The introduction into bread wheat of a major gene for resistance to powdery mildew from wild emmer wheat

Summary A new source of resistance to wheat powdery mildew caused by Erysiphe graminis has been transferred to hexaploid bread wheat, Triticum aestivum, from the wild tetraploid wheat, Triticum dicoccoides. The donor was crossed to bread wheat and the pentaploid progeny was then self-pollinated. Plants having a near stable hexaploid chromosome complement were selected in the F₃ progeny and topcrossing and backcrossing of these to a second wheat cultivar to improve the phenotype was undertaken. Monosomic analysis of early backcross lines showed the transferred gene to be located on chromosome 4A. The gene has been designated Pm16.     

The inheritance of resistance to powdery mildew in interspecific hybrids and induced amphiploids of Zinnia elegans Jacq. and Z. angustifolia HBK

Summary Sterile interspecific hybrids and colchicine-induced amphiploids of Zinnia elegans Jacq. and Z. angustifolia HBK were examined to determine the mode of inheritance of resistance to Erysiphe cichoracearum DC ex Merat. Fertility was restored through colchicine treatment of two sterile hybrids of species reciprocal parentage which differed in ray petal response to the pathogen. Derived amphiploids were subsequently intercrossed to overcome the lack of segregation for this trait due to genetic control of pairing upon chromosome doubling. Resistance to E. cichoracearum appears to be complexly inherited in both leaves and ray florets of sterile hybrids and induced amphiploids. Two major dominant genes have been implicated in conferring resistance in ray petal tissue of derived amphiploids. Data obtained from the F₁ hybrid progeny of the intercrossed amphiploids indicate that this trait is not cytoplasmically inherited. It is speculated that the genes conferring resistance in the ray florets are acting independently from those controlling leaf resistance and that most, if not all, of the resistance genes are inherited from Z. angustifolia.Scientific Article No. A-3825, Contribution No. 6804 of the Maryland Agricultural Experiment Station.     

微波法提取水红花子总黄酮的应用研究

在微波单因素提取的基础上,采取L9(33)正交优化试验,探讨乙醇浓度、微波提取时间和料液比对水红花子总黄酮提取率的影响。结果表明,微波提取法影响水红花子总黄酮提取率的主要因素为料液比,其次为乙醇浓度、提取时间。在微波功率为350W的条件下,最佳提取工艺条件为:乙醇体积分数为80%,微波提取时间为90s,料液比(g∶mL)为1∶25。在此条件下,水红花子总黄酮提取率可达5.05%。     

RAPD and SCAR markers for powdery mildew resistance gene er in pea

In pea, a single recessive gene (er) on linkage group 6 confers resistance to powdery mildew caused by Erysiphe pisi. The present study aims to identify molecular markers linked to the er gene. Screening of the powdery mildew‐resistant cultivar ‘DMR11’ and its susceptible nearisogenic line for polymorphism revealed linkage of two RAPD primers (OPO‐02 and OPU‐17) to the er gene and a sequence characterized polymorphic region (SCAR) primer, ScOPD‐10₆₅₀ with er in a population of 83 F₂ plants in the order: OPU‐17 ‐ er ‐ ScOPD‐10₆₅₀ ‐ OPO‐02. The markers ScOPD‐10₆₅₀ and OPU‐17 being coupled with the allele causing resistance would substantially increase the efficiency of marker‐assisted selection in peabreeding for powdery mildew.     

乌鲁木齐三角荨麻白粉病菌鉴定和进化分析

通过显微观察和核糖体DNA转录间隔区( ITS)序列分析对引起乌鲁木齐地区三角荨麻白粉病的病原进行了鉴定。病原菌的分生孢子梗顶端产生一个椭圆形的分生孢子,分生孢子(18.75~23.75)μm ×(31.25~43.75)μm;黑褐色、球形的闭囊壳嵌在叶表面的菌丝体中,直径为87.5~143.75μm;每个闭囊壳中有6或8个子囊,子囊无柄,大小为(25~43.75)μm ×(37.5~68.75)μm,每个子囊中有4或5个子囊孢子,每个子囊孢子(18.75~21.88)μm ×(25~31.25)μm。采用真菌ITS通用引物,扩增病菌rDNA ITS,测序及进化分析后发现,其ITS序列与伊朗异株荨麻白粉病菌(登录号AB104524)的同源性为99%,而且聚在一个进化支上。结果表明,乌鲁木齐三角荨麻白粉病菌属于Erysiphe urticae,与伊朗异株荨麻白粉病菌亲缘关系最近。     

Evaluation of parsley for resistance to the pathogens Alternaria radicina, Erysiphe heraclei, Fusarium oxysporum, and celery mosaic virus (CeMV)

Resistance tests of 127 parsley accessions (Petroselinum crispum) were carried out during 2 years of field investigations involving natural infection for black leaf spot (Alternaria radicina), mildew (Erysiphe heraclei), leaf chlorosis (Fusarium oxysporum) and viruses, particularly celery mosaic virus (CeMV). In this first extensive evaluation of parsley for all tested pathogens accessions were found to be free of symptoms. Varieties of vars. crispum and tuberosum contained more accessions weakly infected or immune to black leaf spot than vars. vulgare and neapolitanicum. In a separate test five var. crispum accessions showed significantly reduced disease ratings, indicating their potential as sources of resistance. Mildew attacked almost the same number of accessions in both years: 29 accessions of var. crispum showed no symptoms, but 16 of the var. tuberosum accessions were highly susceptible. Whereas in the var. vulgare one half of the introductions were moderately or strongly infected by viruses, mainly CeMV, a high number of plants remained uninfected in the vars. crispum, neapolitanicum and tuberosum. In the case of F. oxysporum, the greatest amount of infection was in the var. crispum during both years. The sources of resistance described including multiple resistance would be of interest in future breeding programmes for resistance to the parsley pathogens discussed.     

Development of SCAR markers linked to the Pm21 gene conferring resistance to powdery mildew in common wheat

Powdery mildew is an important disease in most of the wheat production areas of the world. The resistance gene Pm21 (6AL/6VS trans-location) derived from Haynaldia villosa confers resistance to all available isolates of Erysiphe (Blumeria) graminis f. sp. tritici in China and Europe. The objective of this study was to develop fast and reliable sequence characterized amplified region (SCAR) markers linked to the Pm21 gene. A random amplified polymorphic DNA (RAPD) marker for Pm21, OPH17₁₄₀₀, was converted to SCAR markers after sequencing the two ends of the polymorphic DNA fragment. Two SCAR markers, SCAR₁₂₆₅ and SCAR₁₄₀₀, were developed to detect the Pm21 gene in different genetic backgrounds. The specific SCAR₁₂₆₅ marker enable large-scale accurate screening for the presence/absence of Pm21 allele.     

New sources of nonspecific resistance to rust and common bacterial blight in dry bean landrace Pompadour

Summary Inheritance of resistance of five melon lines to two strains of Sphaerotheca fuliginea belonging to races 1 (Sf1) and 2 (Sf2) and to one strain of Erysiphe cichoracearum (Ec) have been studied. PMR 45 possesses one dominant gene controlling only Sf1. WMR 29 has one dominant gene for resistance to Sf1 and another for Sf2 and these genes seem to be linked. In line PMR 5, one dominant gene (or a group of three closely linked genes) is involved in the control of the three strains with one complementary gene for Sf1 and another one for Ec. PI 124112 has one dominant gene or two closely linked loci controlling Sf1 and Sf2 and two complementary different genes controlling Ec. Nantais Oblong has one dominant gene controlling only Ec. A nomenclature of the genes described is proposed.     

Multigene Families of Powdery Mildew Resistance Genes in Locus Mla on Barley Chromosome 5

A review of data on powdery mildew resistance genes in the Mla locus of barley reveals that there are at least 12 clusters of genes present, each comprising one Mla gene and one or more closely linked, additional resistance genes. Tentative designations are listed for 16 additional resistance genes. Many sources of powdery mildew resistance in barley appear to harbour multigene families in the Mla region, not single ‘superior’genes.