A preliminary note on the Genetics of Fragaria

Ohne Zusammenfassung

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A preliminary note on the Genetics of Fragaria

     

遗传学双语教学探讨

遗传学双语教学是一个全新的教学研究领域。介绍了几种国外英语原版遗传学教材和教学参考书,并对遗传学双语教学方法进行了探讨。 Abstract:Bilingual teaching of genetics is a new teaching research area.This papper introduces a number of texts of genetics in English,and outlines principles of bilingual teaching of genetics.     

Studies of Growth and Development in the Genus Fragaria: V. Spring Growth

From observations of leaf emergence dates and periodical dissectionsof stem apices it appears that leaf initiation does not keeppace with leaf emergence during the spring. This leads to asubnormal number of enclosed leaf initials at each stem apexat some time in April or May. Forced plants behave similarly,and it is concluded from these results and from direct experimentsthat part of the lag of leaf initiation on leaf emergence isconnected in some way with the flowering of the first inflorescenceto emerge from the crown. Conditions in the bud at the end ofthe winter also lead to an excess of leaf emergence over leafinitiation in the early spring.     

Studies of Growth and Development in the Genus Fragaria: IV. Winter Growth

The initiation and growth of leaf primordia has been followedduring four winters, and similar rates were obtained in eachseason. When allowance is made for temperature differences,these rates are at a much lower level than during the activegrowing season. In this respect winter dormancy involves a physiologicalchange resulting in a lower level of activity rather than acomplete cessation of activity. Leaf emergence and expansion,on the other hand, is completely stopped during the winter;this appears to be the result of photoperiodic induction bythe shortening days of August and September and is not primarilydependent on the fall in temperature.     

Studies of Growth and Development in the Genus Fragaria: III. The Growth of Leaves and Shoot

Changes in leaf size and in the number and size of the leafcells have been followed throughout the growing season and duringdrought and defoliation. The duration of the meristematic phaseof primordium growth is the major factor affecting leaf sizein all cases, and a hypothesis is developed to account for thechanges. A new index of shoot growth reflecting the rate ofcell production is used, together with the leaf initiation rate,to distinguish changes in growth rate at the time of runnerproduction and inflorescence initiation.     

Proanthocyanidins from the roots of Fragaria vesca

Water-soluble proanthocyanidins obtained by fermentation of a tannin extract from Fragaria vesca were shown, mainly by ¹³C NMR and HPLC, to consist of procyanidins B₁, B₂ and B₅ together with catechins.     

Studies on the Genetics of Feeding Behaviour in the Cave Fish Astyanax mexicanus f. anoptichthys

The Mexican characid Astyanax mexicanus gave rise to a series of cavcrnicolous populations (“Anoptichthys”) not earlier than during the Pleistocene age. When searching for food the blind cave fish swims at an angle of about 45° to the ground. The river fish, however, when having no visual information, stands vertically on its head. With the aid of infrarcd-videorecording and on the basis of crossing experiments it could be demonstrated that this difference in feeding behaviour is controlled by polygenes, although frequency distributions of the crossings suggest an apparent monofactorial inheritance. The evolutionary processes of adaptive reduction of headstanding and of progressive development of the gustatory equipment are genetically independent and both traits have been achieved by small genetic steps.     

Polyploid inter-specific hybrids in the genus Fragaria

Conclusion In conclusion we think it necessary to lay stress on the great faculty to form diploid gametes, and in result polyploid forms shown by allFragaria species, as has been noted by the majority of investigators having worked with these plants.In result of our investigations of diploid-hexaploid and octoploid-hexaploid hybrids, we have found 16 cases of doubling of the chromosome number in sexual cells of hybrids, and 5 cases of doubling in pure species. A cytological analysis of all F₂ hybrids at our disposal (the number of chromosomes has been counted in 14 plants out of 25), as well as of back crosses (the number of chromosomes has been counted in 2 plants out of 6), will doubtless considerably increase this number. The differences in the chromosome sets (7 chromosomes being a whole set) of the species used in crossing, evidently, greatly promotes the above mentioned phenomenon.Starting from experimental data, there may be two ways of explaining the origin of the polyploid series ofFragaria, with 14, 28, 42, 56 somatic chromosomes, found under natural conditions. The first way is that of hybridisation, as a source of origin of polyploid species, (with different chromosome sets) with subsequent doubling of the chromosome number, giving rise to allopolyploids. In regards to the second way, cross pollination is but an external stimulating influence, similar to a series of other factors disturbing the normal course of reduction division, and giving rise to autopolyploids (analogous to the origin of our tetraploid). It is evident, that high polyploid species of the strawberry have originated in the first way.With 1 plate     

籼型三系杂交水稻地上部干物质重的发育遗传研究

采用数量性状的加性--显性发育遗传模型分析了按NCⅡ交配设计的两套籼型三系杂交水稻地上部干物质重的发育遗传规律．结果表明,在不同发育阶段,地上部干物质重以显性效应为主,控制地上部干物质重的加性效应基因几乎不表达,而显性效应基因在两年中的表达呈连续性,且在生长中期活动强度最大,环境和基因型互作会影响地上部干物质重加性效应基因的表达,而对显性效应基因表达的影响不明显,随着发育进程的推进,地上部干物质重杂种优势趋于减弱。     

Studies on Developmental Genetics at the 3rd Congress of All-Russian Society of Geneticists and Selectionists

Russian Journal of Developmental Biology -