing,sword leaf length and width,leaf color,leaf pubescence,leaf curling,awn color,awn length,awn distribution,glume color,glume tip color.The results of clustering and comparison analysis of phenotypic characteristics show that Kam Sweet Rice have the most close genetic relationship with Guizhou V Eco-rice farming zone,followed by five other Eco-rice farming zones and Guangdong,Guangxi populations,then Zhejiang,Hunan,Jiangxi,Anhui populations,the genetic distance with Hubei,Jiangsu and wild rice populations are the farthest.(3)The genetic diversity,genetic differentiation and genetic relationship between Kam Sweet Rice population and neighboring province population,six Guizhou eco-rice farming zones,wild rice population were detected by means of 36 pairs of SSR microsatellite markers,it is found that the allelic variation number and polymorphism information content(PIC)of all materials is up to 24.61 and 0.7524 on average,have a higher genetic diversity.Kam Sweet Rice population has a unique genetic background.80%of all varieties were clustered together.Considering every genetic diversity index,the results showed that Kam Sweet Rice have a closest genetic relationship with Guangdong,Guangxi and Guizhou V Eco-farming zone,followed by Guizhou I,?,?,? Eco-farming zone and Jiangxi,Zhejiang,Hunan,Hubei population,However,the genetic relationship between Kam Sweet Rice and wild rice,Jiangsu,Yunnan,Guizhou ?Eco-farming zone were distant.AMOVA analysis found that genetic variation of 17 populations were mainly due to the variation within population(81.87%).(4)According to the special biological characteristics of strong resistance to diseases,pests,barren and adverse situation preserved by Kam Sweet Rice,we selected seven non-linked nuclear genes,including SKC1,Bph14,GS5,Pid3,SAP8,Ehd1,Xa23 to detect the haploid type,frequency and distribution in 17 populations,the results showed that the nucleotide diversity between Kam Sweet Rice and neighboring provinces population was similar,and was significantly less than Guizhou other rice landraces.The haplotype of Bph14,Xa23 and Pid3 in Kam Sweet Rice population is not only rich(the haplotype frequency is 60%?80%),but also has a significant difference with Guizhou six Eco-rice faming zones,and has a certain similar genetic relationsip with neighboring provinces(Hunan,Zhejiang,Jiangxi,Anhui,Guangdong,Guangxi,Jiangsu)and wild rice population.In view of the haplotype composition and ratio about Ehdl,GS5,SAP8 and SKC1,we found that Kam Sweet Rice and Guizhou V Eco-farming zone,Jiangxi,Hubei,Hunan,Guangxi,Guangdong population has a close genetic relationship.AMOVA showed that genetic variation of 17 populations in 7 loci were mainly due to the variation within population(86.82%).Analysis of genetic differentiation coefficient in 7 genes showed that Kam Sweet Rice and Guizhou V Eco-rice farming zone,Jiangxi,Guangxi,Hubei,Hunan,Zhejiang,Anhui and Yunnan have a smaller genetic differentiation coefficient(Fst? =0.05),with a close genetic relationship;There was a middle level genetic differentiation with Guizhou I,3,4,6 Eco-rice farming zone,wild rice,Jiangsu and Guangdong population(Fst=0.07?0.12);the most significant genetic differentiation with Guizhou ? Eco-rice farming zone population.(5)In order to study the origin and evolution of Kam Sweet Rice,we selected rice landraces from Guizhou and neighboring provinces as well as wild rice based on Dong's population distribution and migration route,compared the genetic relationship between Kam Sweet Rice and other rice varieties with the combination method of SSR and SNP molecular markers.The results showed that Kam Sweet Rice has a close genetic relatives with Guangdong,Guangxi,Jiangxi,Zhejiang,Hunan and Guizhou I,III,IV,V Eco-rice farming zone.Therefore we preliminary speculate that:Kam Sweet Rice is a kind of special rice landrace and adapt to the geographical environment and climate condition in Qiandongnan cultivated by Dong people through hundreds or thousands of years in the process of Dong's migrations from neighboring province to southeast of Guizhou.(6)The genetic diversity of Kam Sweet Rice of 1980s population(147 accessions)and 2015s population(168 accessions)was compared by using two measures of SSR and SNP molecular markers.We found that various genetic diversity index of 1980s population is higher than(some with a significant or very significantly level)2015s.The specific allele number detected in 1980s population is 2 times than 2015s.In 36 pairs of SSR markers,the specific allele ratio of 26 pairs of SSR markers of 1980s higher than that of 2015s.Therefore,over the past 35 years,the genetic diversity,nucleotide polymorphisms and heterozygosity of Kam Sweet Rice resources has been greatly reduced,a large number of alleles have been lost.In addition,the number and frequency of dominant and rare haplotypes not only reduced,but also tend to be simplified or even disappear.