Quorum-sensing signal production by Agrobacterium vitis strains and their tumor-inducing and tartrate-catabolic plasmids

Agrobacterium vitis strains, their tumor-inducing (pTi) and tartrate utilization (pTr) plasmid transconjugants and grapevine tumors were analyzed for the presence of N -acyl-homoserine lactones (AHLs). All wild-type A. vitis strains produced long-chain signals. PCR analysis of the A. vitis long-chain AHL synthase gene, avsI , showed the predicted amplicon. Agrobacterium tumefaciens UBAPF2 harboring various A. vitis pTi plasmids produced N -(3-oxo-octanoyl)- l -homoserine lactone encoded also by pTis of A. tumefaciens . UBAPF2 transconjugants carrying pTrs except for pTrTm4 and pTrAB3, also produced an AHL. UBAPF2 transconjugants carrying pTrAT6, pTrAB4 and pTrRr4 or pTiNi1 produced two additional AHLs not observed in the corresponding wild-type strains. We also provide evidence for in situ production of AHLs in grapevine crown gall tumors of greenhouse and field origin.     

T-DNA rearrangements due to tissue culture: somaclonal variation in crown gall tissues

After three years of apparent stability in tissue culture, the single cell derived shooty crown gall line sNT1.013 produced a revertant shoot which had switched from non-rooting (Rod⁺) and octopine synthesizing (Ocs⁺) to Rod^- Ocs^-, indicating that in this revertant TL-DNA genes 4 (causing the Rod⁺ trait) and gene 3 (causing the Ocs⁺ trait) had been inactivated. Southern blots revealed that the inactivation of these T-DNA genes was the result of a considerable rearrangement of DNA sequences, accompanied by deletions and possibly also by DNA amplifications. This study for the first time unambiguously proves that foreign genes which have been introduced via Agrobacterium tumefaciens can, at a low frequency, be inactivated after T-DNA integration because of reorganization of T-DNA sequences during tissue culture. This can be considered as an event of somaclonal variation.     

Complex segregation analysis of dental morphological variants

A set of 20 morphological variants of the dental crowns and four characteristics of the jaws are tested for probable mode of inheritance using the complex segregation analysis method of Morton et al. (Am. J. Hum. Genet. 23:602-611, 1971). Models tested include three two-allele single-locus models (dominant, codominant, and recessive) and a model employing the polychotomized normal distribution of liability (an additive polygenic model), with transmissibility estimated via maximum likelihood. Most of the traits studied are observed using ordinal scales with several grades, and many are tested using more than one dichotomy of their scale. These multiple analyses allow for an examination of such factors as trait incidence on the results of the statistical analysis. The results of the analysis yield propositions of major genes for 13 of the 24 traits examined. Two traits give good evidence of being polygenic in origin. The remaining nine characters present methodological problems that do not allow for a definite conclusion on their mode of inheritance at this time. The ability to test varying levels of transmissibility in the polygenic model allows for an estimation of the percentage of trait variance determined by familial factors. Estimates of transmissibility for all characters examined range from 0 to 1, with a mean of 0.36. These findings may suggest a large environmental role in the development of dental crown morphology. However, the possibility exists that difficulties in the ability to classify the expression of certain traits consistently result in overestimates of the environmental influences on the development of those characters.     

Identification of cytokinins in primary crown gall tumours of tomato

Abstract. Identification of the cytokinin complex of primary crown gall tumours of tomato ( Lycopersicon esculentum L.) by combined gas chromatography-mass spectrometry has been described. Several cytokinins have been identified which included zeatin, dihydrozeatin, isopentenyladenine, and their respective riboside and nucleotide derivatives. In addition, 6-benzylaminopurine, its riboside and the corresponding nucleotide have also been identified as major endogenous compounds in this tissue. This would appear to be the first report on the identification of cytokinins from a primary crown gall tumour tissue using unequivocal methods.     

Auxin-independent growth of maize tissue culture cells

Wall-regenerating protoplasts and suspension culture cells of Zea mays L. ‘Black Mexican Sweet’ were co-cultivated] with Ti plasmid-containing Agrobacterium tumefaciens strain ACH5. After elimination of the bacteria, putative transformants were selected for their ability to grow in the absence of added auxin. Althoug some of the treated cells grew, untreated controls and cells treated with the Ti plsmidless strain ACH5C3 also proliferated. The frequency of auxin-independent growth was similar in all treatments. Because none of 75 candidate transforms contained detectable T-DNA, the hormone-independent phenotype appears to be a consequence of habituation. Although some of the habituated colonies grew as undifferentiated callus, others produced rootlike structures. Miaze cells subcultured in liquid media containing progressively reduced concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) also became habituated.     

Assessment and monitoring of damage from insects in Australian eucalypt forests and commercial plantations

Abstract   This paper presents a review of recent developments in the assessment and monitoring of health in Australian eucalypt forests and plantations of pine and eucalypt species, with an emphasis on damage caused by herbivorous insects. The diverse range of interests and priorities amongst Australian stakeholders of native forests and plantations influences the scale, resolution and accuracy of results sought, and this in turn influences how the assessment data are collected, analysed and reported. The authors discuss sampling systems that include extensive ground-based surveys, permanent plots and airborne technologies being developed in Australia. In all cases, there is an appreciation that the assessment protocols should be objective, repeatable and cost effective. Significant progress has been made in the application of digital, remotely sensed imagery to detect and classify damaged forest canopies. The success of this approach depends, in part, on a sound understanding of the progression of symptoms at the leaf, tree crown and stand scale, especially those symptoms that influence spectral reflectance behaviour.     

Control of in vivo protein synthesis and peroxidase formation by DNA-containing extracts of normal and crown gall tissues

Nucleic acids extracted from normal bean hypocotyl tissue (NE) and crown gall tumors (TE) affect amino acid incorporation into protein and the development of peroxidase activity when vacuum infiltrated into normal receptor tissues. TE enhances and NE inhibits both processes; NE from successively older tissues produces progressively greater inhibitions per unit of infiltrated nucleic acid. The active material has an absorption maximum at 257 nm with an A_260:280 ratio of more than 2·0. On acrylamide gel electrophoresis it shows a small DNA peak, four typical r-RNA peaks and a small low molecular weight RNA peak. Activity in such extracts is completely destroyed by hydrolysis with 0·3 N KOH or DNAase; RNAase is only slightly effective and pronase ineffective. It is deduced that the effective material contains DNA that may be complexed with RNA or other materials in the extract. Pretreatment of donor tissues with actinomycin d or 5-fluorouracil diminishes or annuls the activity of the extract. Pretreatment of receptor tissue with actinomycin d inhibits the action of TE but not of NE; pretreatment with cycloheximide prevents the action of both NE and TE.     

Enamel hypoplasias as indicators of developmental stress in pongids and hominids

This paper reports the results from a study of enamel hypoplasia in the deciduous dentition of free-living Liberian chimpanzees (Pan troglodytes verus). The entire study collection includes 280 specimens (278 skulls plus two unassociated mandibles), of which 70 are young enough to retain some decidous teeth. Among the subsample of infants, the total frequency of hypoplasia summed over all teeth in any individual reaches 80%, being expressed in the form of pits rather than transverse lines. Hypoplasia of a linear form was common in the permanent dentition, attaining a frequency of 46.7% on maxillary central incisors and 69.7% on mandibular canines.