广西邕宁普通野生稻(Oryza rufipogon Griff.)种群遗传多样性及核心种质构建研究

[目的]研究广西邕宁普通野生稻种群的遗传多样性和核心种质构建,为普通野生稻种群保护提供依据。[方法]从水稻12条染色体上均匀选取24对SSR标记对243份样本进行遗传多样性分析。[结果]结果表明,24对引物均表现出多态性,多态位点比率为100%;24个多态位点共检测出103个等位变异,平均等位基因数A为4.291 7,平均有效等位基因数E是2.511 2,平均期望杂合度He为0.573 2,平均多态信息含量PIC为0.572 0。根据聚类结果分析,从243份材料中筛选出31份核心种质,包含了24个SSR位点检测到的所有的遗传变异,其平均期望杂合度He是0.595 8,平均多态信息含量PIC是0.586 3,基本上可以代表广西邕宁普通野生稻种群的遗传多样性。[结论]广西邕宁普通野生稻资源具有丰富的遗传多样性。

Research Progress on Genetic Diversity and Its Ecological Conservation of Endangered Dongxiang Wild Rice (Oryza rufipogon Griff.)

It is of great importance for the analysis on genetic evolution mechanism, and rice breeding utilization by estimation and protection of genetic diversity of pre- sent DXWR （Oryza rufipogon Griff.）. This study has summarized genetic diversity and protection achievements of DXWR from many aspects like varied conservations, years, generations, other species of wild rice and cultivated rice. In this study, a u- nified and scientific evaluation system of genetic diversity is encouraged to be built and suggestions on research prospect and ecological conservation of DXWR genetic diversity have been proposed.

普通野生稻与栽培稻杂交后代部分材料的RAPD分析

为了将云南元江普通野生稻的部分优良性状转移到常规栽培稻合系35中,以这2种材料为杂交亲本获得了100多个BC2F3株系,并利用RAPD分子标记技术进行了早期选择辅助分析。在株高和结实率2个性状的多样性分析中,5个引物分别扩增出了47和58条带,多态条带比率(PPB)分别为74.47%和86.21%,Nei’s平均多样性指数分别为0.3085和0.2921。在分蘖率遗传多样性的分析中,10个引物共扩增出129条带,其中有124条为多态条带,多态条带比率(PPB)达96.12%。Nei’s平均多样性指数为0.2464。结果表明,RAPD标记技术能有效地指导田间的育种选择。通过该技术发现了1株材料具有较大的变异,应在以后的育种中给予高度重视。

Effect of Low Temperature and Sparse Light Conditions on Cold Tolerance of Different Rice Lines at Seedling Stage

Low temperature and sparse light in early spring is one of the factors causing reduction for rice production. So it is important to develop cold tolerance cultivars. In the present study, cold tolerance characters of 36 parents and 423 rice lines from 68 hybrid groups were investigated at seedling stage under low tempera- ture and sparse light conditions in field. There were 10 parent accessions with strong cold tolerance of level 1. Among them, 3 were common wild rice accessions; 4 were japonica rice cultivars; 2 were indica rice; 1 was offspring from hybrid be- tween indica and japonica.There were 33 lines with strong cold tolerance of level 1 from the hybrid groups of common wild rice,and 15 from the hybrid groups of IRBB5, and only 3 from the hybrid groups of BPHR96. There were abundant cold tolerance resources in rice germplasm. It was feasible to develop cold tolerance cul- tivars from the hybrids among common wild rice, japonica cultivars and indica culti- vars.

普通野生稻花器性状及异交结实性分析

以7个普通野生稻(Oryza rufipogon Griff.)和3个栽培稻(Oryza sativa L.)为材料,研究普通野生稻的花器性状和异交结实率及其相关性。结果表明,普通野生稻的花药长度和宽度、柱头长度和宽度及花粉量均比栽培稻大,但其花粉粒大小、花粉活力、花粉可育度和套袋自交结实率均比栽培稻小。相关分析结果表明,普通野生稻的花药长度与花药宽度、花粉量与花药宽度、柱头长度与柱头宽度、柱头宽度与花柱夹角分别呈显著正相关,花粉可育度与花粉活力呈极显著正相关;普通野生稻与栽培稻的异交结实率与其花器性状和套袋自交结实率之间无显著相关性。

Analysis on Genomic Structure Changes and Diversity of Introgression Lines in Dongxiang Wild Rice(Oryza rufipogon Griff.)

[Objective] The aim of the study was to make research on genomic struc- ture variation and variety analysis of Dongxiang wild rice. [Method] Introgression groups of BC1F6 were based on donor of Oryza rufipogon Griff. and receptor of O. sativa sp. indica Kate. Strains of 239 in the group were analyzed on Polymor- phism with the help of 25 couples of SSR primers distributed in 12 pairs of chromo- somes. [Result] Gene fragments of O. rufipogon Griff. were found penetrated in the 25 microsatellite sites and most of the groups kept the parents of Xieqinzao B or DNA sequence of O. rufipogon Griff. The average rate of recurrent homozygous bands was 78.13% in the ILs, but the highest was 94.98% （amplified by primer RM131） and the lowest was 60.25% （RM171）. The average rate of donor homozy- gous bands was 13.37%, but the highest was 32.64% （RM171） and the lowest was 2.93% （RM1095）. There were numerous heterozygous sites in the population and the average heterozygosis rate was 5.62%, while the highest was 10.04%（RM401）. Moreover, we found some parental fragments were lost and some novel fragments were not detected in either parent in BC1F6 population. The average rate of lost bands was 2.88%, while the highest was 13.39% （RM311） and the lowest was 0 （RM401）. The average rate of new bands was 1%. The average of Nei＇s gene di- versity （He） and Shannon＇s Information index （I） were 0.276 and 0.457 respectively in high generation of introgression lines. [Conclusion] The study demonstrated that distant hybridization led to extensive genetic and epigenetic variations in high gener- ation of introgression lines, which expanded the base of genetic variation and laid an important foundation for rice improvement and germplasm innovation.

Identification of a Resistance Gene bls1 to Bacterial Leaf Streak in Wild Rice Oryza rufipogon Griff

Bacterial leaf streak （BLS） of rice, caused by Xanthomonas oryzae pv. oryzicola （Xoc） is a worldwide destructive disease. Development of resistant varieties is considered to be one of the most effective and eco-friendly ways to control the disease. However, only a few genes/QTLs having resistance to BLS have been identified in rice until now. In the present study, we have identified and primarily mapped a BLS-resistance gene, blsl, from a rice line DP3, derived from the wild rice species Oryza rufipogon Griff. A BC2F2 （9311/DP3//9311） population was constructed to map BLS-resistance gene in the rice line DP3. The segregation of the resistant and susceptible plants in BCzFz in 1：3 ratio （Z2=0.009, Z20 05,1=3.84, P〉0.05）, suggested that a recessive gene confers BLS resistance in DP3. In bulked segregant analysis （BSA）, two SSR markers RM8116 and RM584 were identified to be polymorphic in resistant and susceptible DNA bulks. For further mapping the resistance gene, six polymorphic markers around the target region were applied to analyze the genotypes of the BC2F2 individuals. As a result, the BLS-resistant gene, designated as blsl, was mapped in a 4.0-cM region flanked by RM587 and RM510 on chromosome 6.

Identification of a novel planthopper resistance gene from wild rice(Oryza rufipogon Griff.)

Rice planthoppers,including brown planthopper(BPH)and white-backed planthopper(WBPH),are the most destructive pests in Asian rice cultivation regions.Planthopper resistance genes that have been mapped and characterized advance our understanding of underlying resistance mechanisms and facilitate the breeding of resistant varieties,thereby contributing to an efficient pest management strategy.In this study,a novel resistance gene Bph38 derived from the wild rice species Oryza rufipogon Griff.was found to confer high resistance to BPH and WBPH.Conventional mapping was performed to identify regions associated with BPH and WBPH resistance,and two mapping efforts led to the same region on chromosome 4 flanked by markers RM16563 and RM16763.Bulked-segregant analysis and next-generation sequencing were performed using the same population to detect the resistance gene.Conventional mapping narrowed the region to a 12.3-Mb segment,and fine mapping using BC1 F2 recombinants identified a 79-kb segment flanked by markers YM112 and YM190.Near-isogenic lines(NILs)carrying Bph38 in the 9311(indica)and BR54(japonica)genetic backgrounds were developed by crossing and backcrossing with marker-assisted selection.The agronomic traits and BPH and WBPH resistance of the NILs were similar to those of the recurrent parents.Mandatory feeding and host-choice tests revealed that Bph38 showed both antibiotic and antixenotic effects in both insects,with stronger effects in indica-background lines.Further fine mapping and characterization of the major gene may result in map-based cloning of the gene and allow its application in breeding insectresistant rice varieties.

Genetic diversity of Oryza rufipogon Griff. in Hainan Province analyzed by ISSR and SSR markers

Assessment of genetic diversity is an essential component in germplasm characterization and conservation.There are three wild rice species in Hainan Province,including Oryza rufipogon Griff.In order to detect the genetic diversity of different populations of Oryza rufipogon in Hainan,ISSR(inter-simple sequence repeat)and SSR(simple sequence repeat)markers were used to investigate 180 accessions from six localities in Hainan.Fourteen ISSR primers amplified 185 alleles with 171(92.43%)polymorphic,the number of alleles ranged from 8 to 17,with an average of 13.14 alleles per locus.Thirty-eight pairs of SSR primers used in this study amplified 213 alleles with 190(89.20%)polymorphic,the number of alleles ranged from 2 to 14,with an average of 5.66 alleles per locus.Both ISSR and SSR analyses revealed a high level of genetic diversity in the wild populations.The population with the highest genetic diversity is Wanning(WN),and the population with lowest genetic diversity is Wenchang(WC).The results of a UPGMA cluster using the NTSYS program showed that each population has a low degree of genetic differentiation.Furthermore,the Mantel test revealed that the genetic similarities detected by ISSR and SSR were significantly correlated(r=0.8634,t=93.67)when detecting genetic diversity at the species level.The two molecular marker systems were able to determine the genetic diversity among Oryza rufipogon,and the two groups of indexes obtained by using the two markers have a high level of consistency.

＂Had He a Hand to Write This？＂ Missing ＂Secretary＂ Hands

When Elizabethan＇s were trained to read and write, the handwriting they first learned was ＂Secretary＂ （or ＂Secretarial＂） hand, reflecting the style used by monks and scribes well back into the Middle Ages. Only in the mid-1500s did an alternative hand called ＂Italic＂ （or ＂Italianate＂） slowly begin to be adopted as a second hand, reflecting handwriting used on the continent, and Italic was rarer than Secretary until well after 1600. Today, extant Elizabethan handwriting samples normally show each person used both hand styles, and where only one hand is extant for a given person, it is usually a Secretary hand. Thus, it＇s a surprise that two noblemen, the great William Cecil, Lord Burghley, and his son-in-law Edward DeVere, the 17th Earl of Oxford, are each assumed to have only Italic hand samples among their voluminous collections of handwriting. Did they not learn and never use Secretary hands, or is it that any Secretary hands in their documents are simply presumed to be written by clerks？ This article begins with questioning whether the two men really were limited to Italic hands, fmds a few plausible Secretary hand samples for one of them （possibly for both）, reconstructs a hypothetical Italic alphabet for him, and nominates many candidate manuscripts （MSS, singular MS） for having been written or contributed to by him, some of which may be relevant to Shakespeare studies. Other subjects touched on are calligraphy, a clerk （or amanuensis）, and griffe de notaire （literally a ＂notary＇s scratch＂, or identifying scribble）.

从普通野生稻中鉴定栽培稻F_1花粉不育座位Sb的中性基因

花粉不育是栽培稻(Oryza sativa L.)籼粳亚种间杂种F1普遍存在的现象,是杂种优势利用的主要障碍之一.至少有6个基因座位控制籼粳亚种间F1的花粉不育,各座位存在的花粉育性中性基因可望克服各自的不育性,所以挖掘和利用不同座位的花粉育性中性基因具有重要意义.本文在栽培稻F1花粉不育基因Sb座位已精细定位和广东高州普通野生稻(O.rufipogen Griff.)(以下简称高州野生稻)具有丰富遗传多样性的基础上,分别以粳稻台中65(编号为E1,基因型SbjSbj)及其Sb座位的近等基因系E2(基因型SbiSbi)为母本,12份不同编号的高州野生稻分别为父本,组配成对测交组合并检测各组合F1的花粉育性,初步鉴定可能具有花粉育性中性基因的材料,并发展相应的F2群体,利用4对与Sb座位紧密连锁的分子标记,分析上述成对测交组合F2群体分子标记的分离情况,并与花粉育性的分离进行统计检验.结果表明,编号为GZW099的高州野生稻与E1及E2组配的成对测交组合的F1花粉育性分别为(89.22±1.07)%和(85.65±1.05)%,表现正常可育且经t检验差异不显著;4对分子标记在相应的F2群体中的3种基因型分离比例符合孟德尔分离比例(1:2:1),且3种基因型对应的平均花粉育性差异不显著,说明该编号的野生稻在Sb座位携带的等位基因与台中65及E2的等位基因均不存在显著互作,因此鉴定GZW099在Sb座位携带花粉育性中性基因,命名为SbnSbn,为进一步研究和克服籼粳杂种不育性提供了理论基础和遗传资源.

普通野生稻中S5n基因的鉴定及其胚囊育性研究

普通野生稻具有丰富的遗传多样性,蕴藏许多有利基因.利用S5n功能性标记对来自中国14个不同居群的441份普通野生稻进行检测,发现其中18份可能携带有S5n基因,全部为杂合型,分别来自5个居群,包括广东遂溪13份,广西玉林2份,海南临高、广东高州和江西东乡各1份.进一步对这些材料S5座位可能存在的缺失及其两端DNA进行测序,发现全部材料缺失的DNA片段都与已知携带有S5n的品种02428一致,说明这18份材料确实存在S5n基因.对其中的15份材料自交一代进行基因型检测,检测到3种不同的基因型植株,其分离比(S5iS5i/S5jS5j:S5nS5i/j:S5nS5n)严重偏离1:2:1,其中S5n的杂合型和纯合型植株比例明显偏少,说明部分S5n配子可能无法正常受精.对4份代表性材料的S5座位进行全序列测定并与栽培稻比较,显示普通野生稻S5n序列出现少数碱基的差异.初步推测S5n基因在普通野生稻中已形成,属于古老的基因.对携带有S5n材料的胚囊育性进行研究,发现育性总体偏低,表明这些材料还可能存在除S5座位外决定胚囊育性其他座位的互作.

Identification of quantitative trait loci associated with salt tolerance at seedling stage from Oryza rufipogon

Soil salinity is one of the major abiotic stresses affecting plant growth and crop production.In the present study,salt tolerance at rice seedling stage was evaluated using 87 introgression lines（ILs）,which were derived from a cross between an elite indica cultivar Teqing and an accession of common wild rice（Oryza rufipogon Griff.）.Substantial variation was observed for four traits including salt tolerance score（STS）, relative root dry weight（RRW）,relative shoot dry weight（RSW） and relative total dry weight（RTW）.STS was significantly positively correlated with all other three traits.A total of 15 putative quantitative trait loci（QTLs） associated with these four traits were detected using single-point analysis,which were located on chromosomes 1,2,3,6,7,9 and 10 with 8%-26%explaining the phenotypic variance.The O. rufipogon-derived alleles at 13 QTLs（86.7%） could improve the salt tolerance in the Teqing background.Four QTL clusters affecting RRW, RSW and RTW were found on chromosomes 6,7,9 and 10,respectively.Among these four QTL clusters,a major cluster including three QTLs （qRRWIO,qRSWIO and qRTWIO） was found near the maker RM271 on the long arm of chromosome 10,and the O.rufipogon-derived alleles at these three loci increased RRW,RSW and RTW with additive effects of 22.7%,17.3%and 18.5%,respectively,while the phenotypic variance explained by these three individual QTLs for the three traits varied from 19%to 26%.In addition,several salt tolerant ILs were selected and could be used for identifying and utilizing favorable salt tolerant genes from common wild rice and used in the salt tolerant rice breeding program.