Detection of downy and powdery mildew resistance QTL in a ‘Regent’ × ‘RedGlobe’ population

One hundred and eighty six F₁ plants from a ‘Regent’ × ‘RedGlobe’ cross were used to generate a partial linkage map with 139 microsatellite markers spanning all 19 chromosomes. Phenotypic scores for downy mildew, taken over two years, confirmed a major resistance QTL (Rpv3) against downy mildew in the interval VVIN16-cjvh to UDV108 on chromosome 18 of ‘Regent’. This locus explained up to 62 % of the phenotypic variance observed. Additionally a putative minor downy mildew resistance locus was observed on chromosome 1 in one season. A major resistance locus against powdery mildew (Ren3) was also identified on chromosome 15 of ‘Regent’ in the interval UDV116 to VChr15CenGen06. This study established the efficacy of and validated the ‘Regent’-derived downy and powdery mildew major resistance genes/QTL under South African conditions. Closely linked SSR markers for marker-assisted selection and gene pyramiding strategies were identified.     

QTLs for barley yield adaptation to Mediterranean environments in the ‘Nure’ × ‘Tremois’ biparental population

Multi-environment trials represent a highly valuable tool for the identification of the genetic bases of crop yield potential and stress adaptation. A Diversity Array Technology^®-based barley map has been developed in the ‘Nure’ × ‘Tremois’ biparental Doubled Haploid population, harbouring the genomic position of a gene set with a putative role in the regulation of flowering time and abiotic stress response in barley. The population has been evaluated in eighteen location-by-year combinations across the Mediterranean basin. QTL mapping identified several genomic regions responsible for barley adaptation to Mediterranean conditions in terms of phenology, grain yield and yield component traits. The most frequently detected yield QTL had the early flowering HvCEN_EPS2 locus (chromosome 2H) as peak marker, showing a positive effect from the early winter parent ‘Nure’ in eight field trials, and explaining up to 45.8 % of the observed variance for grain yield. The HvBM5A_VRN-H1 locus on chromosome 5H and the genomic region possibly corresponding to PPD-H2 on chromosome 1H were significantly associated to grain yield in five and three locations, respectively. Environment-specific QTLs for grain yield, and clusters of yield component QTLs not related to phenology and or developmental genes (e.g. on chromosome 4H, BIN_09) were observed as well. The results of this work provide a valuable source of knowledge and tools for both explaining the genetic bases of barley yield adaptation across the Mediterranean basin, and using QTL-associated markers for MAS pre-breeding and breeding programmes.     

Partial self-compatibility in ‘Tombul’ and ‘Montebello’ hazelnuts

Summary Self-pollination of hazelnut (Corylus avellana L.) cultivars in 1988 and 1990 revealed the existence of partial self-compatibility in Tombul and Montebello. Percent cluster set in these cultivars averaged 44 and 20%, respectively, but was less than 10% in 8 other cultivars investigated. Percent cluster set from pollination with Segorbe averaged 62 and 41% in 1988 and 1990, respectively. Self-pollination produced 40% fewer nuts per cluster and twice as many blanks as cross-pollination. All cultivars and selections have an active sporophytic incompatibility system.Evaluation of self-compatibility in seedlings from the cross Montebello × Compton revealed that the partial self-compatibility of the maternal parent was transmitted to some of the progeny. Self-pollination resulted in greater than 10% cluster set in two selections, OSU 41.134 and OSU 43.025, in both years, but only in 1988 in OSU 42.089 and Willamette. Three other selections had very low set in both years. Results of incompatible crosses with standard testers were generally in agreement with those of self-pollination, except that the S₂ tester induced greater set on 3 genotypes in 1988 and the S1 tester on 2 genotypes in 1990 than self-pollination. The partial self-compatibility of Montebello, OSU 41.134, and OSU 43.025 appears to be due to a failure of their stigmas to prohibit pollen tube growth in incompatible crosses. There is no evidence of a pollen-part mutation in Montebello, nor is there evidence that partial self-compatibility is due to the interaction of S-alleles, as Barcelona, which has the same alleles as these three genotypes, failed to set nuts in all incompatible crosses.     

‘荷’你‘藕’遇

正七八月是赏荷的季节。打开互联网,随意一搜,全国各地的荷展就超过百个,但是今年顶级的荷展在江苏扬州。7月28日上午,第30届全国荷花展在扬州瘦西湖风景区开幕,全国27个省市近400名业内专家齐聚于此,共同感受"一水回环杨柳外,画船往来藕花天"的荷之盛宴。全国政协人口资源环境委员会副主任、     

Construction of ‘compound’ rust resistance genes in maize

Summary The Rp1 locus of maize is a complex rust resistance locus where multiple resistance genes are clustered. Rare recombination events between Rp1 genes or alleles can produce two or more detectable genes linked in coupling phase. Such compound genes can then be manipulated as a single gene in breeding programs. Several compound Rp1 genes, each carrying two or three tightly linked resistance genes, were constructed to test their utility in controlling common rust. While none of the lines carrying single Rp1 genes were resistant to all of the characterized North American P. sorghi biotypes, most of the two component and all of the three component Rp1 complexes were resistant. The potential for utilization of compound resistance genes in other crop species is discussed.     

Integrated ethylene and temperature conditioning for induction of ripening capacity in ‘Anjou’ and ‘Comice’ pears

‘Anjou’ and ‘Comice’ pears from three harvest dates were conditioned to develop ripening capacity by exposure to 100 μL L⁻¹ ethylene at 20 °C for 0, 24, 48, or 72 h, followed by varying durations of temperature conditioning at −0.5 or 10 °C. Ripening capacity was tested by measuring fruit firmness after 7 d at 20 °C after completion of conditioning treatments. Fruit firmness was also measured after conditioning but before ripening, and was designated “shipping firmness”, indicative of the potential for the fruit to withstand transport conditions without physical injury. Ripening capacity in both cultivars developed more rapidly with later harvest date, increasing duration of ethylene conditioning, and increasing duration of temperature conditioning. Ripening capacity developed much more rapidly at 10 °C than at −0.5 °C. Useful durations of temperature conditioning at 10 °C were limited by fruit softening below acceptable values of shipping firmness. However, sequential combinations of ethylene and temperature conditioning at both −0.5 and 10 °C were identified wherein post-conditioning shipping firmness was acceptable.     

‘罗宾娜’有望替代‘元帅’成畅销品种

今年以来，昆明斗南花卉批发市场上的百合品种结构出现了新变化，继今年1月份起亚洲百合退出大宗市场外，最近一段时间，已种植10余年的红色代表品种‘元帅’出现隐退迹象，“OT”系列百合品种‘罗宾娜’取而代之，其产量逐渐增加，价格居高不下，有望成为今后红色系的代表品种而畅销国内外市场。     

康乃馨新秀‘红色恋人’力压‘达拉斯’

母亲节前后昆明斗南花市康乃馨日上市量猛增至1200万支，均价也从4月份的0．33元／支涨至0．60元／支，其中红色系列（挑红色、红色）品种最为畅销，均价为0．70元／支。红色系主打品种‘达拉斯’（‘Dallas’）无论是规模还是价格日渐衰落，而其相似品种‘红色恋人’（‘Bombay’），上市量飙升，价格居高不下，成为康乃馨新秀。     

切花红掌‘热情’‘火焰’的综合比较

最早进入中国市场的切花红掌几乎都是红色，如今市场上红色系品种比例下降了不少，但仍然是最主要的色系。     

年年岁岁‘月月红’

‘月月红’是月季大家族中最普通的一种。它没有牡丹的雍容华贵,也不像杜鹃、茶花那样绚丽多彩。然而‘月月红’名符其实,几乎月月都能开出小小的粉红色花朵,平凡而好养,也因此赢得了大家的厚爱。公园里、草地边、人行道旁、庭院里、阳台上……从城市到乡村,到处可看到它可爱的身影。我对‘月月红’十分钟爱。20多年前,我养的第一盆花就是友人送的‘月月红’。图1是它的第五代扦插苗长大后的样子。这些年的养植,颇有一些体会。‘月月红’适宜生长在阳光充足、空气流通的环境中,喜欢疏松肥沃、排水良好的中性或微酸性土壤。植株壮实而根     

兜兰‘魔帝’和‘肉饼’栽培管理

<正>兜兰又称拖鞋兰、仙履兰,是兰科兜兰属植物的统称,多数为地生种,杂交品种较多,多年生草本。兜兰喜温暖、湿润和半阴的环境,怕强光暴晒。绿叶品种生长适温为12℃～18℃,斑叶品种生长适温为15℃～25℃,能忍受的最高温度约30℃,越冬温度应在10℃～15℃为宜。一般而言,温暖型的斑叶品种等大多在夏秋季开花,冷凉型的绿叶品种在冬春季开花。主要分布于印度、尼泊尔、缅甸、泰国、越南、菲律宾、马来西亚、     

Histogenic layer manipulation in chimeral ‘Thornless Evergreen’ trailing blackberry

Summary Thornless Evergreen blackberry (Rubus laciniatus Willd.) is a periclinal chimera in which the epidermis has mutated to a thornless phenotype while the internal portions of the plant possess the wild thorny genotype. Shoot tips were used to establish a source of experimental material. Nine hundred plants of Thornless Evergreen were proliferated and rooted in vitro in an effort to locate a chimeral rearrangement and/or a pure thornless plant. When these tissue culture propagated plants were grown in the greenhouse, two predominant plant types were observed; about 53% of the propagules showed a normal vining growth habit while the other 47% of the plants were dwarfed due to shortened internodes. Adventitious shoots from isolated root segments of the normal plants were thorny, while those from many of the dwarfed plants had developed from epidermal cells of the parent. Such plants of epidermal origin are no longer chimeral but are of pure thornless genotype.Graduate Assistant and Associate Professor, respectively. Funds for this research were provided by the Illinois Expreiment Station. We thank Mel Chu and Alan Otterbacher for technical assistance.     

Dynamics of ascorbic acid in ‘Braeburn’ and ‘Gala’ apples during on-tree development and storage in atmospheres conducive to internal browning development

The underlying causes as well as chemical and biochemical alleviation for CO₂-induced browning in apple fruit are poorly understood. Ascorbic acid (AsA) dynamics in ‘Braeburn,’ a susceptible cultivar, and ‘Gala’, a resistant cultivar, were evaluated during on-tree development and storage at 0.5 °C in air or controlled atmospheres (CA) containing 1 kPa O₂ and 1, 3 or 5 kPa CO₂. ‘Braeburn’ fruit treated with diphenylamine (DPA) was also stored for 1 month to determine effects on browning incidence and AsA concentration. ‘Braeburn’ apples had significantly higher (p ≤ 0.05) AsA levels than ‘Gala’ during on-tree development, and storage. No correlation between AsA and maturity/ripening indices for ‘Braeburn’ or ‘Gala’ was apparent. Histochemical localization of fruit AsA showed a staining intensity consistent with the quantity analytically determined, and showed that AsA is diffusely distributed throughout the cortex in both cultivars during on-tree development. During storage, AsA was localized to the periphery of brown tissue in ‘Braeburn’ and to the coreline and cortex proximal to the peel in ‘Braeburn’ and ‘Gala’ tissues. DPA decreased browning development during storage, however, no correlation between DPA treatment and AsA quantity in healthy or brown cortex tissue was observed. The results indicate AsA quantity alone is not an indicator of CO₂ sensitivity in these two cultivars.     

Comparative genetic analysis of field resistance to downy mildew in the lettuce cultivars ‘Grand Rapids’ and ‘Iceberg’

Downy mildew on lettuce is currently controlled using host resistance genes (Dm genes) that confer race-specific resistance in seedlings. Field resistance (FR) that is active in adult plants but not seedlings was identified in the cvs. Grand Rapids and Iceberg. The goal of our study was to evaluate the utility of Grand Rapids as a source of novel Bremia resistance alleles, particularly in comparison with Iceberg. To measure FR, downy mildew symptoms were evaluated following natural infection in field experiments. The responses of Grand Rapids and Iceberg were similar in many respects. Although both cultivars had a small percentage of plants exhibiting disease symptoms, the average disease ratings were as low as for cultivars with effective Dm genes. We observed no evidence for race specificity. FR was effective over 3 years of our study, despite documented variation within pathogen populations. Both cultivars lacked all known seedling resistance genes except Dm13, which was not responsible for the resistance observed in field experiments. Similar segregation of FR was observed in F₂ populations for both Grand Rapids and Iceberg. The presence of highly susceptible families within Grand Rapids × Iceberg populations suggested the presence of at least one unique resistance allele in each cultivar. Preliminary genetic analysis of FR from Grand Rapids revealed a high estimate of narrow-sense heritability that suggested simple inheritance, but single gene models did not fit the observed data. Our results suggest that Grand Rapids may represent an underutilized resource for controlling downy mildew in lettuce.     

The effect of in vivo and in vitro applications of ethrel and GA<Subscript>3</Subscript> on sex expression in bitter melon (<Emphasis Type="Italic">Momordica charantia</Emphasis> L.)

Bitter melon (Momordica Charantia L.) is an important vegetable crop with nutritional and medicinal qualities. As a member of cucurbitaceae it is monoecious with varying proportions of staminate and pistillate flowers. This study was undertaken to determine the effects of various applications of ethrel and gibberellic acid (GA₃) on sex modification in M. charantia. In the first set of experiments, various concentrations of hormones were added to the seed germination medium, in the second, adult plants growing in the field were sprayed with aqueous solutions of ethrel or GA₃ three times at three-day intervals. The number and sex of open flowers was recorded daily for 60 days after the first flower opened and total number of staminate and pistillate flowers was calculated at the end of the experiment. The highest frequency (29.5%) of pistillate flowers was observed in plants treated with 500 ppm ethrel at germination. Similarly, spraying of adult plants with 100 ppm GA₃ increased the proportion of pistillate flowers to 26% relative to 15% in untreated controls. Both ethrel and GA₃ induced significantly higher number of pistillate flowers than control. In vitro hormone application during seed germination was much more successful than spraying of field grown plants.     

Heritability of thrips resistance in the ‘IPA-3’ onion cultivar in South Texas

A two season study was conducted to compare the onion cultivars TG1015Y and IPA-3 for resistance to thrips in South Texas. Narrow and broad sense heritabilities were estimated from populations developed from the cross, ‘IPA-3’ × ‘TG1015Y’. Parents, F1, F2, and the respective backcross populations were evaluated for thrips numbers at the Texas Agricultural Experiment Station, Weslaco, TX. ‘IPA-3’ had significantly fewer thrips than ‘TG1015Y’ in both seasons. Yield was significantly different only in the 1996–97 season. The heritability of thrips resistance in this study was very low. Depending on the methods of estimation h ² was 5.3% and 4.0%, and H ² was 4.1% and 8.0%. These results suggest that greater genetic gains for thrips resistance in onion can be achieved by selection on a family basis rather than using single plant selection. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of endosperm development of allotriploid × diploid/tetraploid crosses in <Emphasis Type="Italic">Lilium</Emphasis>

Lilium are Fritillaria-type plants. Triploid lilies, regardless of their male sterility, can be used as female parents to cross with appropriate males, in contrast to other triploid Polygonum-type plants, which are usually seedless. Up to now, however, little attention has been paid to the reason. Here we made allotriploid × diploid/tetraploid crosses in Lilium. Endosperm and progenies of LAA × AA/AAAA crosses were analyzed for ploidy level and genome composition. The endosperm of some LAA × AA/AAAA ovules developed well but there was little or no development of LAA × LL/OO endosperm. The endosperm genome composition of LAA × AA, LAA × AAAA, LAA × LL, LAA × OO are theoretically derived as 5A + 2L, 6A + 2L, 4A + 3L, 4A + 2L + O, respectively. Genomic in situ hybridization showed that the progenies of LAA × AA/AAAA were aneuploid. Based on the experimental results and analyses, our hypothesis is that five same genomes of endosperms are essential for its development in triploid × diploid/tetraploid crosses of Lilium. The hypothesis can explain the success or failure of 3x × 2x/4x crosses in Lilium and is of importance for lily breeders who need to know the likelihood of success when producing new cultivars of this economically important horticultural crop.     

‘红运’玉兰繁育

<正>‘红运’玉兰属木兰科木兰属玉兰亚属,是20世纪80年代科研人员从‘二乔’玉兰的自然芽变枝历经10代无性繁殖,选育出的性能稳定的玉兰新品种。‘红运’玉兰花色艳丽怡人、馥郁清香,在南方和其他的玉兰相比,‘红运’玉兰一年春、夏、秋三次开花。‘红运’玉兰孤植或丛植都很美观,树形婀娜,枝繁花茂,是优良的庭园、街道绿化植物,特别是盛夏木本花卉稀少的季节,盛开的‘红运’玉兰可弥补其他木本花木的不足,是极具观赏价值的园林树种。‘     

‘自由人’槭栽培技术

<正>‘自由人’槭是红花槭和银白槭杂交系中最出色的改良品种,不仅继承了红花槭的优异观赏性,而且继承了银白槭的广泛适应性,生长速度快,是引进观赏树种中不可多得的优良品种。‘