摘要:

SummarySorghum genotypes known to be resistant or susceptible to shoot fly,Atherigona soccataRondani were examined by scanning electron microscopy for differences in epicuticular wax structure and wetness of the central leaf whorl. Two major types of wax structures were observed: shoot fly resistant and moderately resistant genotypes were characterised by a smooth amorphous wax layer and sparse wax crystals while susceptible genotypes possessed a dense meshwork of crystalline epicuticular wax. The density of wax crystals decreased from the third leaf to the seventh leaf stage and was related to both seedling age and leaf position. Water droplets on susceptible genotypes with dense wax crystals showed spreading at the edges indicating a tendency to wet easily. In resistant genotypes with less dense wax crystals the droplets remained intact and did not spread.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04897.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryEggs, larvae, pupae and adults of the large narcissus fly (Merodon equestris) were reared at a series of constant temperatures between 9–24°C. Egg development required from 37 days at 9°C to 7 days at 21.5°C. The low‐temperature threshold for development was 6.7°C. Larvae reared at 1424°C were fully‐grown after 18 weeks, but it took much longer for such insects to pupate, and adult flies emerged only after about 45 weeks of development. Large narcissus flies enter diapause during the larval stage and overwinter as fully‐fed larvae, forming pupae in the following spring. Post‐winter pupation and pupal development took from 169 days at 10°C to 36 days at 21.5°C. Of this, pupal development required from 91 days at 10°C to 19 days at 21.5°C. The low‐temperature threshold for post‐winter pupation and pupal development was 7.1°C, and for pupal development alone, 7.2°C.Females maintained at or below 19°C laid few eggs, whereas some females kept at or above 21.5°C laid more than 100 eggs (mean 69 ± 36). Approximately 50% of females maintained at or above 21.5°C laid less than 10 eggs during their lifetime. The mean egg‐laying time was 6 to 9 days. Although temperatures at or below 19°C inhibited mating, once a female had mated, such temperatu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04898.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryLarge seed tubers (mean 134 g) and small seed tubers (50 g) of three early and three maincrop potato cultivars, spaced respectively 48 and 30 cm apart within rows, were inoculated withRhizoctonia solaniat planting in 1985 and 1986. All seed of early cultivars was sprouted and maincrop seed was either sprouted or not sprouted.In all cultivars, plant emergence was slower from small than large seed and with both was delayed by inoculation. From 11 wk after planting numbers of stems and tubers and weights of foliage and tubers/m2were usually similar from small and large seed when not inoculated, but inoculating delayed plant growth and decreased tuber numbers and yield more from small than large seed.Inoculating decreased mean yields from large and small seed of early cultivars at 11 wk by respectively 24% and 31% (Arran Comet), 12% and 18% (Estima) and by 10% and 28% (Wilja) and losses were greatest with saleable sized tubers (3–4 cm). When grown to maturity inoculating decreased yields by 7% (Arran Comet),5%(Estima) and 14% (Wilja).With maincrop cultivars, yields in October from large and small seed were decreased by respectively 4% and 10% (DCsirke), 9% and 12% (Maris Piper) and by 14% and 22% (Pentland Squire). In all cultivars yields of tubers82 mm were increased.The incidence of stem canker and of black scurf on progeny tubers was not affected by seed size but in all cultivars the percentage of greened tubers was slightly increased by inoculat

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04899.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryA hitherto undescribed virus, termed rottboellia yellow mottle virus (RoYMV), affectingRottboellia cochinchinensis(syn.R. exaltata, itch grass) at Ibadan, Nigeria, was investigated.RoYMV virions are isometric,c. 29 nm in diameter, and sediment homogeneously at 114s. In isopycnic CsCl gradients, RoYMV virions band sharply at a buoyant density of 1.379 g cm‐3, but in Cs2SO4gradients, virions band at two zones, at the densities of 1.300 g cm‐3and 1.325 g cm‐3. Treatment with EDTA at pH 8.0 reduced the sedimentation value of RoYMV to c. 87s and rendered it susceptible to proteinase‐K, SDS and NaCl. The apparent molecular weight of RoYMV coat protein wasc. 27 000. Virions encapsidate a single‐stranded RNA of mol. wt 1.4 × 106Da. BesidesR. cochinchinensis, RoYMV was mechanically transmissible only to maize (Zea mays). No reaction occurred when RoYMV was tested against antisera to 44 isometric plant viruses (belonging to 12 groups), including several that affect Gramineae.RoYMV exhibits striking similarities with other viruses belonging to the sobemovirus group, and it is tentatively designated as a new member of the sobemov

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04900.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryYoung almond (Prunus dulcis, cvs Carmel, Peerless and Price) orchards established on the plum rootstock Marianna 2624 (P. cerasifera×P. munsoniana) contained trees that exhibited poor terminal shoot growth and wilted, chlorotic leaves. The scion/rootstock graft union showed an external splitting of the bark and an internal line of necrotic bark tissues that extended into the woody cylinder of the union, which was deeply pitted. Affected trees declined. The disease was named almond brown line and decline (ABLD). Incidence of ABLD ranged up to 55% per cultivar in some orchards. Numerous attempts to graft‐transmit orchard collections of ABLD to healthy almond/Marianna 2624 indicators failed. Also, ABLD does not appear to be soil‐borne. However, ABLD was serendipitiously determined to be bud‐perpetuated when infected scion buds from an apparently healthy appearing Peerless almond/peach tree located in a foundation orchard were grafted onto healthy rooted cuttings of Marianna 2624 to produce yearling trees. Also, graft‐inoculations on the almond scion portion of healthy trees, but not the plum rootstock portion, with the peach yellow leafroll mycoplasma‐like organism (PYLR‐MLO) caused symptoms resembling ABLD. Laboratory and glasshouse assays of several symptomatic trees did not detect tomato ringspot virus and two ilarviruses. These results suggest that an MLO, possibly PYLR‐MLO, may be the causal agent of ABLD and that Marianna 2624 is probably resistant t

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04901.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryGeminiviruses associated with yellow or golden mosaic diseases of legume crops in two regions of India were compared by testing their reactivity with 27 monoclonal antibodies (MAbs) prepared to the particles of African cassava mosaic (ACMV) or Indian cassava mosaic (ICMV) viruses. The viruses fell into two main groups. Group 1 comprised isolates of dolichos yellow mosaic virus; these reacted with three or four ACMV MAbs and four ICMV MAbs. Group 2 comprised isolates of horsegram yellow mosaic virus, together with isolates from blackgram, cowpea, French bean, pigeonpea, soybean,Indigofera hirsutaand probably also isolates from mungbean. These reacted with three or four ACMV MAbs but with few or no ICMV MAbs. Isolates within each group differed slightly in epitope profile, depending on the source species (Group 2) or geographical origin (Groups 1 and 2). Isolates from lima bean resembled those in Group 2 but had some antigenic differences, and their status is uncertain. The poor detectability of geminivirus isolates in mungbean may reflect a low virus concentration in this species.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04902.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryDuring two surveys of beet root crops in South Kazakhstan and Central Asia conducted in 1988 and 1989, 465 of 990 samples were found to contain beet mosaic virus (BMV) by double‐antibody sandwich (DAS) ELISA. BMV infection was widely scattered in the area surveyed, and its incidence varied considerably, reaching 100% in some fields adjacent to beet seed crops. BMV isolates from Kazakhstan, Kirgizia, Uzbekistan and Ukraine were found to be serologically closely related in DAS‐ELISA test. Beet yellows virus (BYV) was not detected in any location surveyed in South Kazakhstan and Central Asia. BYV spread into the area is probably prevented by its geographical isolat

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04903.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryThe effect of co‐infection by maize streak virus (MSV) and maize stripe virus (MStV) on plant growth and grain yield was investigated in a susceptible variety of maize (Zea mays), ZS 5206, in Mauritius. Under natural conditions MSV, transmitted by the leafhopperCicadulina mbila, was normally established before MStV, which is vectored by the planthopperPeregrinus maidis;as a result, MStV symptoms were often partially or completely masked by those of MSV, making MStV detection by symptomatology very unreliable. MSV and MStV were diagnosed by ELISA and MStV by a novel method of detecting the MStV‐coded non‐capsid protein.The maize hybrid ZS 5206 was inoculated with either MSV, MStV or both, at two stages in the growth cycle (3–5 or 7–10 leaf stage). A greater reduction in plant growth was observed in plants inoculated singly with MStV (80% and 29% for first and second stage, respectively) than with MSV (50% and 23%, respectively). No cobs were produced by plants singly infected with MStV at the first stage, or co‐infected with MSV and MStV at both stages; however, marginal grain production was recorded in plants singly infected with MSV at the first stage (91% reduction), or infected either with MSV or MStV, at the second stage (65% and 80% reduction, respectively).In maize hybrid ZS 5206, MStV is more virulent than MSV; co‐infection by both viruses causes greater reductions in plant growth and grain yield than single infection by either virus at a given stage of plant development. In the event of co‐infection by MSV and MStV, yield losses can be erroneously attributed to MSV only if the symptoms of MStV are masked by those of the former and if adequate methods for MStV detecti

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04904.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryThe distribution of virus‐infected cells was examined, by fluorescence microscopy, within plants of a range of potato clones infected with potato leafroll luteovirus (PLRV). This range included nine PLRV‐resistant clones, of which four were transgenic lines carrying the PLRV coat protein gene and five were conventionally bred. Plants of these clones were resistant to PLRV multiplication and accumulated less virus antigen in leaf tissue than did susceptible clones. Indirect fluorescent antibody staining of thin sections from carbodiimide‐fixed petiole tissue revealed that in plants of PLRV‐susceptible clones, virus‐infected cells were abundant within both external (abaxial) and internal (adaxial) phloem bundles. In plants of the PLRV‐resistant conventionally bred clones and in resistant transgenic lines of cv. Pentland Squire, virus‐infected cells were much fewer in number and largely restricted to internal phloem bundles. In resistant transgenic lines of cv. Désirée, this restricted distribution of PLRV antigen was only detected in petioles of young leaves. The results suggest that the transgenic and a host‐mediated type of resistance that restricts virtis multiplication have underl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04905.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryA sap‐transmissible virus, provisionally named Sri Lankan passion fruit mottle virus (SLPFMV), was isolated fromPassiflora edulisf.flavicarpaand shown to induce leaf mottling and distortion in that host. The virus infected 23 species in five plant families with systemic infection being common in the Passifloraceae.Chenopodium amaranticolorwas a good local lesion host andPassiflora foetidawas a useful systemic host for purification. InP. foetidaextracts, SLPFMV lost infectivity after 10 min between 70–75°C, 6–7 days at 20–23°C and at dilutions of 10‐‐5‐W‐6. The virus had flexuous, filamentous particles with a normal length of c. 841 nm. Two polypeptides of mol. wt c. 33 200 and 28 700 were detected in purified virus preparations, and a major species of double‐stranded RNA (mol. wt 7.0 × 106), was detected in infected plants. Pinwheels, tubular and laminated inclusions were found in ultrathin sections of infectedP. edulisf.plavicurpaand cylindrical inclusions were observed in epidermal strips.SLPFMV was transmitted by the aphidsMyzus persicae, Aphis spiraecola, A. gossypüandA. cruccivoraafter brief acquisition feeds. SLPFMV reacted with antisera to several potyviruses including passion fruit woodiness virus, passion fruit ringspot virus, potato virus Y and watermelon mosaic virus 2 and thus, apparently, is a member o

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04906.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY