甘蔗品种黑穗病抗性评价体系的建立

为了建立甘蔗品种黑穗病抗性评价体系,选用9个引进品种,设计一个包括6个对照品种在内的田间试验。首次采用混合小种进行人工浸渍接种,通过整个新植蔗生长季病害进展曲线下的面积、茎感染率和株感染率3个病情指数,以及病害流行学参数潜伏侵染期和持续发病期的分析,对其扰痛性进行评价。在分析以上参数相关程度的基础上,引进了系统聚类分析法进行进一步评价。结果显示;9个引进甘蔗品种中,ROC26属于感病品种,其余属于抗病或高抗品种;3个病情指数和持续发病期的两两相关均为显著正相关,潜伏侵染期与这些参数的相关为负相关,但未达到显著水平;在类间距离大于1．0的条件下,可将15个品种聚为6类,进一步明确了备品种抗黑穗痛性的相似程度;抗性鉴定标准对照种NC0310、F134、NC0376和Ya71—374的应用,明确了接种源为小种1和小种2,通过一次接种试验,明确了供试品种对2个小种的抗性水平,标准对照种的抗性表现,还说明了本生长季发病条件基本是适宜的。本文建立的甘蔗品种抗黑穗病评价体系是切实可行的。     

THE INCIDENCE OF CERTAIN SEED-BORNE DISEASES IN COMMERCIAL SEED SAMPLES: I. LOOSE SMUT OF BARLEY, USTILAGO NUDA (JENS.) ROSTR.

A simple whole-embryo test for detecting the presence of loose smut, Ustilago nuda , in barley grains has been developed and is described. Embryos from 1000 grains can be examined within 24 hr. and the actual working time per sample is just over 1 hr.
The results of embryo tests showed a high positive correlation with the incidence of the disease in field plots, ( r = 0.83).
Commercial samples of seed barley, submitted in 1954-57 to the Official Seed Testing Station, have been examined by this embryo test for the presence of loose smut. The varieties received could be clearly divided into two groups: the Scandinavian-bred varieties, e.g. Carlsberg and Herta, having 84% of the samples infected, with the level of infection up to 19%; and the English-bred varieties, e.g. Proctor and Plumage-Archer, where only 9.5% of the samples were infected, with the level of infection rarely more than 0.5%. In spite of differences in weather conditions during the period when infection occurred seasonal variations in the incidence of loose smut were not obvious from the results in the 3 years.     

Production of huitlacoche, Ustilago maydis: timing inoculation and controlling pollination

Huitlacoche is the name given to young, fleshy, edible galls that form when ears of Zea mays are infected by Ustilago maydis. Huitlacoche is processed and sold fresh at markets in Mexico. Interest has increased recently in producing U. maydis as a specialty mushroom in the United States. Silk-channel inoculation methods developed to evaluate common smut resistance in maize can be used to produce huitlacoche commercially. This research assessed the effects of time of inoculation and preventing pollination on the severity of ear galls and yield of huitlacoche produced by inoculating silks with U. maydis. Yield of huitlacoche and severity of ear galls were closely related, as was evident from highly significant linear or curvilinear regressions. Severity and yield were greatest when ears were inoculated 4-8 d after the mid-silk growth stage. Ear galls were 5-15% more severe and yield of huitlacoche was 18-150% greater on ears that were not pollinated, compared to those that were pollinated. Maximum yield of huitlacoche was 131 g ear(-1) from unpollinated male-sterile field corn inoculated 6 d after the mid-silk growth stage and 92 g ear(-1) from detasseled sweet corn inoculated 6 d after mid-silk. About 25% of the total weight of ears consisted of marketable huitlacoche when yields were highest. Quality of huitlacoche was not affected by time of inoculation or pollination treatments, but quality of huitlacoche harvested 12-14 d after inoculation was unacceptable primarily due to lack of teliospores, which affected color and flavor.     

THE REACTION OF WHEAT VARIETIES TO LOOSE SMUT AS DETERMINED BY EMBRYO, SEEDLING, AND ADULT PLANT TESTS

The possibility of using an embryo test as a means of determining the reaction of wheat varieties to loose smut ( Ustilago tritici (Pers.) Rostr.) has been investigated. Fifty-seven varieties were inoculated with two physiologic races by the partial vacuum method and the embryos, seedlings, and adult plants were examined for infection. Most of the varieties were fully susceptible to one or both races, and only ten showed real resistance to any one race. Braun R and Molinel proved almost immune to infection. The resistance in other varieties which showed no infection in the field was expressed as embryo susceptibility, i.e. the embryo became infected in much the same way as in field-susceptible varieties.
In the latter varieties infection passes from the embryo into the growing point of the young seedling. In the embryo-susceptible field-resistant varieties, infection does not pass from the scutellum and the growing point is therefore uninfected.
The reaction of most of the varieties tested was straightforward resistance or susceptibility, but in a few varieties a small proportion of the grains reacted differently from the majority. These reactions are discussed.     

高粱对丝黑穗病的抗性及遗传研究

1981—1985年在人工接种的条件下,对1239份高粱品种资源,进行了抗丝黑穗病性鉴定。与此同时,用17个抗性不同的品种系,按照不完全双列杂交设计,进行了高粱对丝黑穗病的抗性遗传研究。结果表明,高粱对丝黑穗病的抗性遗传方式因品种而异。有的品种系具数量性状遗传特点,有的则具有质量性状遗传特点。抗病性属数量性状遗传的品种系,其抗性主要是受加性基因控制。     

A COMPARATIVE ANALYSIS OF THE ECOLOGICAL SIGNIFICANCE OF MAXIMAL LOCOMOTOR PERFORMANCE IN CARIBBEAN ANOLIS LIZARDS

We examined the sprinting and jumping capabilities of eight West Indian Anolis species during three natural activities (escape from a predator, feeding, and undisturbed activity). We then compared these field data with maximal performance under optimal laboratory conditions to answer three questions: (1) Has maximal (i.e., laboratory) sprinting and jumping performance coevolved with field performance among species? (2) What proportion of their maximum capabilities do anoles sprint and jump in different ecological contexts? (3) Does a relationship exist between maximal sprinting and jumping ability and the proportion of maximal performance used in these contexts? Among species, maximal speed is tightly positively correlated with sprinting performance during both feeding and escape in the field. Sprinting speed during escape closely matches maximal sprinting ability (i.e., about 90% of maximum performance). By contrast, sprinting performance during undisturbed activity is markedly lower (about 32% of maximum) than maximal sprinting performance. Sprinting ability during feeding is intermediate (about 71% of maximum) between field escape and field undisturbed activity. In contrast to sprinting ability, jumping ability is always substantially less than maximum (about 40% of maximum during feeding and undisturbed activity). A negative relationship exists among species between maximal speed and the proportion to which species sprint to their maximal abilities during field escape.     

Comparison of Resistance to Cotton Leaf Curl Disease (Multan/Burewala) in Gossypium hirsutum L. Varieties and Breeding Lines

Twenty‐four cotton varieties and advance breeding lines were evaluated for their resistance to cotton leaf curl disease (CLCuD; Multan/Burewala) under natural field and in glasshouse conditions for two consecutive years. Resistance was based on symptom expression and disease severity index. All the cotton genotypes exposed to the vector whitefly in the field and artificially infected by grafting manifested a high level of resistance against CLCuD (Multan) with the exception of genotype NIAB‐999 that was moderately resistant. All the test varieties/breeding lines were highly susceptible to CLCuD (Burewala) both in the field and the glasshouse. However, substantial differences were noted between genotypes for disease index under field conditions. Graft inoculation studies showed that all genotypes inoculated with CLCuD (Burewala) developed disease within 9–13 days whereas those graft‐inoculated with CLCuD (Multan) developed symptoms from 15 to 22 days after grafting. Severe reduction occurred in plant morphology, fibre and yield parameters of cotton variety NIAB‐111 following inoculation with CLCuD (Burewala) as compared with CLCuD (Multan).     

TMV-Infection syndromes in potato cultivars Erika and Krasava

Tre potato cultivars Erika and Krasava are unable to reproduce two strains of TMV systemically except when in graft symbiosis under normal greenhouse conditions with tomato which has been infected with the virus. The escape resistance of potato to TMV infection due to slight hypersensitivity was not changed either by long-lasting non-infectious symbiosis with TMV-sensitive tomato or in a constant environment (32±2 °C, 9 700 lx) which was adequate to change the hypersensitive reaction of some other TMV-hosts. On the contrary, enhanced temperature provoked a still more severe local and necrotic response in the potato varieties. This led to systemic necrosis and the quick death of potato components systemically infected in graft symbiosis with tomato under normal greenhouse conditions when transferred into an environment of enhanced temperature.     

INVESTIGATIONS ON RESISTANCE TO DISEASE AMONG SPECIES OF THE GENUS AVENA

Fifty-three samples representing species of the genus Arena were tested for resistance to infection by Ustilago avenae and U. kolleri following artificial inoculation. Among the diploid and tetraploid species tested, eleven out of thirty-seven samples of Arena strigosa subsp. strigosa showed complete resistance to all the cultures with which they were inoculated. Avena strigosa subsp. barbata (three samples), and Avena strigosa subsp. abyssinica (one sample), also proved to be resistant to all the available races.
Variation in morphological and physiological characteristics within species and samples (varieties?) of the lower chromosome groups of Avena were observed and its consequences in breeding and race identification discussed.
Race identification was carried out on the eight Ustilago cultures and the existence of at least six races established. The tester varieties used in the present study proved inadequate for the complete separation of the smut races.     

THE LINE-PATTERN VIRUS DISEASE OF PLUMS

The disease, now usually called line-pattern of plum, has been described under many names in most countries where plums are grown extensively.
Naturally infected trees show widely differing Symptoms; this has two causes: (1) different varieties react differently to the same isolate of the virus, and (2) different isolates cause different symptoms in the same variety. Because the virus occurs in strains with different pathogenicities, the choice of indicator varieties is important when selecting virus-free material by transmission tests. Peach seedlings and the mazzard clone, F 12/1, were the most sensitive types found.
The line-pattern virus does not become fully systemic in some varieties of plum. In this and other respects, it resembles the viruses that cause apple mosaic; three isolates obtained from plum and two from apple produced similar Symptoms in peach and apple. It is therefore suggested that plum line-pattern and apple mosaic viruses are caused by strains of one virus.     

Evaluation of improved and local/landrace/sorghum varieties for covered kernel smut

Twelve varieties of improved and local (landrace) sorghum were tested under artificial inoculation conditions. Out of 12 sorghum varieties evaluated with covered kernel smut, notably local cultivar ‘Tetron’ was found to be highly resistant. Disease incidence and severity on the rest of the cultivars varied from 21 to 47% and 40 to 53% respectively. Differences among cultivars in yield loss were also observed. The highest yield loss (40%) was recorded on 97 MW 6129 (NVT-11 4) and for Tetron yield loss was nil. The effect of disease on germination was noticed but cannot be considered as conclusive due to moisture stress at the time of germination.     

SOME EFFECTS OF VIRUS INFECTION ON LEAF WATER CONTENTS OF NICOTIANA SPECIES

Infection with tobacco mosaic virus decreases the water content which detached tobacco leaves attain when kept for 20 hr. in conditions of minimum water stress, and does so more when the plants are kept in light before inoculation than when they are kept in darkness. No such effects of infection during the first day after inoculation were obtained with tobacco leaves infected with either tobacco etch virus or potato virus X , or with Nicotiana glutinosa leaves infected with tobacco mosaic virus. These results, like those showing early effects of TMV on respiration and photosynthesis of tobacco leaves, suggest that inoculation with TMV affects deeper leaf tissues than the epidermis earlier in tobacco leaves than in other leaves, and earlier than other viruses in tobacco leaves.     

A Comparison of Three Experimental Designs for the Field Assessment of Resistance to Rice Blast Disease (Pyricularia oryzae)

The reliability and the effectiveness of three field experimental designs for the assessment of varietal resistance to Pyricularia oryzae was studied for 2 years. Plants were arranged in the field using two sets of three designs: randomized compete block (RCB), adjacent control (AC) and honeycomb (HC). In the first set, plants were inoculated with the fungus and in the second one, plants were naturally infected. Four varieties were used, Maratelli (susceptible control), Roxani, Selenio and Senia (main varieties). Disease progress was recorded as leaf and neck blast. The number of plants of the main varieties required in each design was higher for RCB (90) and lower for AC and HC (30 and 32, respectively). Results showed that disease severity was significantly different in the varieties studied and it was consistent and not affected by the plant arrangement in the field. All experimental designs were reliable and effective for the assessment of leaf and neck blast under inoculation or natural infection. AC and HC designs had the advantage of requiring fewer plants over RCB one. This could be important in cases where seed availability is a limiting factor.     

Further studies on a British form of pea early-browning virus

An isolate of pea early-browning virus from Britain (PEBV (B)) has tubular particles most of which are either about 103 or 212 mμ long with sedimentation coefficients of 210 and 286 S respectively. Both types show cross-banding at intervals of 2.5 mμ. Virus preparations containing only the shorter particles were not infective. PEBV (B) was transmitted to pea seedlings by both adult and juvenile Trichodorus primitivus (de Man) (Nematoda) and persisted for 32 days in T. primitivus kept without plants. In two experiments T. primitivus failed to transmit a Dutch isolate (PEBV (D)), which is distantly related serologically to PEBV (B). PEBV (B) was transmitted by nematodes to cucumber roots more readily in soil at 20d? than at 24d? C., and more readily at 24d? than at 29d? C. When transmitted by inoculation of sap, PEBV (B) and PEBV (D) caused similar symptoms in some pea varieties but differed in virulence towards others. Thirty-one varieties resistant to natural infection with PEBV in The Netherlands were susceptible to PEBV (B) when manually inoculated with sap or when grown in naturally infested soil from one site; twenty-six of these varieties did not become infected in soil from a second site, in which several other varieties that are susceptible in The Netherlands were infected. Varieties should therefore be tested for resistance by growing them on many infested fields. All but one of the pea varieties resistant to PEBV in The Netherlands became infected with the English form of tomato black ring virus when grown in soil containing infective Longidorus attenuatus Hooper.     

Spore Liberation and Dispersal in Smut Fungi*

Teliospores are the most important diaspores of smut fungi, albeit not the only ones. The role of basidla, basidiospores, secondary spores, yeast cells, and infected parts of the host for dispersal has often been neglected. Many smut species have soral structures like galls, peridia, and elaters, which cause teliospores to be liberated over prolonged periods. This increases the chance that at least some spores are released under favourable wet climatic conditions and while host plants are susceptible. In this review, the diversity of dispersal units as well as vectors of smut fungi are presented. The importance of timing of diaspore liberation, flexibility in dispersal strategies, and the genetic and evolutionary implications of dispersal strategies of smut fungi are discussed. The general considerations are complemented by examples based on original field and laboratory observations: peridia of Farysia corniculata and certain species of Sporisorium expose the spore mass by hygroscopic movement under wet conditions (hygrochasy) favourable for teliospore germination and infection of a host plant. Basidia with firmly attached basidiospores liberated from spore balls of Doassansiopsis deformans, branched basidiospores of Rhamphospora nymphaeae, needle-shaped basidiospores of species of Entyloma, folded basidiospores of Mycosyrinx cissi, and stellate groups of yeast cells of Trichocintractia utriculicola show enlarged surfaces, which are advantageous for dispersal in water. Galls filled with spore balls of Doassansiopsis limnocharidis and witches' brooms formed by spikelets infected by Cintractia standleyana separate from the host and fall into water where they are dispersed.     

THE EFFECT OF DATE OF SOWING ON THE INCIDENCE OF POWDERY MILDEW ON SPRING-SOWN CEREALS

Delaying the date of sowing of spring-sown barley in 1953 and wheat in 1954 from February to April increased the incidence of powdery mildew, Erysiphe graminis DC., from May onwards. Before then, conditions did not favour the rapid spread of mildew.
From mid-June, infected barley produced necrotic lesions. These developed sooner on the early- than on the late-sown crops, and on the lower than upper leaves. Perithecia were first seen on 29 June. They were abundant on the wheat by 20 July.
Mildew reduced the yield of barley sown on 30 March and 28 April 1955 by 8 cwt./acre. The percentage loss was greater in the late- than in the early-sown crops. The number of ears per metre of row, the weight of 100 ears and the 1000-grain weights were reduced. Altering the seed rate from 1 ½ to 2½ bushels/acre did not affect the incidence, or the effect, of mildew on grain yield.     

Benzoxazinoid concentrations show correlation with Fusarium Head Blight resistance in Danish wheat varieties

Fusarium Head Blight (FHB) is a destructive disease that affects the grain yield and quality of cereals. The relationship between the natural defense chemicals benzoxazinoids and the FHB resistance of field grown winter wheat varieties was investigated. FHB resistance was assessed by the inoculation of wheat ears with mixtures of Fusarium avenaceum, Fusarium culmorum, Fusarium graminearum, and Microdochium nivale.     

Impact of aggressiveness of <Emphasis Type="Italic">Fusarium graminearum</Emphasis> and <Emphasis Type="Italic">F. culmorum</Emphasis> isolates on yield parameters and mycotoxin production in wheat

Plant-associated isolates from Fusarium graminearum and F. culmorum were inoculated on wheat in field experiments in 2007 and 2008 to ascertain their influence on fungal colonization of the ears, as well as mycotoxin contamination (deoxynivalenol, DON; nivalenol, NIV; zearalenone, ZEA) and yield parameters in the mature crop after inoculation with or without irrigation. The isolates were assigned to four different groups of aggressiveness on the basis of pathogenic symptom development and mycotoxin production in vitro. Increased levels of trichothecene-producing Fusarium DNA in the ears indicated a successful inoculation of the plants, which resulted in increased DON content in the wheat kernels in 2007. Dry conditions at anthesis markedly suppressed fungal colonization as well as mycotoxin accumulation. However, due to precipitation during the ripening period, yield and thousand-kernel weight were similar whether or not irrigation was applied at the time of inoculation. The level of aggressiveness among the isolates as determined in vitro was not reflected in the field experiment. The activity of the extracellular invertase in developing ears increased as a plant response to pathogen infection, especially when the plants were irrigated at the time of inoculation. In 2008, the Fusarium inoculation of wheat heads did not cause fungal growth and mycotoxin contamination in the grain, because of the dry weather conditions that occurred over the entire period of anthesis and ripening. The risk of future mycotoxin contamination in grains was discussed based on climate change prognosis.     

海南普通野生稻稻瘟病抗性资源调查和鉴定

为挖掘海南普通野生稻稻瘟病抗性资源,2010年诱发鉴定了41个居群410份材料苗期叶瘟,2011年接种稻瘟病菌（YC25）鉴定了37个居群121份材料穗颈瘟,2012年调查了80个居群2461份材料田间自然状态的抗病性。结果表明：苗期叶瘟抗性鉴定有21份高抗、117份抗病。苗期抗、高抗叶瘟性的138份材料中穗颈瘟鉴定4份高抗和3份抗病,14份表现为田间自然抗病。苗期叶瘟鉴定不抗病或未作此鉴定材料中,4份表现为抗穗颈瘟和田间自然抗病。这些抗性材料来自海口、文昌、万宁、三亚、澄迈、东方等地。本研究为海南普通野生稻资源进一步研究和抗稻瘟病育种利用提供参考