Application of Molecular Marker Assisted Selection in Gene Pyramiding and Selection of New Cultivars

The feasibility of molecule markers＇ application in gene pyramiding has been proved,and obvious progresses in crop breeding have been made till now.Furthermore,different QTLs or molecular markers linked tightly to yield,quality or resistance may be used for marker assisted selection.MAS will be applied widely in crop breeding due to the development of more gene-based markers and efficient quantitative trait locus（QTL） as well as lower cost marking systems.

Pyramiding Breeding by Marker-Assisted Recurrent Selection in Upland Cotton: Selected Effects on Resistance to Helicoverpa armigera

The coincidence rates were more than 96% among the instar-weighted average of bioassaysin the lab, the percentage of resistance to Km in the field and the percentage of plantscontaining Bt gene. So, the performance of resistance to Km in the field can be used torepresent the transgenic Bt gene for selecting the resistance to bollworm. The instar-weighted averages were 30.585, 24.182, 16.615, 10.601, 10.123, 7.440 and 7.215 for theC0, P1, M1, M2, MP1, P2 and MP2 populations, respectively. The variance analysisindicated that the instar-weighted average in C0 was greatly significantly higher thanthat in all other populations, i.e., the performance of resistance to bollworm in C0 washighly significantly lower than all other populations. And the resistance in P1 wasgreatly lower than that of M1, M2, MP1, P2 and MP2, and M1 greatly lower than that of M2,MP1, P2 and MP2. There were no significant differences among M2, MP1, P2 and MP2. Withinthe populations of the first cycle selection, MP1 and M1 were greatly significantlyhigher than P1, and MP1 significantly higher than M1. The populations of the second cycleselection were significantly higher than their initial population M1, but no significantdifference among them. The boll size, seed index, the percent of the first harvest yield,fiber length, strength and elongation of the resistant plants to bollworm were significantlylower than that of sensitive plants to bollworm. And the yield of seed and lint cottonof the resistant plant to bollworm were lower than that of the sensitive to bollworm, butno significant difference between them. The boll numbers per plant, lint percent andmicronaire of the resistant plants to bollworm were significantly higher than that of thesensitive plant to bollworm.

Research Progresses of Sugarcane Brown Rust Resistance Gene and Molecular Markers

Brown rust is a main sugarcane disease in China, affecting stable development of sugarcane industry. Resistance breeding is an effective measure to control sugarcane rust, and looking for diverse sugarcane rust resistance alternative resources is another important way to improve rust resistance level. This article reviewed from the aspects of construction of sugarcane genetic map, research progress of rust resistance gene, development of rust resistance molecular markers, and research strategies of rust resistance gene, in order to provide scientific guidance and reference for rust resistance breeding.

Breeding Rice Restorer Lines with High Resistance to Bacterial Blight by Using Molecular Marker-Assisted Selection

Two bacterial blight （BB） resistance genes, Xa21 and Xa4, from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB, by using hybridization and molecular marker-assisted selection technology. Four homologous restorer lines were obtained through testing the R target genes with molecular markers and analyzing parental genetic background. Inoculation of the four lines and their hybrids with the specific strains of Xanthomonas oryzae pv. oryzae, P1, P6 and seven representative strains of Chinese pathotype, C Ⅰ -CⅦ, showed that all of the four lines and their hybrids were highly resistant and presented broad resistance-spectrum to BB. The hybrids of G46A / R207-2 displayed good agronomic characters and high yield potential, and R207-2 was named Shuhui 207.

Breeding of Rice Restorer Line Haihui 818 of Multi-resistant Gene Pyramiding

Haihui 818 is a new restorer line by cross breeding with Hua 23 S and Huahui 8131.Good plant type,high tillering ability,fine grain quality,strong restoring ability and high yield were shown in hybrid production.After artificial inoculation and field stress and molecular market-assisted selection,the results showed that rice-blast resistance genes Pi1,BB resistance genes Xa7,and brown planthopper resistance genes Bph3,Bph14 and Bph15 were pyramided together.Among its hybrids,Bo II You 818(Bo II A/Haihui 818)was approved for commercial production by Hainan Provincial Crop Variety Approval Committee in 2015.

Genetic and genomic analyses for economically important traits and their applications in molecular breeding of cultured fish

The traits of cultured fish must continually be genetically improved to supply high-quality animal protein for human consumption.Economically important fish traits are controlled by multiple gene quantitative trait loci(QTL),most of which have minor effects,but a few genes may have major effects useful for molecular breeding.In this review,we chose relevant studies on some of the most intensively cultured fish and concisely summarize progress on identifying and verifying QTLs for such traits as growth,disease and stress resistance and sex in recent decades.The potential applications of these major-effect genes and their associated markers in marker-assisted selection and molecular breeding,as well as future research directions are also discussed.These genetic and genomic analyses will be valuable for elucidating the mechanisms modulating economically important traits and to establish more effective molecular breeding techniques in fish.

Marker-assisted pyramiding of soybean resistance genes R_(SC4),R_(SC8),and R_(SC14Q) to soybean mosaic virus

Soybean mosaic virus （SMV） is one of the major viral pathogens affecting soybean crops worldwide. Three SMV resistance genes, Rsc4, Rsc8, and Rsc14Q, have been identified and mapped on soybean chromosomes 14, 2, and 13 from Dabaima, Kefeng 1, and Qihuang 1 cultivars, respectively. Soybean cultivar Nannong 1138-2 is widely grown in the Yangtze River Valley of China. In this study, crosses were made between Qihuang l^Kefeng 1 and DabaimaxNannong 1138-2. Ten simple sequence repeat （SSR） markers linked to three resistance loci （Rsc4, Rsc8, and Rsc^4Q） were used to assist pyramided breeding. Pyramided families containing three resistance loci （Rsc4, Rsc8, and Rsc14Q） were evaluated by inoculating them with 21 SMV strains from China. Results indicated that the 10 markers can be used effectively to assist the selection of resistant individuals containing Rsc4, Rsc8, and Rsc14Q. A total of 53 F6 plants were confirmed to contain three homozygous alleles conferring resistance to SMV. Five F7 homozygous pyramided families exhibited resistance to 21 strains of SMV and showed desirable agronomic traits using dual selection. The strategy of pyramiding resistance gene derived from different varieties has practical breeding value in providing broad-spectrum resistance against the existing strains of SMV in China.

Marker-Assisted Pyramiding of Genes Conferring ResistanceAgainst Bacterial Blight and Blast Diseases into Indian RiceVariety MTU1010

Two major bacterial blight （BB） resistance genes （Xa21 and xa13） and a major gene for blastresistance （Pi54） were introgressed into an Indian rice variety MTU1010 through marker-assistedbackcross breeding. Improved Samba Mahsuri （possessing Xa21 and xa13） and NLR145 （possessingPi54） were used as donor parents. Marker-assisted backcrossing was continued till BC2 generationwherein PCR based functional markers specific for the resistance genes were used for foregroundselection and a set of parental polymorphic microsatellite markers were used for background selectionat each stage of backcrossing. Selected BC2F1 plants from both crosses, having the highest recoveriesof MTU1010 genome （90% and 92%, respectively）, were intercrossed to obtain intercross F1 （ICF1） plants,which were then selfed to generate 880 ICF2 plants possessing different combinations of the BB andblast resistance genes. Among the ICF2 plants, seven triple homozygous plants （xa13xa13Xa21Xa21Pi54Pi54）with recurrent parent genome recovery ranging from 82% to 92% were identified. All the seven ICF2plants showed high resistance against the bacterial blight disease with a lesion lengths of only 0.53–2.28 cm, 1%–5% disease leaf areas and disease scoring values of ‘1’ or ‘3’. The seven ICF2 plants wereselfed to generate ICF3, which were then screened for blast resistance, and all were observed to behighly resistant to the diseases. Several ICF3 lines possessing high level of resistance against BB andblast, coupled with yield, grain quality and plant type on par with MTU1010 were identified and advanced forfurther selection and evaluation.

SCAR Markers Assisted Selection for a Bentazon Susceptible Lethality Gene (ben) in Rice

In progenies resulting from crosses involving rice cultivar Norin 8m susceptible to bentazon as the donor of ben gene, SCARs tightly linked to ben were utilized for selection of ben. The homozygous and heterozygous genotypes with ben could be identified with the SCARs. The molecular markers offer a powerful tool for indirect selection of ben and can accelerate the introgression of ben into current rice cultivars.

Breeding of CMS maintainer lines through anther culture assisted by high-resolution melting-based markers

The integrated use of molecular marker-assisted selection (MAS) and anther culture has potential to significantly increase efficiency in plant breeding;however, reports on this kind of practical use are very limited. In the present study, we report the development of cytoplasmic male sterile (CMS) maintainers with aroma, disease resistance and red-brown hulls, as an example of integration of MAS and anther culture in rice breeding. A high-resolution melting (HRM)-based functional molecular marker was developed for the red-brown hull trait caused by a unique mutation (rbh1) in OsCAD2. Functional molecular markers for genes of rice blast resistance (Pi2), aroma (fgr) and red-brown hull (rbh1) were used for precise genotyping of individual plants in the BC1 and BC2F2 populations derived from a cross between CMS maintainers Huaxiang B (pi2–/rbh1–/fgr–) and Rong 3B (Pi2+/RBH1+/Fgr+). A total of 89 doubled haploid (DH) lines were generated from selected BC2F2 plants (Pi2+/rbh1–/fgr–) by anther culture. Seven DH lines were subsequently selected as the potential new CMS maintainers based on their overall performance and high resistance to blast. Our study demonstrated that integration of MAS and anther culture significantly accelerated the development of CMS maintainers with multiple stacked genes.

Breeding of R8012,a Rice Restorer Line Resistant to Blast and Bacterial Blight Through Marker-Assisted Selection

Genetic improvement is one of the most effective strategies to prevent rice from blast and bacterial blight （BB） diseases, the two most prevalent diseases jeopardizing rice production. Rice hybrids with dural resistance to blast and BB are needed for sustainable production of food. An incomplete diallele design resulted in 25 crosses between five blast and five BB resistant germplasm accessions. Only one pair of parents, DH146 ×TM487, showed polymorphism for all the markers to identify one blast resistance gene Pi25 and three BB resistance genes, Xa21, xa13 and xa5, thus it was used in the marker-assisted selection （MAS）. F2 individuals of DH146× TM487 were genotyped using flanking markers of RM3330 and sequence tagged site （STS） marker SA7 for Pi25. The resistant F2 plants with Pi25 were used for pyramiding BB resistance genes Xa21, xa13 and xa5 identified by the markers pTA248, RM264 and RM153, respectively in subsequent generations. Finally, after selection for agronomic traits and restoration ability among 12 pyramided lines, we acquired an elite restorer line, R8012 including all four target genes （Pi25＋Xa21＋xa13＋xa5）. Hybrid Zhong 9NR8012 derived from the selected line showed stronger resistance to blast and BB, and higher grain yield than the commercial checks uniformally in experimental plots, 2007 state-wide yield trial and 2008 nation-wide yield trial. This study provides a paradigmatic example to show that MAS is a practically feasible tool in effectively pyramiding multiple resistance genes. The resultant restoring line and its hybrid would play an important role in securing rice production in China.

西北条锈菌源区冬小麦育种抗条锈病基因的利用现状与策略

【目的】了解中国小麦条锈病西北重要越夏菌源区甘肃陇东和陇南近20年育成小麦品种(系)中抗条锈病基因的利用情况,为陇南小麦条锈病遗传多样性控制,持久抗病品种的培育和可持续绿色健康生态农业奠定基础。【方法】于2019—2020年和2020—2021年种植季对117份冬小麦品种(系)甘肃清水县和四川郫都区进行成株期抗条锈病鉴定,2021年分别用条锈菌CYR33和CYR34对117份品种(系)进行苗期抗条锈病鉴定,并利用分子标记对15个抗条锈病基因进行检测。【结果】田间成株期对条锈菌主要流行致病性混合小种抗病的品种(系)占29.1%,其中,25.6%为陇南区域品种(系),3.4%为陇东区域品种(系),另有25.6%陇南区域感病品种(系)表现慢病性(严重度<20%)。有70.1%品种(系)苗期对CYR33表现抗病,其中,57.3%为陇南区域品种(系),12.8%为陇东区域品种(系);仅6.0%品种(系)苗期对CYR34具有抗病性,为陇南区域的兰天131等7个品种(系)。苗期和成株期抗病品种(系)以2010年后育成的兰天、中梁、天选、兰航选系列品种为主。分子标记检测结合系谱分析,发现抗条锈病基因Yr9、Yr10、Yr17、Yr18、Yr26、Yr28、Yr29、Yr30、Yr41、Yr46、YrZH22和YrZH84在所有检测品种(系)中的频率分别为49.6%、1.7%、12.8%、7.7%、12.8%、20.5%、10.3%、34.2%、2.6%、16.2%、15.4%和27.4%,且多以基因聚合体形式存在于品种(系)中,62.4%品种(系)中聚合了2—5个抗条锈病基因,YrZH84、YrZH22和Yr17中的一个或多个基因与其他抗条锈病基因聚合后,品种(系)的条锈病抗性明显高于其他基因组合。此外,在陇南菌源区,以种植小麦为主的山旱地区域(条锈菌越夏区)所推广的品种(系)中,含有Yr10、Yr17、Yr18、Yr28、Yr29、Yr30、Yr41和Yr46的频率较高,越冬区(川水地)推广品种(系)中主要有Yr26、Yr30、YrZH22和YrZH84,越夏区和越冬区品种(系)的抗性遗传背景差异明显,且越夏区品种(系)含有的抗病基因类型多样性高于越冬区。【结论】在越夏菌源区甘肃陇南、陇东的品种(系)中,抗条锈病基因分布频率、抗病基因类型及数量均有明显提高,避免了品种抗病遗传背景单一化问题,实现了品种(系)中的抗病基因较为复杂多样,部分品种的抗病性保持时间长,表明陇南地区利用小麦品种遗传多样性控制条锈病策略的实施已初显成效。

小麦条锈病抗性基因定位及分子标记技术研究进展

条锈病流行对小麦生产造成巨大损失,选育和种植持久抗性品种是防治小麦条锈病最经济有效的策略。为达到多基因聚合培育持久抗病品种的目标,必须不断发掘抗病种质、解析其抗病遗传机制并开发分子标记。基于文献,对条锈病抗性基因发掘涉及的抗病性、分子标记、基因定位方法和定位进展及其在育种中的应用进行了综述,明确了小麦条锈病基因定位涉及技术的现状、局限性及优势,从而为后续的条锈病抗性基因发掘、多基因聚合和持久抗性小麦品种的选育与生产布局提供技术指导,以降低西北麦区和小麦主产区条锈病流行的频率,进一步促进国家粮食安全。

抗稻瘟病水稻恢复系的分子标记辅助选育及抗性鉴定

【目的】开展抗稻瘟病水稻恢复系的分子标记辅助选育及抗性鉴定,为育成持久、广谱抗病优质杂交水稻新品种提供优异的遗传资源和技术参考。【方法】利用分子标记辅助选择和回交育种技术,将持久、广谱的抗稻瘟病基因Pi1、Pi2和Pigm导入恢复系桂R1703,获得了单基因、双基因和三基因导入系,并对其进行稻瘟病鉴定和农艺性状调查,分析不同抗稻瘟病基因间的抗性效应及抗性基因导入对受体亲本农艺性状的影响。【结果】通过对杂交后代和回交群体的Pi1、Pi2和Pigm基因相关分子标记检测,发现抗稻瘟病基因Pi1、Pi2和Pigm已成功导入到桂R1703中,筛选获得7个携带有抗稻瘟病基因且抗性和农艺性状综合表现优良的导入株系,表现出较强的稻瘟病抗性。单基因导入系中,抗稻瘟病基因的抗性效应排序为为Pigm>Pi2>Pi1;双基因和三基因导入系的稻瘟病抗性均强于单基因导入系,尤其以三基因导入系抗性最强,不同基因聚合的抗性效应排序为Pi1+Pi2+Pigm>Pi2+Pigm>Pi1+Pigm>Pi1+Pi2。7个瘟病抗性基因导入株系与桂R1703在穗长和千粒重方面无显著差异(P>0.05,下同),有2个瘟病抗性基因导入系的株高显著高于桂R1703(P<0.05,下同);有1个瘟病抗性基因导入系的单株有效穗显著高于桂R1703;有3个瘟病抗性基因导入系的单穗总粒数显著高于桂R1703;有5个瘟病抗性基因导入系结实率显著低于桂R1703;有2个瘟病抗性基因导入系的单株产量显著低于桂R1703;有4个瘟病抗性基因导入系的单株产量显著高于桂R1703。【结论】通过分子标记辅助选育可有效聚合多基因(Pi1、Pi2和Pigm基因),使恢复系桂R1703的稻瘟病抗性得到明显提升,获得一系列抗稻瘟病且与亲本其他性状相近的遗传材料,可作为亲本材料用于选育抗病优质的杂交稻。

马铃薯孢囊线虫抗性育种研究进展

马铃薯孢囊线虫(Potato cyst nematode,PCN)主要指马铃薯金线虫(Globodera rostochiensis)和马铃薯白线虫(G.pallida),是马铃薯中最重要的植物寄生线虫,具有早期症状不明显、易传播、潜伏期长、根治困难等特点。因其严重危害性和经济影响性,该类线虫被多个国家列为检疫性有害生物。利用马铃薯孢囊线虫抗性基因选育并种植抗性品种,是降低马铃薯孢囊线虫危害的经济、有效、可持续发展策略。综述简述马铃薯孢囊线虫的分类关系与致病型分型法,以及对马铃薯孢囊线虫耐受性和抗性定义及其评价方法;详细介绍目前常用马铃薯孢囊线虫抗性基因及分子标记,以及马铃薯孢囊线虫抗性育种研究进展并进行展望。

烟草基因组辅助育种研究进展

优质的烟草品种是促进烟草经济发展的基础。2010年以来,烟草基因组学迅速发展,推动了烟草遗传进化、功能遗传学等多个研究领域的进步,为烟草育种提供了新的工具和途径。本文总结了烟草基因组测序组装和功能研究的最新成果,从烟草遗传连锁图谱构建、数量性状基因座(QTL)定位、全基因组关联分析(GWAS)以及QTL定位和GWAS联合分析4个方面阐述了烟草分子标记辅助选择育种(MAS)的发展现状,并综述了全基因组选择(GS)和基因编辑(GE)的技术理论以及它们在烟草育种中的应用进展。针对目前烟草基因组辅助育种(GAB)存在的问题和不足,指出要充分利用烟草基因组信息,加快分子标记的开发,推进基因芯片的应用和加强高通量表型监测平台的建设,进而推进GAB在烟草育种上的应用。

分子标记辅助选择W_(x)^(mp)基因改良晚粳品种宁84稻米品质

为改良晚粳水稻品种宁84的稻米品质,培育低直链淀粉含量的软米粳稻新品系,利用携带软米基因W_(x)^(mp)的水稻品种南粳9108为供体亲本,以晚粳品种宁84为受体亲本,利用分子标记辅助选择将W_(x)^(mp)基因回交导入到宁84中,创制了宁84(W_(x)^(mp))改良系。结果显示:宁84(W_(x)^(mp))改良系的农艺性状与宁84差异不显著,其背景回复率达到98.7%;与宁84相比,其直链淀粉含量由17%降低到10%左右,胶稠度由70 mm增加到最高80 mm;改良系的垩白度和垩白粒率显著增高,透明度显著降低,碱消值保持不变,整精米率和精米率显著高于对照,食味品质明显提升。宁84(W_(x)^(mp))改良系的成功培育,为今后粳稻软米新品系的选育及推广打下了良好基础。

藏绵羊多胎性状育种:遗传基础、分子标记应用及未来发展策略

文章全面探讨了藏绵羊多胎性状的遗传基础、分子标记在绵羊育种中的应用,以及未来育种策略的发展方向。概述了FecB基因对多胎品系绵羊培育的影响,以及绵羊繁殖相关编码RNA和非编码RNA的研究进展。分析了分子标记辅助选择在提高多胎繁殖力中的应用,特别是哈萨克羊FecB基因多态性的案例研究,以及遗传修饰技术在绵羊分子设计育种中的潜力和挑战。讨论了综合传统育种与分子育种方法的重要性,多胎性状在绵羊遗传资源保护中的作用,以及新的分子标记的发现和遗传修饰技术的进步。提出了对未来研究和应用的建议,强调了环境因素与遗传因素交互作用的重要性,并呼吁在育种进程中考虑遗传资源的保护与可持续利用。

Current Status of Conventional and Molecular Interventions for Blast Resistance in Rice

Pyricularia oryzae anamorph of Magnaporthe oryzae is one of the most notorious fungal pathogens causing severe economic loss in rice production worldwide. Various methods, viz. cultural, biological and molecular approaches, are utilized to counteract this pathogen. Moreover, some tolerant or resistant rice varieties have been developed with the help of breeding programmes. Isolation and molecular characterization of different blast resistance genes now open the gate for new possibilities to elucidate the actual allelic variants of these genes via various molecular breeding and transgenic approaches. However, the behavioral pattern of this fungus breakups the resistance barriers in the resistant or tolerant rice varieties. This host-pathogen barrier will be possibly countered in future research by comparative genomics data from available genome sequence data of rice and M. oryzae for durable resistance. Present review emphasized fascinating recent updates, new molecular breeding approaches, transgenic and genomics approaches(i.e. mi RNA and genome editing) for the management of blast disease in rice. The updated information will be helpful for the durable, resistance breeding programme in rice against blast pathogen.

分子标记辅助选择小麦赤霉病抗病基因聚合体

赤霉病和条锈病是小麦的两种主要病害,两种病害都会影响小麦的品质和产量。贵协2号高抗条锈病、感赤霉病,NMAS22高抗赤霉病并携带4个抗赤霉病基因。为选育抗赤霉病、抗条锈病的品种,本研究将贵协2号与NMAS22组配,在其分离世代(F 2)采用自然诱发法、单花滴注法分别对条锈病和赤霉病进行抗性鉴定,同时利用与抗赤霉病基因Fhb1、Fhb2、Fhb4、Fhb5紧密连锁的6个分子标记对群体中条锈病抗病株进行检测,筛选具有单个或多个抗赤霉病基因组合的抗病株。抗性鉴定显示,共有349个单株抗条锈病,467个单株抗赤霉病;分子检测显示,携带Fhb1、Fhb2、Fhb4、Fhb5基因的单株分别有201,245,248,194株,同时携带有2,3,4个基因的单株分别有79,140,85株。相关分析显示,携带Fhb1基因与赤霉病抗性呈极显著相关。