Pollen Characteristics and Genetics of Induced and Spontaneous Genetic Male-Sterile Mutants in Rice

Pollen characteristics, inheritance and allelism of 23 genetic male-sterile (ms) mutants of rice (Oryza sativa L.) were investigated. Ten of the mutants were induced by ethyl methane sulfonate, one induced by ethyleneimine, seven induced by gamma rays, one induced by streptomycin, one derived from tissue culture and three were spontaneous mutants found in the field. Four pollen abortion types were observed among these ms mutants: 3 no-pollen (NP) type, 6 complete pollen abortion (CPA) type, 13 partial pollen abortion (PPA) type, and 1 stainable pollen abortion (SPA) type. Progeny tests over two years indicated that each of the mutants was inherited as a monogenic recessive. A partial diallel cross among the 23 ms mutants indicated that mutant E2 was allelic to G4, E5 was allelic to E9, N2 was allelic to N3, and that three other mutants, E3, G6 and T1, shared the same ms locus. Gene symbols ms-46 (t) through ms-63 (t) were assigned to these mutants.     

Selection for Non-Shattering Common Vetch, Vicia sativa L.

Loss of seeds from mature pods is common in Vicia sativa L., an important annual, resown forage legume in West Asia and North Africa. Pod shattering restricts its use as a leguminous forage crop. This paper reports the results of germplasm evaluation for non-shattering pods and of breeding and selection to improve seed retention. Wide variation in pod-shattering exists between common vetch ecotypes collected from different regions. Three wild mutants with almost completely non-shattering pods were identified and isolated for use as a genetic resource in cross breeding programmes. Genetic studies revealed that the non-shattering character in the wild types of common vetch is due to a simple recessive gene, whereas shattering in the cultivated types is due to an allelic dominant pair of genes. Incorporation of the non-shattering gene into agronomically-promising lines was achieved by back-crossing. Lines having an average of 95—97 % non-shattering pods were obtained, as compared to 40—50 % in the original cultivated lines which represents a major agronomic advance in common vetch breeding. The importance of seed retention to the economics of seed production is discussed.     

Interactions between plant and aphid genotypes in resistance of lettuce to Myzus persicae and Macrosiphum euphorbiae

Summary Six lettuce lines, representing two types of resistance to the green peach aphid, Myzus persicae, and a control line with high susceptibility to M. persicae were tested for resistance to six different clones of Myzus persicae and two clones of the potato aphid, Macrosiphum euphorbiae.The clones of M. persicae showed very different levels of aggressiveness on lettuce: two had a high level of reproduction, two had an intermediate level and two were poorly adapted to lettuce as a host. Differences between lettuce lines in aphid reproduction increased with increasing aggressiveness of the aphid clone, which means that aggressive clones are most effective for selection purposes. No evidence was found for clone-specific plant genotype reactions, meaning that lines resistant to one clone will also be resistant to other clones of M. persicae, allthough not neccessarily at the same level. The lettuce lines selected for partial resistance to the aggressive clone WMp1 were completely or almost completely resistant to less aggresive clones.No differences in level of reproduction were found between the two clones of M. euphorbiae and no relation was observed between resistance to M. persicae and M. euphorbiae, indicating the species-specific character of resistance to leaf aphids in lettuce.     

Genetic Analysis of Resistance to Green Leafhopper in Rice

The inheritance of resistance to green leafhopper, Nephotettix impicticeps Ichi, was studied in 11 cultivars of rice, Oryza saliva L. These resistant cultivars were crossed with the susceptible cultivar ‘TN1’. The materials consisted of F₁, F₂ and F₃ populations including parents which were assessed by the bulk screening test. It was found that resistance in the cultivars TR36′, UPR254-35-3′-2′, ‘Jhingasail’, ‘Govind’, ‘RP825-45-1-3’, ‘MRC603-303’, ‘RD4’, and ‘Irat104 ’ was conditioned by a single dominant gene, whereas resistance in ‘Ptb8’ IR9805-97-1′, and ‘BG367-7’ was controlled by one recessive gene. The test on the allelic relationships of the resistance genes in the test cultivars with the known genes Glb1 and Glb2 revealed that the single dominant gene that conveyed the resistance in ‘UPR254-35-3-2’ and ‘Jhingasail’ was allelic to Glh1 and segregated independently of Glh2. The resistance in ‘Govind’ and ‘RP82S-45-1-3’ was governed by the Glh2 gene which was independent of Glh1. The test cultivars ‘IR36’;. ‘MRC603-303’, ‘RD4’. and Irat104 ’ had a dominant gene for resistance which was nonallelic to Glb1 and Glb2. The recessive gene which conditioned the resistance in ‘Ptb8’, ‘IR9805-97-1’, and ‘BG367-1’ segregated independently of Glh1 and Glh2. Eleven trisomics in an ‘TR36’ background were crossed with ‘Java’, a cultivar susceptible to green leafhopper. The segregation pattern of the F₂ and backcross generations revealed that the Glb6 gene was located on chromosome 5.     

Novel pathotypes of lettuce mosaic virus — breakdown of a durable resistance?

Summary Resistance to lettuce mosaic virus (LMV) is derived either from cv. Gallega (g gene) or the wild accession PI251245 (mo gene). Previous studies indicated that these two genes were identical. Breeders in Europe produced numerous resistant cultivars utilisingg while in the USAmo was used. The resistance has been effective for over 20 years. However, recently there have been reports of LMV isolates causing unusually severe and sometimes necrotic symptoms on cultivars with these resistance genes. Investigations of these severe isolates have distinguished three new pathotypes in addition to the common pathotype (II) and identified a novel dominant gene for resistance. Themo/g genes confer resistance to pathotypes I and II but pathotype III possesses virulence for cultivars withg but not for those withmo. These two genes are therefore not identical but are probably either closely linked genes or alleles. Pathotype IV possesses virulence for all lettuce lines so far tested. Some isolates of this pathotype are seed transmitted in cultivars possessingmo org and have caused severe crop losses in southern France. The durability of the resistance conditioned by these two genes is discussed.     

Genetic Analysis of Resistance to Xanthomonas campestris pv. oryzae (Ishiyama) Dye in a Rice Breeding Line ARC 10464

The genetics of resistance to three Indian pathotypes of Xanthomonas campestris pv. oryzae, namely, IX01, IX08 and IX09, was studied in a landrace of Indica rice ‘ARC 10464’. Resistance to each of the two pathotypes IX01 and IX09 was governed by two independently-inherited dominant genes while a single dominant gene was operative against patho-type 1X08. The joint segregation tests conducted on F₂ plant progenies (F₃ families) using pathotypes IX01, IX08 and IX09 suggested that the gene/(s) effective against each of the pathotypes are different.     

Determination of vc and mating types of Cryphonectria parasitica isolates by multiplex PCR and their genetic diversity in 13 chestnut-growing provinces of Turkey

Vegetative compatibility (vc) and mating types and genetic diversity of Cryphonectria parasitica isolates were determined using 183 isolates obtained from 215 infected chestnut trees growing in 13 provinces of Turkey. Based on the cultural aspects, 143 of these isolates were evaluated as virulent whereas the remaining 40 isolates were hypovirulent. When vc types of 183 isolates were classically differentiated, 135 of them matched to EU-1 (82.3%), 29 of them to EU-12 (17.6%) vc type, whereas 19 of them did not match to the two. When molecular vic markers were used, all the isolates were assigned to two EU vc types; 149 to EU-1 (81.4%) and 34 (18.5%) to EU-12. Of the majority of the isolates, 134 (73.2%) had mating-type MAT-1, while 44 (24%) isolates had MAT-2 and 5 (2.8%) isolates had both mating types. The population analysis based on two DNA marker systems, Inter-Primer Binding Site and Start Codon Targeted Polymorphism, showed no intraspecific genetic variation among the C. parasitica isolates. The prevalence of two dominant vc types revealed by this study shows that biological control with hypovirulent EU-1 and EU-12 isolates will be significant for the country. The results might be helpful to chestnut breeders carrying out resistance breeding studies to manage this disease based on hypovirulence attributed to Cryphonectria hypovirus 1.     

紫花苜蓿非秋眠型标准品种种子萌发期耐盐性评价

应用隶属函数法,以发芽势,发芽率、根长、苗高、发芽指数、活力指数为指标,对紫花苜蓿(Medicago sativa)非秋眠型标准品种种子萌发期耐盐性进行评价.结果表明,50 mmol/L NaCl对紫花苜蓿种子萌发没有促进作用,而在NaCl浓度高于50 mmol/L下,紫花苜蓿发芽势、发芽率、根长、苗高、发芽指数、活力...     

口蹄疫病毒抗原决定簇融合基因转化苜蓿

摘要：通过农杆菌的介导,以携带O型和A型口蹄疫抗原决定簇融合基因O21 O14 A21 HBcAg的植物表达载体转化苜蓿(Medicago sativa)愈伤组织,并再生得到抗性植株。试验建立了苜蓿甘农1号愈伤组织再生系统;优化了农杆菌介导的苜蓿遗传转化系统;获得抗性再生植株4棵;GUS报告基因在转化的愈伤组织中得到瞬时表达;抗性植株PCR检测结果证实目的基因已经成功整合到苜蓿基因组中。     

16个紫花苜蓿品种在扬州地区生产性能与品质的比较

研究采用田间随机区组试验,比较了16个紫花苜蓿(Medicago sativa)品种在扬州地区的生产性能与品质,以期筛选出适合扬州地区气候条件的品种。结果表明,各材料间的生产性能差异较大,其中德宝平均生长速度最快,显著高于多叶王、苜蓿王、猎人河、盛世;爱菲尼特的干草产量最高,显著高于其他品种,其次为皋兰2号、三得利、多叶王;阿尔冈金的粗蛋白（CP）含量最高,但酸性洗涤纤维（ADF）、中性洗涤纤维（NDF）含量也较高,爱菲尼特CP含量仅次于阿尔冈金,但ADF、NDF含量显著低于阿尔冈金。综合评价,爱菲尼特的生产性能最好,其次为皋兰2号、三得利、多叶王,这几个半秋眠型品种较适于在扬州地区推广种植。