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  • 1
    ISSN: 1871-4528
    Keywords: gene expression ; cDNA-AFLP ; RNA-fingerprinting ; organogenesis ; tuberisation ; dormancy ; sprouting ; cluster analysis ; metabolic pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato tuber life-cycle is composed of many individual developmental stages including tuber formation, tuber development, dormancy and sprouting. We have used cDNA-AFLP fingerprinting to analyse gene expression in 24 individual stages of development, over the period from stolon formation through sprouting. In addition to these developmental stages, different tissues were analysed to assess tissue specificity and various controls were incorporated to determine process specificity. In total around 18000 transcript derived cDNA fragments (TDFs) were visualised from which circa 2600 were included in a statistical analysis allowing general conclusions about gene expression during development. More than 200 process specific TDFs were isolated and sequenced throughout the potato tuber life-cycle. The sequence similarities of these TDFs to known genes give an insight into the kinds of processes occurring during tuberisation, dormancy and sprouting.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-9788
    Keywords: Alstroemeria ; bar ; GUS ; luciferase ; ubiquitin promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transgenic plants were obtained after particle bombardment of embryogenic callus derived from stem segments of two tetraploid Alstroemeria genotypes with plasmids containing different selection/reporter genes. Firstly, a plasmid containing a firefly luciferase reporter gene driven by the maize ubiquitin promoter (Ubi1), was bombarded into both friable embryogenic callus and proembryos. Transient and stable expression of luciferase was visually detected by a luminometer. This selection method is non-destructive and can be applied over the whole developmental process from callus to embryo and plantlet. Molecular proof of transformation was obtained both by PCR analysis and Southern hybridization. Secondly, a plasmid containing the bar gene together with an uidA gene coding for β-glucuronidase both driven by the Ubi1 promoter was bombarded into proembryos. The transgenic callus was effectively selected from the callus clumps four months after bombardment on a medium containing 5 mg/l phosphinotricin (PPT). Selection by PPT was efficient and labour-saving. Stable expression of GUS was confirmed by the histochemical staining assay and molecular proof was obtained by PCR analysis.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5060
    Keywords: Allium cepa ; bio-assay ; partial resistance ; Spodoptera exigua ; wild species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The beet armyworm (Spodoptera exigua Hübner)is the most important pest in tropical Alliumcultivations. All shallot (Allium cepa L. group Aggregatum) cultivars are susceptible to this pest. Therefore accessions from three wild Alliumspecies, namely A. galanthum Kar. et Kir., A. fistulosum L. and A. royleiStearn, next to A. cepa L. were used to screen for resistance. First of all, a reliable bio-assay had to be developed. To this end transparent plastic cages with in total 5 plants of one accession per cage were placed on per lite in a heated greenhouse. Five 3-day old larvae were inoculated on each plant. Eight days after inoculation the number of surviving larvae per cage and the mean fresh weightper larva was determined. The lowest larval survival (36%) was found on A. roylei. This was not, however, significantly different from other Allium accessions. Significant differences were found in the fresh weight per larva fed on different Allium accessions. The larvae survived on A. roylei had a very low fresh weight (10.3 mg per larva), while those on an accession of A. fistulosum had the highest fresh weight (45.1 mg per larva). The larval fresh weight on A. roylei was lower than all the other accessions except from the tropical shallot cultivar Bawang Bali. To check whether or not a toxic compound was involved in the resistance present in A. roylei, tenaccessions from four Allium species were screened. Five 3-day old larvae were inoculated on regularly replaced leaf material of each accession ofAllium species. No significant differences were found in mean fresh weight per larva and mean survival of larvae among different accessions. There were also no significant differences in pupal weight and developmental time. All larvae became pupae 10 days after inoculation. The data indicate that there is no toxic compound present in A. roylei. These results are underlined by the observation in the greenhouse bio-assay that A. roylei plants were equally damaged by the beet armyworm compared to otherAllium species. The results obtained so far therefore suggest that introduction of resistance to S. exigua via the exploitation of variation for resistance to the beet armyworm in A. roylei is unclear and that genetic engineering using Cry sequences could provide a way forward.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5060
    Keywords: self-incompatibility ; self-compatibility ; unilateralincompatibility ; pollen ; style ; Soianum verrucosum ; S.tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Diploid Solanum tuberosum (tbr), 2n=2x=24,can be crossed with S. verrucosum (ver) only when the latter is used as a pistillate parent but not reciprocally. This conforms to the phenomenon of unilateral incompatibility (UI) where a self-compatible species, like ver (SC) cannot be used as a male parent to cross with a self-incompatible (SI) parent like tbr. Even if ver × tbr hybrids are made, the F1 hybrids possess cytoplasmic male sterility and thus hinder genetic analysis of crossing barriers. Exceptionally, however, some diploid genotypes of tbr (SI) can be used as pistillate parents to cross with ver, and such exceptional tbr clones are called `acceptors'. Repeated backcrossing of acceptors to ver have resulted in male fertile genotypes that possess tbr cytoplasm and ver nucleus. These genotypes were used for the genetic analysis of `acceptance' and UI in thse experiments. It was found that acceptance of ver-pollen by tbr-pistils is based on a dominant gene A that expresses only in the absence of an inhibitor I. In the F1 hybrids, only the S-allele of tbr was expressedbut not that of ver. Concomitant with this observation, it was shown that ver does not produce style-specific S-glycoproteins that are responsible for self-incompatible reaction in diploid potato. Although the the F1 populations were SC, they segregated into SC and SI genotypes giving skewed segregation ratios for this trait. Because of this as well as the disappearance and re-appearance of SC trait in the offspring generations, it was necessary to postulate a more complex interaction between A and I. Models are presented in order to explain acceptance, non-acceptance and the expression of UI. It is concluded that at least four different loci are involved in the expression of UI.
    Type of Medium: Electronic Resource
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