• Sydney Cross Harland

      Articles written in Journal of Genetics

    • The genetics of cotton. Part I. The inheritance of petal spot in New World cottons

      Sydney Cross Harland

      More Details Fulltext PDF
    • The genetics of cotton. Part II. The inheritance of pollen colour in New World cottons

      Sydney Cross Harland

      More Details Fulltext PDF
    • The genetics of cotton. Part III. The inheritance of corolla colour in New World cottons

      Sydney Cross Harland

      More Details Abstract Fulltext PDF

      Pale cream of Upland or Sea Island White, and yellow of grades 1 to 7, form an allelomorphic pair of characters which may be represented by the factor pairY-y.

      Segregation in inter-specific crosses is more complicated than in inter-Peruvian crosses, in that many intermediate grades of yellow are found inF2. In the inter-Peruvian cross involving Sea Island White there is sharp segregation inF2, with absence of intermediate grades.

      Upland and Sea Island White are both geneticallyy, but Sea Island White, having arisen directly from the yellow form by a single locus mutation, possesses a series of plus modifiers for yellow, while Upland possesses fewer modifiers. Segregation of modifiers produces the intermediate grades of yellow.

      The total number of modifiers is not known, nor has the attempt made to distinguish their specific effects been successful. Probably not less than 2 nor more than 7 modifiers are concerned.

      The occurrence of grades lighter or darker than the parents in theF2 of a cross between two yellows is considered to be due to new combinations of intensifiers.

      Some Uplands have intensifiers capable of raising Sea Island from grade 4 to grade 6, but there is no ease where Upland has intensified the colour of a Bourbon variety.

    • The genetics of cotton - Part IX. Further experiments on the inheritance of the crinkled dwarf mutant ofG. Barbadense L. in interspecific crosses and their bearing on the fisher theory of dominance

      Sydney Cross Harland

      More Details Abstract Fulltext PDF

      1. Further experiments are described on the mode of inheritance of the crinkled dwarf mutant ofG. barbadense Linn. when crossed with normalG. hirsutum Linn.

      2. Observations were made on the characters of crinkled when transferred by repeated back-crossing toG. hirsutum (T 9). Selfing of the heterozygotes of the fourth back-cross plants produced normal, intermediate crinkled, and extreme crinkled in a 1 : 2 : 1 ratio, and the results from selfing six back-cross heterozygotes showed that no change had taken place through further back-crossing.

      3. The new type ofhirsutum crinkled was apparently slightly less vigorous and productive than the originalbarbadense mutant, though under good conditions little difference was observable.

      4.Hirsutum heterozygous for the crinkled factor was shown to have a slight advantage over normal under good conditions and was not at any considerable disadvantage under bad conditions.

      5. Transference of crinkled to two further types ofhirsutum revealed complete or nearly complete dominance ofhirsutum to the crinkled type.

      6. The bearing of the experiments on Fisher’s theory of dominance is discussed and it is concluded that modification of the theory is necessary. Complete dominance of normal over crinkled exists in two types ofG. hirsutum although the crinkled mutant does not occur in that species. It is concluded that modifiers of dominance are of advantage to the wild type and are thus selected on their own account.

    • The genetics of cotton - Part XI. Further experiments on the inheritance of chlorophyll deficiency in new world cottons

      Sydney Cross Harland

      More Details Abstract Fulltext PDF

      1. Further experiments are described on the mode of inheritance and distribution in six species of New World cottons of a pair of duplicate factors for chlorophyll deficiency.

      2. Duplication of factors is considered to have taken place through polyploidy with subsequent mutation of one or other of the members constituting the pair in some of the species.Barbadense andDarwinii have become monomeric through the loss of factorChb whilepurpurascens, hirsutum, andtaitense, when monomeric, are shown to have lostCha.

      3. The experimental data support Haldane’s view that in polyploid species one member of a pair of duplicate genes may mutate without disadvantage, provided its functions can be performed by a gene in one of the other sets of chromosomes.

      4. The taxonomic and evolutionary significance of the results is discussed and it is suggested that the extent to which the dimeric condition is converted to the monomeric in polyploid species may provide some indication of the age of the species. In an old series of allopolyploids such as the New World species ofGossypium are considered to be, cases of dimery might be expected only infrequently, and usually only in interspecific crosses.

    • The genetics of cotton - Part XIII. A third series of experiments with the crinkled dwarf mutant ofG. barbadense L. the crossBarbadense crinkled ×Hirsutum crinkled

      Sydney Cross Harland

      More Details Abstract Fulltext PDF

      1. The cross betweenhirsutum crinkled (Type 9) andbarbadense crinkled gave inF2 a series of crinkleds ranging from an extreme and exaggerated type of crinkled (super-crinkled) to a type phenotypically indistinguishable from normal (pseudo-normal). In later generations several new types of crinkled were extracted in homozygous form.

      2. It is considered thatG. barbadense andG. hirsutum possess dissimilar modifier complexes, which in the interspecific cross are broken down, leading to the production of a varying series of genotypical backgrounds upon which the crinkled mutant manifests itself in a corresponding series of reactions, some favourably and others unfavourably.

      3. The conversion of the crinkled mutant to pseudo-normal by genic recombination resulting from the interaction ofbarbadense andhirsutum modifiers favours Fisher’s view that recessives may ultimately become merged in the wild type by accumulating modifiers.

      4. A new method for the production of duplicate genes is suggested.

    • The genetics of cotton - Part XIV. The inheritance of brown lint in new world cottons

      Sydney Cross Harland

      More Details Abstract Fulltext PDF

      1. The inter-barbadense cross Egyptian brown × Sea Island white gaveF1 intermediate and complicated segregation of the blending type inF2. This was demonstrated to be due to the fact that the factorKB of the brown parent was accompanied by a number of plus modifiers absent in the white parent.

      2. Repeated back-crossing of heterozygotes to the brown parent had the effect of equalising the plus modifiers of both the dominant and recessive phases of the factorKB. Selfing after three back-crosses gave simple segregation into 3 brown: 1 light brown.

      3. A negative correlation was shown to exist between lint colour and lint length, the factorKB or a factor closely linked to it conditioning a shortening in the lint length of approximately 5·1 mm. in the homozygous phase and 2·7 mm. in the heterozygous phase.

      4. Minor colour factors were also correlated with variations in lint length.

      5. The blending type of inheritance of brown lint in Egyptian × Sea Island is considered to be due to the disintegration by human agency of an original brown-lint factor complex.

      6. The cross of brownbarbadense × brownhirsutum was found to involve duplicate genes for lint colour. The distribution of the known pairs of duplicate genes inG. barbadense andG. hirsutum is discussed.

    • The genetics of cotton - XVII. Increased mutability of a gene inG. purpurascens as a consequence of hybridization withG. hirsutum

      Sydney Cross Harland

      More Details Abstract Fulltext PDF

      1. The geneSH (hirsutum petal spot) is slightly mutable somatically on (a) ahirsutum background, and (b) a background predominantlybarbadense.

      2. The geneSP (purpurascens petal spot) becomes increasingly mutable, both somatically and gametically,pari passu with the replacement ofpurpurascens byhirsutum genes.

      3. It is believed that species may possess modifier complexes, the effect of which is to preserve the stability of genes and prevent them from mutating at an excessive rate.Hirsutum andpurpurascens may be assumed to differ in the nature of such of their modifiers as affect the mutation rate ofSP.

      4. The genesSH andSP are members of the anthocyanin multiple allel series, and may be distinguished by the weaker manifestation ofSP in thehirsutum genotype.

      5. Other cases of mutability in interspecific hybrids are mentioned, and the possible significance to the plant breeder of mutability consequent on interspecific hybridization is referred to.

    • The genetics of cotton - XVIII. Transference of genes from diploid north American wild cottons (Gossypium thurberi, Tod.,G. armourianum kearney, andG. aridum comb.nov. skovsted) to tetraploid new world cottons (G. barbadense L. andG. hirsutum L.)

      Sydney Cross Harland Olga M. Atteck

      More Details Fulltext PDF
    • The genetics of cotton - XIX. Normal alleles of the crinkled mutant ofGossypium barbadense L. differing in dominance potency, and an experimental verification of fisher’s theory of dominance

      Sydney Cross Harland Olga M. Atteck

      More Details Abstract Fulltext PDF

      1. The dominance relations of the crinkled mutant ofGossypium barbadense L. have been studied in an extensive series of backcrossing experiments, involving six species of New World cottons.

      2. It is believed that there have been two methods by which dominance at the crinkled locus in the six species of New WorldGossypiums has been attained. The first method is that proposed by Fisher, whereby dominance has been reached by modification of the heterozygous phase (hirsutum, purpurascens, andTaitense). The modifiers improving the heterozygous phase have simultaneously improved the recessive. The second method is that proposed by Haldane, in which dominance is attained by the employment of a normal allele of great dominance potency (barbadense, tomentosum, andDarwinii), the recessive phase being relatively unmodified.

      3. Some conditions under which the Fisher effect is operative are discussed.

      4. Evidence is brought forward indicating that the normal allele ofbarbadense,CRB, may become mutable on the genetic background of one type ofpurpurascens.

  • Journal of Genetics | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.