Mass-spectrometric quantitation of cytokinins in tobacco crown-gall tumours induced by mutated octopine Ti plasmids of Agrobacterium tumefaciens

The levels of the major cytokinins, zeatin, zeatin riboside, zeatin riboside-5-monophosphate and zeatin-7-glucoside were measured in tobacco (Nicotiana tabacum L.) crown-gall tissues carrying insertion and deletion mutations in the T-DNA. Measurements were made by combined gas chromatography-mass spectrometry using selected ion monitoring with ¹⁵N- and ²H-labelled internal standards. The results demonstrate that, relative to wild-type tumour tissue, cytokinin levels are considerably elevated in tissues lacking functional T-DNA auxin-biosynthetic genes. From a detailed analysis of the major cytokinin metabolites it is concluded that a reduction in the extent of cytokinin degradation via N⁶-side-chain cleavage is an important factor leading to increased cytokinin levels in these tissues.Abbreviations IAA indole-3-acetic acid - SIM selected ion monitoring - Z zeatin - [7G]Z zeatin-7-glucoside - [9R]Z zeatin-9-riboside - [9R-5P]Z zeatin riboside-5-monophosphate     

Histochemical observations on the crown skin of male baya: Lipids,lipase and phosphomonoesterases

Histochemical studies on localisation of lipids, lipase and phosphomonoeste-rases in the crown skin of male baya during non-breeding and breeding seasons were carried out. The results indicated a high turnover rate for lipid synthesis and its utilisation, increased acid and alkaline phosphatase activities in the crown skin of breeding male baya as compared to that in non-breeding season. It is surmised that crown skin of male baya becomes metabolically hyperactive during breeding season aiding processes such as cell growth and proliferation, keratinization and production of coloured feathers related to breeding.     

Plant tumor reversal associated with the loss of foreign DNA

Summary Transformation of plant tissues into crown gall tumors has been associated with the transfer of a portion of a tumor-inducing plasmid (Ti-plasmid) into plant DNA. Various laboratories have regenerated normal-appearing plants from a number of crown gall tumors. This study investigates the fate of the foreign DNA in a series of tissues derived from various parts of a plant regenerated from the tumor BT-37 by Braun and his coworkers. It was found that all the foreign DNA sequences were lost from tissues that had lost all their tumorous traits; whereas the plasmid DNA sequences were still present in tissues that appeared normal but still exhibited tumorous traits when returned to tissue culture media. From these studies it would appear that the presence of the Ti-plasmid sequences in the plant DNA is required for the maintenance of the transformed state. Presented in the Symposium on Gene Transfer, Differentiation and Neoplasia in Plant and Animal Cells at the 30th Annual Meeting of the Tissue Culture Association, Seattle, Washington, June 10–14, 1979. This symposium was supported in part by Grant CA 26748 from the National Cancer Institute, DHEW, and Grant RD-67 from the American Cancer Society.     

Responses of crown development to canopy openings by saplings of eight tropical submontane forest tree species in Indonesia: a comparison with cool-temperate trees

BACKGROUND AND AIMS: Growth in trunk height in canopy openings is important for saplings. How saplings increase height growth in canopy openings may relate to crown architectural constraints. Responses of crown development to canopy openings in relation to trunk height growth were studied for saplings (0.2-2.5 m tall) of eight tropical submontane forest tree species in Indonesia. The results of this study were also compared with those of temperate trees in northern Japan. METHODS: The crown architecture differed among the eight tropical species, i.e. they had sparsely to highly developed branching structures. Crown allometry was compared among the eight species in each canopy condition (closed canopy or canopy openings), and between closed canopy and canopy openings within a species. A general linear regression model was used to analyse how each species increases height growth rate in canopy openings. Crown allometry and its plasticity were compared between tropical and temperate trees by a nested analysis of covariance. KEY RESULTS: Tropical submontane trees had responses similar to cool-temperate trees, showing an increase in height in canopy openings, i.e. taller saplings of sparsely branched species increase height growth rates by increasing the sapling leaf area. Cool-temperate trees have a wider crown projection area and a smaller leaf area per crown projection area to avoid self-shading within a crown compared with tropical submontane trees. Plasticity of the crown projection area is greater in cool-temperate trees than in tropical submontane trees, probably because of the difference in leaf longevity. CONCLUSIONS: This study concluded that interspecific variation in the responses of crown development to canopy openings in regard to increasing height related to the species' branching structure, and that different life-forms, such as evergreen and deciduous trees, had different crown allometry and plasticity.     

Prosthetic crowns and other clinical risk indicators of caries among old-old Swedish adults: findings from the KEOHS Project. Kungsholmen Elders Oral Health Study

Objectives: The Kungsholmen Elders Oral Health Study (KEOHS) evaluated the oral health status of generally healthy, community‐dwelling persons over the age of 80 living in Kungsholmen, Sweden. This paper explored possible clinical risk indicators of coronal and root caries among the KEOHS subjects. Design: In this cross‐sectional study, dentate KEOHS subjects received a caries assessment using defined visual, tactile criteria. Setting: Examinations were carried out in two local clinics by standardized examiners. Subjects: One hundred twenty‐nine dentate persons were examined. Main Outcome Measures: The examination identified decayed and filled surfaces, prosthetic crowns, and missing teeth. Results: More root than coronal surfaces had untreated decay, and secondary root caries contributed the greatest number of decayed surfaces. Ninety percent of the examined dentate subjects had at least one prosthetic crown. Root surfaces exposed to crown margins were more likely to have caries than root surfaces not so exposed, particularly among women. The presence of untreated coronal caries (yes/no) was positively associated with having untreated root caries and an intermediate number (14–20) of teeth, but inversely associated with having 4+ prosthetic crowns. Active root caries (yes/no) was positively associated with having untreated coronal caries, 14–20 teeth, and 4+ prosthetic crowns. Nearly 20% of identified root lesions were present at or below the gingival margin, and most (88%) were secondary caries associated with crown margins (65%) or other restorations (23%). Conclusions: Our findings suggest that some dental characteristics, including the presence of prosthetic crowns, are risk indicators for the presence of untreated coronal and root caries.     

药用植物红芽大戟的个体生态学研究

报道了式芽大戟生长地的气候与植被状况,土壤条件以及它的生长动态。还研究了红芽大戟的越冬与繁殖。结果表明：红芽大戟是一种主要生长和分布在热带及南亚热带的药用植物。在广东它的生长动态呈双峰曲线,生长地土壤为砖红壤和红壤,砂茂越冬和根颈繁殖是引种驯化和生产上值得应用的方法。     

Genotypic variation in zinc efficiency and resistance to crown rot disease (Fusarium graminearum Schw. Group 1) in wheat

A crown rot disease in wheat caused by the fungusFusarium graminearum Schw. Group 1 is a widespread problem in chronically Zn-deficient Australian soils. A link between crown rot and Zn deficiency was established by Sparrow and Graham (1988). This paper reports a test of a further hypothesis, that wheat genotypes more efficient at extracting zinc from low-zinc soils are more resistant to infection by this pathogen. Three wheat cultivars (Excalibur, Songlen and Durati) of differential Zn efficiency were tested at three zinc levels (0.05, 0.5 and 2.0 mg Zn kg⁻¹ of soil) and three levels ofF. graminearum S. Group 1 inoculum (0.1 g and 0.3 g kg⁻¹ live chaff-inoculum and control having 0.1 g kg⁻¹ dead chaff inoculum). Six weeks after sowing dry matter production of shoots and roots was decreased byFusarium inoculation at 0.05 mg and 0.5 mg kg⁻¹ applied Zn.Fusarium inoculum at 0.1 g was as effective as 0.3 g kg⁻¹ for infection and decreasing dry matter. The infection at the basal part of culm decreased significantly by increasing the rate of Zn application. Excalibur, a Zn-efficient cultivar (tolerant to Zn deficiency) produced significantly more shoot and root dry matter, and showed less disease infection compared with Zn-inefficient cultivars (Durati and Songlen) at low (0.05 mg Zn kg⁻¹ soil) and medium (0.5 mg Zn kg⁻¹ soil) Zn fertilization rates. Higher rate of Zn fertilization (2.0 mg Zn kg⁻¹ soil) reduced the disease level in Durati to the level of Excalibur but the disease level of Songlen was still high, indicating its high Zn requirement and or sensitivity to crown rot. The data on Zn uptake show that Excalibur, being Zn-efficient, was able to scavenge enough Zn from Zn-deficient soil, we suggest that besides sustaining growth Excalibur was able to build and maintain resistance to the pathogen; inefficient cultivars needed extra Zn fertilization to achieve performance comparable to that of Excalibur. The present study indicates that growing Zn-efficient cultivars of wheat along with judicious use of Zn fertilizer in Zn-deficient areas where crown rot is a problem may sustain wheat production by reducing the severity of the disease as well as by increasing the plant vigour through improved Zn nutrition. ei]Section editor: R Rodriques-Kalana     

The relationship between colonisation and crown rot symptoms in strawberry plants infected with Phytophthora cactorum

Strawberry tissues infected with Phytophthora cactorum were comminuted and plated in a selective antibiotic agar medium to determine levels of tissue colonisation as indicated by the number of colony forming units (CFU) recovered per gramme of infected tissue. The number of CFU recovered per gramme of tissue increased logarithmically with the amount of necrosis in infected crown, leaf and petiole tissues. Under the conditions of enhanced susceptibility to infection and colonisation caused by cold storage treatments, this relationship between colonisation and necrosis was not significantly altered in the susceptible cv. Tamella. A recovery index was used to determine the effect of infected tissues on the recovery of CFU. This indicated that increasing levels of host colonisation stimulated CFU recovery and may partly explain the large increase in CFU g^-1 with larger amounts of necrosis. The amount of tissue colonisation was greater in inoculated plants of the susceptible cv. Tamella than in less susceptible cv. Cambridge Favourite, although the necrotic tissues of the latter contained more CFU g^-1, indicating a greater level of tolerance to colonisation. In cv. Tamella small amounts of colonisation were capable of causing wilt symptoms, although no wilted plants contained less than 200 CFU g^-1. Conversely, plants containing more than 1000 CFU g^-1 always wilted. In the early stages of infection, low levels of colonisation could be detected in strawberry crowns in the absence of symptoms. Dormant strawberry plants of cv. Tamella were readily infected by P. cactorum zoospore inoculations but, unlike actively growing plants, the majority of infections remained latent. These latent infections exhibited little or no symptoms and CFU recoveries from infected tissues were always below 100 CFU g^-1.