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  • Oxalis tuberosa  (2)
  • Schizaphis graminum
  • 1
    Electronic Resource
    Electronic Resource
    Expression of stylar incompatibility in the Andean clonal tuber crop oca (Oxalis tuberosa Mol., Oxalidaceae) (2000)
    Springer
    Sexual plant reproduction 13 (2000), S. 105-111 
    Details
    ISSN: 1432-2145
    Keywords: Key words Oca ; Oxalis tuberosa ; Floral heteromorphy ; Self-incompatibility ; Pollen fertility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Long-, mid-, and short-styled clonal accessions of oca (Oxalis tuberosa) were intercrossed in a complete diallelic design. Pollen tube growth in styles was monitored in all diallelic crosses. Pollen fertility was estimated by two tests: staining of pollen grains with aceto-carmine and detection of β-galactosidase activity by the substrate X-Gal. The two methods of pollen fertility estimation were equally useful to detect fertility levels. Pollen originating from short stamens had the highest fertility (85%) and pollen from long stamens had the lowest fertility (70%). Pollen fertility was high throughout, but its degree varied with the stylar morph on which the pollen was formed. Long-styled accessions had the highest rates of fertile pollen. Differences in pollen fertility at different anther levels in the same style morph were also apparent. Pollen grain diameter of the six morph-anther level combinations was inversely correlated with pollen fertility. Pollen grains from long stamens were the largest and pollen grains from short stamens were the smallest. Neither pollen fertility nor pollen grain size had an influence on pollen tube growth in the style or on fruit and seed set. Pollen tubes growing within the styles were inhibited at a different level for each of the 18 cross combinations in the diallel. Although legitimate crosses had greatest pollen tube growth, some of the illegitimate inter- and intramorph crosses had equally high scores. Of all illegitimate crosses, mid-styled seed parents had the lowest level of stylar incompatibility. Fruit and seed set were highly correlated with the extent of pollen tube growth in the style. The number of pollen tubes entering ovules in a flower was in good agreement with the number of seeds produced per fruit. Therefore, it is concluded that stylar incompatibility is the major determinant of limited seed formation in oca even in the most successful legitimate cross combinations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970000040
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  • 2
    Electronic Resource
    Electronic Resource
    Toxicity and feeding deterrency of hydroxamic acids from Gramineae in synthetic diets against the greenbug, Schizaphis graminum (1983)
    Springer
    Entomologia experimentalis et applicata 34 (1983), S. 134-138 
    Details
    ISSN: 1570-7458
    Keywords: Maize extract ; Hydroxamic acid ; Feeding deterrent ; Greenbug ; Schizaphis graminum ; Schizaphis graminum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La 2,4-dihydroxy-6-metoxy-1,4-benzoxazin-3-one (DIMBOA), acide hydroxamique le plus abondant dans des extraits de maïs, accroît la mortalité du puceron Schizaphis graminum nourri artificiellement. Des essais d'alimentation contrôlés par des moyens électriques démontrent que DIMBOA agit comme un répulsif, même à la concentration de 1 mM; dans des régimes à 12 mM, l'alimentation des pucerons est supprimée. Des expériences complémentaires indiquent diquent une augmentation de la mortalité des individus nourris avec DIMBOA par rapport aux témoins. Par conséquent, les effets nuisibles de DIMBOA sur les pucerons sont dus à sa répulsion. Le 2-\-0-gluco-side de DIMBOA (DIMBOA-Glc) a un effet important de répulsion sur les pucerons nourris artificiellement, mais affecte peu leur survie. L'importance des effets des DIMBOA et DIMBOA-Glc sur les pucerons par rapport à la resistance des céréales contre ces insectes est discutée.
    Notes: Abstract 2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), the main hydroxamic acid isolated from maize extracts, increased the mortality of Schizaphis graminum when fed in artificial diets. Electrically-monitored feeding assays showed that DIMBOA acted as a feeding deterrent at concentrations as low as 1 mM. On 12 mM DIMBOA diets, feeding by aphids was completely inhibited. Additional feeding experiments showed that when DIMBOA was ingested there was an increase in aphid mortality relative to that of aphids which did not ingest the compound. Thus, the deleterious effects of DIMBOA on aphids are due to feeding deterrency and toxicity. The 2-\-0 glucoside of DIMBOA (DIMBOA-Glc), the form in which DIMBOA naturally occurs in Gramineae, had a slight effect on lowering aphid survival and an appreciable feeding-deterrent effect on diet-fed aphids. The relevance of the effects of DIMBOA and DIMBOA-Gic on aphids to resistance of certain graminaceous crops against aphids is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338659
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  • 3
    Electronic Resource
    Electronic Resource
    Germplasm conservation of oca (Oxalis tuberosa Mol.) through botanical seed. Seed formation under a system of polymorphic incompatibility (1998)
    Springer
    Euphytica 101 (1998), S. 133-141 
    Details
    ISSN: 1573-5060
    Keywords: Oxalis tuberosa ; oca ; reproductive biology ; breeding system ; tristyly ; genetic resources
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seven clonal accessions representing all three stylar morphs of tristylous oca were intercrossed and selfed in a complete diallelic crossing design. The four traits total capsule production, total number of seeds/capsule, total number of seeds containing an embryo/capsule, and percent seeds containing an embryo of all seeds per capsule were recorded. Both capsule and seed production were highest in the legitimate pollinations (in which styles are pollinated with pollen of the corresponding anther level), but also in illegitimate pollinations of mid-styled seed parents with long-level anther pollen of short-styled accessions. All 18 types of pollination, consisting of 6 legitimate, 6 illegitimate intermorph, and 6 illegitimate intramorph pollinations, expressed gradually different levels of capsule and seed production. Intramorph pollinations and selfs of mid-styled seed parents were less incompatible than intramorph pollinations and selfs of the long- and short-styled morphs. All accessions studied expressed an intact system of heteromorphic stylar incompatibility despite their exclusive clonal propagation for millennia. A maximum of 16,3 seeds/capsule containing an embryo was obtained in an individual legitimate cross of two accessions, although an average of 25 ovules are present in a flower of O. tuberosa. The results are discussed in relation to the establishment of a genebank based on botanical seed of this clonally propagated, valuable Andean tuber crop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018336003573
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  • 4
    Electronic Resource
    Electronic Resource
    DIBOA in wild Poaceae: Sources of resistance to the Russian wheat aphid (Diuraphis noxia) and the greenbug (Schizaphis graminum) (1998)
    Springer
    Euphytica 102 (1998), S. 317-321 
    Details
    ISSN: 1573-5060
    Keywords: aphids ; cereal breeding ; DIBOA ; Diuraphis noxia ; hydroxamic acids ; pest resistance ; Poaceae ; Schizaphis graminum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Hydroxamic acids are secondary metabolites typical of Poaceae that play a role in cereal resistance against pests and pathogens. The content of the hydroxamic acid aglucones DIBOA (2,4-dihydroxy-1,4-benzoxazin-3-one) and DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) was evaluated in wild Poaceae belonging to the tribes Triticeae (genera Hordeum and Elymus) and Aveneae (genera Deschampsia and Phalaris). The concentration of DIBOA in seedling extracts of the wild barleys Hordeum chilense, H. brevisubulatum subsp. violaceum and H. bulbosum was negatively correlated with parameters related to performance of the cereal aphids Schizaphis graminum and Diuraphis noxia. The relevance of the results obtained for breeding programs aimed at increasing cereal resistance against aphids is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018323121213
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