Inheritance of petal colour and its independent segregation from seed colour in Brassica rapa

The inheritance of petal (flower) colour and seed colour in Brassica rapa was investigated using two creamy‐white flowered, yellow‐seeded yellow sarson (an ecotype from Indian subcontinent) lines, two yellow‐flowered, partially yellow‐seeded Canadian cultivars and one yellow‐flowered, brown‐seeded rapid cycling accession, and their F₁, F₂, F₃ and backcross populations. A joint segregation of these two characters was examined in the F₂ population. Petal colour was found to be under monogenic control, where the yellow petal colour gene is dominant over the creamy‐white petal colour gene. The seed colour was found to be under digenic control and the yellow seed colour (due to a transparent coat) genes of yellow sarson are recessive to the brown/partially yellow seed colour genes of the Canadian B. rapa cvs.‘Candle’ and ‘Tobin’. The genes governing the petal colour and seed colour are inherited independently. A distorted segregation for petal colour was found in the backcross populations of yellow sarson × F₁ crosses, but not in the reciprocal backcrosses, i.e. F₁× yellow sarson. The possible reason is discussed in the light of genetic diversity of the parental genotypes.     

Genetics of colour traits in common vetch (Vicia sativa L.)

Five parents of common vetch (Vicia sativa L.) having orange/beige cotyledon colour, brown/white testa colour, purple/green seedling colour and purple/white flower colour were crossed as a full diallele set. The inheritance patterns of cotyledon, testa or seed coat colour, flower and seedling colour, were studied by analyzing their F₁, F₂, BC₁ and BC₂ generations. The segregation pattern in F₂, BC₁ and BC₂, showed that cotyledon colour was governed by a single gene with incomplete dominance and it is proposed that cotyledon colour is controlled by two allelic genes, which have been designated Ct₁ and Ct₂. Testa colour was governed by a single gene with the brown allele dominant and the recessive allele white. This gene has been given the symbol H. Two complementary genes governed both flower and seedling colours. These flower and seedling colour genes are pleiotropic and the two genes have been given the symbols S and F.     

The inheritance of flower doubleness and nectary spur in Pelargonium x hortorum Bailey

Summary The formation of single flowers of 5 petals and 5 sepals is determined by the homozygous recessive state, dd, of the doubleness gene, D/d, which is epistatic to modifying genes determining flower type. In the presence of the dominant allele, i.e. genotypes DD or Dd, the flowers are semi-double or double. Owing to the D allele alone, the single frequency of 5 petals and 5 sepals is doubled to 10 petals and 10 sepals, of which up to 5 are petaloid, to give a semi-double flower. In addition, in the presence of the D allele, three modifying loci M1/m1, M2/m2, and M3/m3 are activated to give a series of distinct doubles with integral multiples of the basic perianth number. The homozygous recessive genes m1m1 and m2m2 both add an increment of 10 perianth parts, and m3m3 adds an increment of 20 perianth parts. In heterozygotes, M1m1, M2m2 and M3m3, the dominant alleles inhibit the incremental effect of their corresponding recessive alleles. The single flower cultivars investigated probably have the genotype dd, M1M1, M2M2, M3M3 and the semi-double cultivars the genotype Dd, M1m1, M2M2, M3M3.The single flowers have a nectariferous spur, characteristic of the genus, adnate to the pedicel. As the spur is absent from semi-double and double flowers, its presence is assumed to be either a pleiotropic effect of the single flower gene, or to be controlled by an unidentified gene tightly linked with it.     

Inheritance of flower and pod colour in cowpea (Vigna unguiculata L. Walp.)

Inheritance of flower colour and pod colour in cowpea (Vigna unguiculata L. Walp.) has followed a qualitative pattern. Purple flower colour is dominant over white flower colour, whereas black pod colour is partially dominant over white pod colour. A segregation ratio of 3 purple:1 white flowers in F₂ generations of two crosses indicated that white flower colour is controlled by a single recessive. Segregation ratio of F₂ 1 white:2 light black:1 black indicated that black pod colour is partially dominant over white pod colour and is governed by one gene. These results were further confirmed by backcross generations. White flower and pod colour are controlled by single recessive genes on separate chromosome. Gene symbols were assigned. This revised version was published online in July 2006 with corrections to the Cover Date.     

Two outcrossing mechanisms in cowpeas,Vigna unguiculata (L.) Walp

Summary Several types of outcrossing mechanisms in cowpeas are observed in breeding plots at IITA. Two of these have been studied. One is genetic male sterility controlled by the simple recessive conditions of a gene designated as ms ₂ ms ₂. The other is mechanical male sterility involving petals constricted in such a way as to provide an opening for stigma and style to emerge at an early, pre-receptive stage of development; while simultaneously restricting stamen development. It is also inherited as a recessive character with the gene symbol designation of Cp-as normal and cp cp as constricted petal. The flower structure is unique and is easily recognized in large populations. Because fruit set is extremely poor it appears less promising than the genetic male sterility at present.     

Discovery of a new gene causing dark green cotyledons and pathway of pigment synthesis in lentil (Lens culinaris Medik)

A new gene is reported which functions as a master gene for synthesis of the pigments determining cotyledon colour in lentil. This gene is different from the two earlier reported genes which are responsible for synthesis of yellow (gene Y) and brown (gene B) pigments. Double recessive homozygous condition of these two genes results into loss of both pigments and, consequently, produces light green cotyledons. The new gene, in contrast, produces dark green cotyledons in recessive condition irrespective of the dominance or recessive state of the Y and B genes. It is hypothesized that the new gene for dark green cotyledon colour (Dg) acts at an earlier stage in the biosynthesis of the two cotyledon-specific pigments, which are derived from a common precursor, whose synthesis is blocked when Dg mutates to its recessive condition. This revised version was published online in August 2006 with corrections to the Cover Date.     

On the transmission of the yellow flower colour from Rosa foetida to recurrent flowering hybrid tea-roses

Summary To transfer the yellow flower colour of R. foetida to Hybrid Tea roses, F₁'s and backcrosses with Hybrid Tea's were produced. In B₁ populations, yellow, recurrent flowering seedlings occurred. Recurrent flowering was controlled by one recessive gene.     

Inheritance of fruit flesh and skin colours in powdery mildew resistant cucumbers (Cucumis sativus L.)

Summary The flesh of ripe cucumber fruits can show different colours, varying from intense or dingy white to yellow and orange. These colours appear to be governed by two genes, for which the symbols V and W are proposed. If both genes are recessive, an orange colour is produced; if both are dominant they give a dirty white colour. No linkage with the genes for mildew resistance could be demonstrated.A very strong linkage was observed between mildew resistance and a dull green exterior fruit colour governed by one gene for which the symbol D is proposed.     

The inheritance of apetalous flower type in Petunia hybrida Vilm. and linkage tests with the genes for flower doubleness and grandiflora characters and its use in hybrid seed production

Summary Genetic analysis of a mutant flower form in petunia in which the normal corolla tube was replaced by a second set of sepals (apetalous condition) was studied in F₁, F₂, F₃ and BC₁ generations after crossing with inbred normal flowered lines. Segregation patterns observed in these generations indicated that this mutant flower type was a monogenic recessive trait. The genes D for flower doubleness and G for grandiflora plant and flower character segregated independent of the apetalous character. The gene for apetalous flower character has been designated as apt.Michigan Agricultural Experiment Station Journal Article No 6272.     

Induced changes in growth and flowering of chrysanthemum after irradiation and in vitro culture of pedicels and petal epidermis

Summary To increase the genetic variation for yield in Chrysanthemum morifolium cv. White Spider, pedicel segments and petal epidermis were induced in vitro to regenerate adventitious buds either directly from the original tissue or indirectly via callus. Besides, pedicels were irradiated before in vitro culture with an X-ray dose of 8 Gy. All treatments yielded variation in flower morphology. Changes in flower colour were largely restricted to treatments involving irradiation.Treatments yielding many morphological variants also yielded most production variants. Plants regenerated from petals differed from those originating from pedicels. Clones were found that had retained the morphology of White Spider, but outperformed the controls in flowering time and flower number.     

Inheritance of neurotoxin (ODAP) content, flower and seed coat colour in grass pea (Lathyrus sativus L.)

Summary A strong epidemiological association is known to exist between the consumption of grass pea and lathyrism. A neurotoxin, -N-Oxalyl-L-, -diaminopropanoic acid (ODAP) has been identified as the causative principle. This study was undertaken to investigate the mode of inheritance of the neurotoxin ODAP, flower and seed coat colour in grass pea. Five grass pea lines with low to high ODAP concentration were inter-crossed in all possible combinations to study the inheritance of the neurotoxin. Parents, F₁ and F₂ progenies were evaluated under field condition and ODAP analyzed by an ortho-phthalaldehyde spectrophotometric method. Many of the progenies of low x low ODAP crosses were found to be low in ODAP concentration indicating the low ODAP lines shared some genes in common for seed ODAP content. The F₁ progenies of the low ODAP x high ODAP crosses were intermediate in ODAP concentration and the F₂ progenies segregated covering the entire parental range. This continuous variation, together with very close to normal distribution of the F₂ population both of low x low and low x high ODAP crosses indicated that ODAP content was quantitatively inherited. Reciprocal crosses, in some cases, produced different results indicating a maternal effect on ODAP concentration. Blue and white flower coloured lines of grass pea were inter-crossed to study the inheritance of flower colour. Blue flower colour was dominant over the white. The F₂ progenies segregated in a 13:3 ratio indicating involvement of two genes with inhibiting gene interactions. The gene symbol LB for blue flower colour and LW for white flower colour is proposed.     

Inheritance of flower colour and flavonoid pigments in Gerbera

The flower colour of Gerbera, an important ornamental cut flower, is derived from carotenoids and flavonoids. The knowledge of enzymological and genetic control of flavonoid biosynthesis is still incomplete. The present paper summarizes the results obtained at our institute between 1981 and 1993. The material for the investigation of phenotypic segregation and segregation of flavonoids after chromatographic analysis came from 408 progenies of controlled crosses. Phenotypic segregation analysis showed acyanic genotypes to be homozygous recessive and recessive epistatic over cyanic genotypes, respectively. This was confirmed by the existence of two loci controlling steps in biosynthesis (fht, dfr or ans) showing recessive mutants and complementary gene action after crosses. Flavone formation is effected by one dominant allele (fns⁺); dominant and recessive genotypes are now available. Regarding anthocyanidin inheritance, an unusual epistasis of 4′-hydroxylation (pelargonidin formation) over 3′,4′-hydroxylation (cyanidin formation) was observed. Final proof of the postulated gene actions will come from enzymological and molecular biological investigations of the chemogenetically defined Gerbera genotypes now available.     

利用花粉管通道法将查尔酮合酶基因导入仙客来

查尔酮合酶(chalcone synthase—A,CHSA)是花色素合成途径中的一个关键酶,它在植物中表达的量可能影响花的颜色。本项目从矮牵牛(Petunia hybrida)特定发育阶段的花瓣的cDNA中,克隆到查尔酮合酶基因CHSA,插入到含有花椰菜花叶病毒CaMV35S启动子的植物中间表达载体pBI12l和pWM101中,首次通过原位生殖系统导入法(具体采用花粉管通道法)转化仙客来,成功地得到4400余粒仙客来转化种子,8株白花植株的个别花瓣出现了黄斑或略显黄色,甚至个别花瓣变成了黄色花瓣：3株白花植株的个别花瓣一半变成了桃红色(二乔),甚至整个花朵完全变成了桃红色。转基因仙客来经PCR检测呈阳性。     

The increase of seed fertility of Brassicoraphanus through cytological irregularity

Summary Amphidiploids (Brassicoraphanus) were produced by means of colchicine treatment of F₁ hybrids between Brassica japonica Sieb. and Raphanus sativus L. The cytology of the amphidiploids was studied from F₁ to F₃ generations. Some plants had the euploid chromosome number 2n=38, whereas others had the aneuploid number 2n=37. One or two of either quadrivalents or trivalents, as well as some univalents, were seen in most of the plants examined. All the plants showed a low seed fertility. In F₃ generation there arose some yellow-flowered plants, all of which showed a higher seed fertility than normal white-flowered plants. It is postulated that the change of flower colour might originate in the segmental exchange of only partially homologous chromosomes following multivalent formation. A gene causing white flower colour was perhaps closely linked to a gene causing sterility, and both genes were probably excluded together through the segmental exchange of the chromosomes. Therefore, it can be said that the increase of fertility was induced by cytological irregularity.     

Trisomic genetic analysis of aroma in three Japanese native rice varieties (Oryza sativa L.)

Information on the genetics of aroma in rice facilitates breeding and selection of new aromatic varieties with high yield and good quality. Objective of the present study was to make clear the number of genes controlling aroma, and the allelism of aroma genes and the location of aroma gene(s) on the chromosome in three Japanese native aromatic rice varieties (Kabashiko, Shiroikichi and Henroyori). Lack of leaf aroma in all F₁ plants of non-aromatic/aromatic crosses indicated the recessive nature of aroma, and the segregation ratios (3:1) of non-aromatic to aromatic plants in its F₂ populations from Nipponbare/aromatic varieties crosses revealed that each of the three aromatic varieties contains a single recessive gene for aroma. Through trisomic analysis, the segregation of non-aromatic and aromatic plants in all F₂ populations from the crosses between trisomics lines NT8, with an extra chromosome 8, and aromatic varieties deviated significantly from disomic segregation of 3:1 ratios, and fitted to trisomic segregation, however, in other F₂ populations derived from other 7 types of trisomic F₁ plants, the segregation ratios of non-aromatic to aromatic were 3:1, indicating that the single recessive aroma gene was located on chromosome 8 in three aromatic varieties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigations on the inheritance of color and carotenoid content in phloem and xylem of carrot roots (Daucus carota L.)

Summary Investigations on the inheritance of root color in carrot (Daucus carota L.) were carried out by crossing uniformly colored roots to various tinge type roots, i.e. roots of which the xylem differs in color from the phloem.A single major gene (Y) was found to be responsible for the observed differences in progenies of orange x tinge orange-white (orange referring to phloem color, white to xylem color) crosses. Plants carrying the dominant Y-allele had either white or tinge orange-white roots, whereas plants with orange roots were of the genotype yy. Similarly one major gene (Y ₂) determined the segregation found in progenies of orange x yellow crosses. In the latter crosses, plants having the dominant Y ₂-allele had either yellow or tinge orange-yellow roots while the recessive would be orange. Variation in phloem color, i.e. differences between white and tinge orange-white or between yellow and tinge orange-yellow, was apparently caused by minor genes, modifiers, gene interactions, or by genes that are not involved in carotenogenesis in a direct way.When both the Y- and Y ₂-genes were present, the roots were always white. Usually white roots gave a digenic segregation pattern in the F₂ when crossed to orange, but there was some evidence that a third gene (Y ₁) was segregating in some crosses. Tinge orange-white x yellow crosses gave approximately the same results as orange x white crosses, confirming that the same Y- and Y ₂-genes were segregating.In crosses between orange lines and a light yellow line (RY) certain F₁ 's appeared to have a light orange xylem and a fairly dark orange phloem, which seems to be some evidence for the existence of recessive yellow. Although almost nothing is known yet about the genetics of RY it is assumed that it still carries a dominant inhibitor gene which may be leaky in heterozygous condition. The value of such a line as an aid in the selection of superior orange lines is discussed.Alpha- and beta-carotene were found to be the major pigments in orange carrot tissue; phytofluene, zetacarotene, gamma-carotene and xanthophylls were shown to be present in smaller amounts. Besides xanthophylls and a small amount of beta-carotene dark yellow carrot tissue appeared to contain an appreciable amount of an unidentified pigment (pigment I). Light yellow and white phloem or xylem tissue were low in total carotenoids.Research supported by the College of Agricultural and Life Sciences and by a grant from the Campbell Soup Company, Camden, New Jersey, USA. The investigation is a portion of a thesis submitted in 1978 as partial fulfillment of the requirements of the PhD degree.     

Genetics of seed coat colour in lentil

Summary Four grey mottled seed coat colour lentil lines/cultivars were crossed to one brown seed coat colour cultivar. The F₁ hybrids were brown seeded in all the crosses. Segregation pattern for seed coat colour in F₂ and F₃ generations revealed that it is under control of a single dominant gene, which is present in the parent UPL 175 while a recessive gene is responsible for grey mottled seed coat colour in Pant L 406, Pant L 639, LG 120 and Rau 101.     

Inheritance of closed flower in pepper

Summary Progenies of pepper (Capsicum annuum L.) crosses between the closed flower pepper line UFBG 8209-1 and cultivars Permagreen and Early Calwonder representing the normal, open flower type, were evaluated in a field experiment. The F₁ generation was open flowered. Backcrosses and F₂ generations indicated that the closed flower trait was controlled by a single recessive gene.Florida Agricultural Experiment Stations Journal Series No. 4918.     

Genetic analysis of gene‐specific resistance to mungbean yellow mosaic virus in mungbean (Vigna radiata)

Six intervarietal crosses involving two resistant and three susceptible genotypes of mungbean were attempted with the objectives to determine the mode of inheritance of gene‐specific Mungbean Yellow Mosaic Virus (MYMV) resistance. An infector row technique along with artificial inoculation was used for evaluating parents, F₁, F₂ and F₃ plants for MYMV resistance. Disease scoring for MYMV indicated that F₁s were highly susceptible as were the susceptible parents while resistant parent exhibited resistant reaction. The F₂ progeny segregated in the ratio of 9 S:3 MS:3 MR:1 R suggesting that the resistance was governed by digenic recessive genes (r_m1 and r_m2). When one gene (r_m1) was present in the homozygous recessive condition in different plants, it conferred moderately susceptible (MS) reaction, whereas when other gene (r_m2) was in homozygous condition, moderately resistant (MR) reaction was obvious. When both genes (r_m1 and r_m2) were present together in the homozygous recessive condition, resistant reaction (R) was observed. The F₂ segregation explained on the basis of phenotypic expression was further confirmed by F₃ segregation.