兼抗白粉、条锈病小偃麦渗入系CH7124抗性遗传及细胞学鉴定

CH7124是通过八倍体小偃麦TAI8335与感病小麦杂交、回交育成的兼抗白粉病、条锈病的小偃麦种质系。利用抗性接种鉴定、细胞学和基因组原位杂交(GISH)技术相结合的方法,对CH7124的抗性来源、遗传方式及细胞学特征进行了分析和鉴定。结果表明,CH7124在苗期和成株期对条锈菌系CYR29、CYR31、CYR32、CYR33和白粉菌系E09、E20、E21、E26表现为免疫或近免疫,其抗性来自中间偃麦草,受1对显性核基因控制;CH7124的根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期I(PMC MI)绝大多数细胞内可观察到21个二价体,平均配对构型为2n=0.30 I+20.79 II+0.04 III;与普通小麦中国春、绵阳11的杂种F1中,有80%以上的花粉母细胞可观察到2n=21Ⅱ的染色体构型,其平均配对构型均为2n=21II。说明CH7124具有与普通小麦相似的染色体结构和规则的配对构型。由于利用以中间偃麦草总DNA为标记探针的原位杂交未观察到可见的外源DNA杂交信号,进一步证明CH7124是一个小麦-中间偃麦草的隐形异源渗入系。     

小麦-中间偃麦草6J~S/6B代换系的分子细胞学鉴定

将近缘植物的抗病基因导入小麦是改良小麦抗病性的重要途径之一,对其外源染色体进行准确鉴定能够提高外源基因的选择与利用效率。本研究分别利用小麦白粉病、条锈病菌生理小种接种、荧光原位杂交和分子标记的方法对来源于中间偃麦草的部分双二倍体TAI7047为中间亲本创制的新种质CH357进行了鉴定分析。结果显示,CH357是一个小麦-中间偃麦草6JS/6B代换系,兼抗小麦白粉病、条锈病2种病害,其抗性可能来源于中间偃麦草的6JS染色体,可以作为一个小麦白粉病和条锈病新抗源进行小麦抗性遗传改良。基于中间偃麦草第6同源群Contig序列开发了160个STS标记,其中8个可作为识别小麦-中间偃麦草异代换系CH357中6JS染色体/片段的特异标记,为中间偃麦草6JS染色体/片段的鉴定提供较为经济和方便的检测手段。     

抗白粉病基因PmCH1302的遗传分析及染色体定位

CH1302是以来源于中间偃麦草的八倍体小偃麦TAI7047为桥梁亲本选育的高抗白粉病的小麦新品系,对白粉菌多个流行小种均表现出良好抗性。为了解其抗白粉病基因来源及其在染色体上的位置,对绵阳11×CH1302的F_1、F_2及F_(2∶3)家系进行了遗传分析,推断其抗白粉病基因可能来源于中间偃麦草,暂将其命名为PmCH1302。利用i Select 90K SNP芯片对抗、感病池进行扫描,发现位于2AL染色体上的多态性位点最多,为313个,占全部多态性位点的9.79%,且集中于2AL染色体100~105 c M和150~155 cM两个区域附近。在上述位点选取SSR标记,筛选出3对与Pm CH1302连锁的分子标记,Xwmc522、Xgwm356和Xgwm526,其中Xgwm356和Xgwm526位于Pm CH1302两侧,连锁距离分别为3.1 c M和7.8 cM。利用遗传图谱以及中国春缺体、双端体将PmCH1302定位于小麦2AL染色体上。进一步与位于2AL上的Pm4、Pm50比较发现,PmCH1302可能是位于2AL上的一个新基因或等位基因。     

普通小麦99-2439 中的白粉病抗性遗传

普通冬小麦品系99-2439在郑州连续4年对田间白粉菌(Blumeria graminis sp. tritici)表现高抗,但其抗性基因来源不清。通过染色体C-分带和1RS染色体特异性SCAR标记鉴定, 表明它是一个小麦-黑麦(Triticum aestivum - Secale cereale)1BL/1RS异易位系。通过对中国春×99-2439杂交F2代分离群 体抗性鉴定和1RS染色体臂检测结果分析, 证明该抗病基因不在1RS染色体臂上。用单孢小麦白粉菌分离株对其抗性遗传进行研究, 结果表明, 99-2439的白粉病抗性由一对小种专化、隐性抗病基因控制。由于携带Pm5a的Hope/8Cc对中国的21个小麦白粉菌分离菌株均高度感病, 而99-2439高抗混和白粉菌和5个单孢分离菌株, 所以, 99-2439所携带的抗白粉病基因不同于Pm5a。     

一粒小麦抗白粉病和条锈病基因的分析

一粒小麦是普通小麦抗性改良的宝贵资源.本研究对24份一粒小麦分别进行了白粉病和条锈病混合菌种苗期接种鉴定,进一步分别用一套白粉病菌菌株(15个)对2份乌拉尔图小麦和条锈病菌小种(21个)对1份栽培一粒小麦进行接种鉴定,其中乌拉尔图小麦UR206能抵抗所有供试白粉菌菌株,UR204除对白粉菌菌株E11感病外,对其余菌株表现抗性;栽培一粒小麦MO205对不同条锈菌小种表现出不同的抗性反应,研究表明乌拉尔图小麦UR206、UR204和栽培一粒小麦MO205分别含有与已知抗白粉病和抗条锈病基因不同的新基因.对乌拉尔图小麦UR204、UR206和栽培一粒小麦MO205分别进行抗白粉和条锈病基因的遗传分析,结果表明乌拉尔图小麦UR204和UR206分别含有一对显性抗白粉病基因,栽培一粒小麦MO205含有两对独立遗传的显性抗条锈病基因.     

普通小麦99-2439中的白粉病抗性遗传

普通冬小麦品系99-2439在郑州连续4年对田间白粉菌(Blumeria graminis sp.tritici)表现高抗,但其抗性基因来源不清.通过染色体C-分带和IRS染色体特异性SCAR标记鉴定,表明它是一个小麦-黑麦(Triticum aestivum-Secale cereale)lBL/1RS异易位系.通过对中国春×99-2439杂交F2代分离群体抗性鉴定和1RS染色体臂检测结果分析,证明该抗病基因不在1RS染色体臂上.用单孢小麦白粉菌分离株对其抗性遗传进行研究,结果表明,99-2439的白粉病抗性由一对小种专化、隐性抗病基因控制.由于携带Pm5a的Hope/8Cc对中国的21个小麦白粉菌分离菌株均高度感病,而99-2439高抗混和白粉菌和5个单孢分离菌株,所以,99-2439所携带的抗白粉病基因不同于Pm5a.     

来自西尔斯山羊草的抗小麦白粉病基因Pm57抗性丧失突变体的筛选与鉴定

小麦近缘种属来源的抗白粉病基因是培育小麦抗病品种,防治白粉病危害的最重要基因来源。Pm57是位于西尔斯山羊草2S^s#l染色体长臂上的一个外源基因,对小麦白粉病具有苗期和成株期广谱抗性。为了创制Pm57白粉病抗性丧失突变体,利用基于基因突变体的植物抗病基因克隆新兴技术分离Pm57基因,选用0.625%的甲基磺酸乙酯(EMS)对1万粒小麦-西尔斯山羊草Pm57易位系89(5)69种子进行了诱变处理,M1大田密播种植,收获了1598个M2可育株系。初步对其中300个M2株系进行苗期白粉病抗性接种鉴定,并利用2个Pm57基因特异分子标记X2L4g9P4/HaeⅢ和X284274及小麦全国区试品系DUS测试所用的42对SSR核心引物对Pm57抗性丧失突变体进行鉴定,筛选出来自27个M2株系的真实抗性丧失突变体70个,Pm57基因抗性丧失突变体频率达到9.0%。本研究所获得的白粉病抗性丧失突变体为Pm57基因的后续克隆与抗白粉病分子机理研究提供了重要的材料基础。     

抗白粉病小偃麦异代换系的细胞学和RAPD鉴定

利用细胞学和RAPD方法,对从长穗偃麦草与普通小麦复合杂交后代中选育的抗白粉病小麦种质系山农87074－526和山农87074－551进行了鉴定。结果表明,两种质系的根尖细胞染色体数目均为2n=42,花粉母细胞减数分裂中期I（PMC MI）染色体构型为2n=21Ⅱ;二者杂交F1 PMC MI染色体构型亦为2n=21Ⅱ,两种质系分别与小麦中国春的杂种F1 PMC MI染色体构型均为2n=20Ⅱ 2I,说明两种质系为相同的双体异代系。在苗期和成株期两种质系对白粉病15号菌种均表现免疫,其白粉病抗性为显性,并且来自长穗偃麦草,抗白粉病基因位于它们所含的偃麦草染色体上。从80个随机引物中,筛选出2个引物OPE13和OPH15能在两种质系中稳定地扩增出长穗偃麦草亲本的特异DNA片段。     

小麦新抗源CH5383抗条锈病基因的遗传分析及分子定位

CH5383是新育成的源于中间偃麦草的渗入系,对小麦条锈病和白粉病均表现免疫。为明确其抗性来源、遗传方式和抗病基因在染色体上的位置,将CH5383的系谱材料及其与高感条锈病品种(系)杂交的F1、F2和F2:3家系群体进行条锈病抗性鉴定。结果表明,CH5383对条锈病的抗性源于中间偃麦草,对条锈病生理小种CYR32的抗性由一对显性核基因控制,将此基因暂时命名为YrCH5383。从476对SSR引物中筛选到3对引物Xgwm108、Xbarc206和Xbarc77与抗病基因连锁,遗传距离分别是8.2 cM、10.7 cM和13.6 cM。根据这两对标记在染色体上的位置,将抗病基因定位到3B染色体的长臂上。3B染色体的长臂还未见有正式命名的抗条锈病基因的报道,推测YrCH5383可能是一个源于中间偃麦草的新抗条锈病基因。     

几个四倍体小麦-山羊草双二倍体及其部分亲本的抗小麦白粉病基因分析

用离体叶段接种方法鉴定了11个四倍体小麦一山羊草双二倍体、波斯小麦PS5、硬粒小麦DR147、5份山羊草、杂交高代材料Am9／莱州953*^2F5和(DR147／Ael4)／／莱州953*^2F4对20个具有不同毒力白粉菌株的抗谱。通过与含有已知抗病基因品种或品系的反应模式比较,推测Am9／莱州953*^2F5含有Pm4b,波斯小麦PS5含有Pm4b与一个未知抗病基因组合;(DR147／Ael4)／／莱州953*^2F4和硬粒小麦DR147含有Pm4a和一个未知抗病基因组合;尾状山羊草Ael4和小伞山羊草Y39抗所有白粉菌株,由于迄今还没有在尾状山羊草和小伞山羊草中鉴定出抗白粉病基因,推测这2份山羊草含有新的抗白粉病基因。除Am9外,在其它双二倍体中波斯小麦或硬粒小麦的抗性部分受到抑制。山羊草的抗性部分或完全量到抑制。     

Chromosomal Location and Comparative Genomics Analysis of Powdery Mildew Resistance Gene Pm51 in a Putative Wheat-Thinopyrum ponticum Introgression Line

Powdery mildew (PM) is a very destructive disease of wheat (Triticum aestivum L.). Wheat-Thinopyrum ponticum introgression line CH7086 was shown to possess powdery mildew resistance possibly originating from Th. ponticum. Genomic in situ hybridization and molecular characterization of the alien introgression failed to identify alien chromatin. To study the genetics of resistance, CH7086 was crossed with susceptible genotypes. Segregation in F₂ populations and F_2:3 lines tested with Chinese Bgt race E09 under controlled conditions indicated that CH7086 carries a single dominant gene for powdery mildew resistance. Fourteen SSR and EST-PCR markers linked with the locus were identified. The genetic distances between the locus and the two flanking markers were 1.5 and 3.2 cM, respectively. Based on the locations of the markers by nullisomic-tetrasomic and deletion lines of ‘Chinese Spring’, the resistance gene was located in deletion bin 2BL-0.89-1.00. Conserved orthologous marker analysis indicated that the genomic region flanking the resistance gene has a high level of collinearity to that of rice chromosome 4 and Brachypodium chromosome 5. Both resistance specificities and tests of allelism suggested the resistance gene in CH7086 was different from previously reported powdery mildew resistance genes on 2BL, and the gene was provisionally designated PmCH86. Molecular analysis of PmCH86 compared with other genes for resistance to Bgt in the 2BL-0.89-1.00 region suggested that PmCH86 may be a new PM resistance gene, and it was therefore designated as Pm51. The closely linked flanking markers could be useful in exploiting this putative wheat-Thinopyrum translocation line for rapid transfer of Pm51 to wheat breeding programs.     

Microsatellite markers linked to 2 powdery mildew resistance genes introgressed from Triticum carthlicum accession PS5 into common wheat.

Two dominant powdery mildew resistance genes introduced from Triticum carthlicum accession PS5 to common wheat were identified and tagged using microsatellite markers. The gene designated PmPS5A was placed on wheat chromosome 2AL and linked to the microsatellite marker Xgwm356 at a genetic distance of 10.2 cM. Based on the information of its origin, chromosome location, and reactions to 5 powdery mildew isolates, this gene could be a member of the complex Pm4 locus. The 2nd gene designated PmPS5B was located on wheat chromosome 2BL with 3 microsatellite markers mapping proximally to the gene: Xwmc317 at 1.1 cM; Xgwm111 at 2.2 cM; and Xgwm382 at 4.0 cM; and 1 marker, Xgwm526, mapping distally to the gene at a distance of 18.1 cM. Since this gene showed no linkage to the other 2 known powdery mildew resistance genes on wheat chromosome 2B, Pm6 and Pm26, we believe it is a novel powdery mildew resistance gene and propose to designate this gene as Pm33.     

Pm50: a new powdery mildew resistance gene in common wheat derived from cultivated emmer

Fungal diseases of wheat, including powdery mildew, cause significant crop, yield and quality losses throughout the world. Knowledge of the genetic basis of powdery mildew resistance will greatly support future efforts to develop and cultivate resistant cultivars. Studies were conducted on cultivated emmer-derived wheat line K2 to identify genes involved in powdery mildew resistance at the seedling and adult plant growth stages using a BC₁ doubled haploid population derived from a cross between K2 and susceptible cultivar Audace. A single gene was located distal to microsatellite marker Xgwm294 on the long arm of chromosome 2A. Quantitative trait loci (QTL) analysis indicated that the gene was also effective at the adult plant stage, explaining up to 79.0 % of the variation in the progeny. Comparison of genetic maps indicated that the resistance gene in K2 was different from Pm4, the only other formally named resistance gene located on chromosome 2AL, and PmHNK54, a gene derived from Chinese germplasm. The new gene was designated Pm50.     

Molecular mapping of a recessive powdery mildew resistance gene in spelt wheat cultivar Hubel

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most important wheat diseases worldwide. The basis for wheat powdery mildew resistance breeding consists of screening diversified host genetic resources with a range of races of the powdery mildew pathogen. Spelt wheat (Triticum aestivum ssp. spelta 2n = 6x = 42, AABBDD) is a close relative of common wheat (T. aestivum ssp. aestivum) and contains several known disease resistance genes, including Pm1d, Yr5, and Lr65. Here, we report the identification and mapping of a powdery mildew resistance gene in spelt wheat cultivar Hubel, which was introduced to China from Europe and is resistant to Chinese Bgt isolate E09 at the seedling stage. Genetic analysis of a recombinant inbred line population derived from a cross of Hubel and a susceptible early maturing mutant line indicated that Hubel possessed a recessive powdery mildew resistance gene (temporarily designated MlHubel). Markers linked to MlHubel were identified using bulked segregant analysis, simple sequence repeat, and expressed sequence tag-derived sequence tagged site methods. The linked markers were physically located on wheat chromosome 2D. Comparative genomic analysis indicated that the genetic interval covering MlHubel in wheat is highly colinear with the corresponding regions on Brachypodium distachyon chromosome 5 and Oryza sativa chromosome 4. Accordingly, the genetic map of MlHubel was established in comparison with B. distachyon 5L and O. sativa 4L, with the closest marker Xgwm265 being 0.4 cM from MlHubel. The identification of the recessive powdery mildew gene in spelt wheat suggests the potential of this accession along with its closely linked markers in breeding for resistance to powdery mildew.     

Identification and mapping of a new powdery mildew resistance gene on chromosome 6D of common wheat

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most serious wheat diseases. The rapid evolution of the pathogen's virulence, due to the heavy use of resistance genes, necessitates the expansion of resistance gene diversity. The common wheat line D57 is highly resistant to powdery mildew. A genetic analysis using an F(2) population derived from the cross of D57 with the susceptible cultivar Yangmai 158 and the derived F(2:3) lines indicated that D57 carries two dominant powdery mildew resistance genes. Based on mapping information of polymorphic markers identified by bulk segregant analysis, these two genes were assigned to chromosomes 5DS and 6DS. Using the F(2:3) lines that segregated in a single-gene mode, closely linked PCR-based markers were identified for both genes, and their chromosome assignments were confirmed through linkage mapping. The gene on chromosome 5DS was flanked by Xgwm205 and Xmag6176, with a genetic distance of 8.3 cM and 2.8 cM, respectively. This gene was 3.3 cM from a locus mapped by the STS marker MAG6137, converted from the RFLP marker BCD1871, which was 3.5 cM from Pm2. An evaluation with 15 pathogen isolates indicated that this gene and Pm2 were similar in their resistance spectra. The gene on chromosome 6DS was flanked by co-segregating Xcfd80 and Xmag6139 on one side and Xmag6140 on the other, with a genetic distance of 0.7 cM and 2.7 cM, respectively. This is the first powdery mildew resistance gene identified on chromosome 6DS, and plants that carried this gene were highly resistant to all of the 15 tested pathogen isolates. This gene was designated Pm45. The new resistance gene in D57 could easily be transferred to elite cultivars due to its common wheat origin and the availability of closely linked molecular markers.     

威岭栽培黑麦抗白粉病特性导入小麦的研究

威岭黑麦(Weiling rye)是一个高抗白粉病(Erysiphe gramininis f．sp．tritici)的中国矮杆栽培黑麦。以Weiling rye作为白粉病抗源,高感白粉病小麦栽培品种My8443为母本,从Weiling rye与小麦My8443远缘杂交的BC_2F_6后代中鉴定出一个新的小麦-黑麦易位系No．147,以实现威岭黑麦白粉病抗性向普通栽培小麦的转移。No．147及其亲本的抗白粉病特性通过苗期和成株期优势生理小种混合接种和室内单生理小种接种鉴定,改良的染色体C-分带和基因组原位杂交技术(GISH。Ge- nomic in situ hybridization)被用于鉴定小麦和黑麦的染色质,酸性聚丙烯酰胺凝胶电泳(APAGE)被用于鉴定黑麦醇溶蛋白1RS特异条带,11个黑麦种属特异性标记SCM(Secale cereale marker)引物被用于扩增分析黑麦特异性简单重复序列(SSR)。研究结果证实No．147是一个新的高抗白粉病的1BL/1RS小麦-黑麦染色体易位系,并对其产生的细胞学机制进行了分析。论文对中国栽培黑麦抗性基因资源的利用和该易位系在小麦遗传育种改良中的利用价值进行了讨论。