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.     

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.     

Inheritance of siliqua locule number and seed coat colour in Brassica juncea

The inheritance of siliqua locule number and seed coat colour in Brassica juncea was investigated, using three lines each of tetralocular brown seeded and bilocular yellow seeded. Three crosses of tetralocular brown seeded × bilocular yellow seeded lines were attempted and their F₁, F₂ and backcross generations were examined for segregation of these two traits. Brown seed colour and bilocular siliqua characters were found to be dominant over yellow seed and tetralocular siliqua, respectively. Chi‐square tests indicated that each trait is controlled by different sets of duplicate pairs of genes. Bilocular siliquae or brown seeds can result from the presence of either of two dominant alleles, whereas tetralocular siliquae or yellow seeds are produced when alleles at both loci are recessive. A joint segregation analysis of F₂ data indicated that the genes governing siliqua locule number and seed colour were inherited independently.     

Inheritance of siliqua orientation and seed coat colour in Brassica tournefortii

The inheritance of siliqua orientation and seed coat colour in Brassica tournefortii was investigated using four genotypes varying in these two characters. The F₁, F₂ and backcross generations of two crosses were used for studying the segregation pattern of the traits. The plants were classified for seed colour as having brown or yellow seeds and for siliqua orientation as having upright, semi‐spread or spread siliqua. Seed colour was found to be under monogenic control with brown being dominant over yellow. Siliqua orientation was under digenic polymeric gene action: upright siliqua was produced by the presence of two dominant genes and spread siliqua by two recessive genes. The absence of even a single dominant gene resulted in a third type of siliqua orientation, semi‐spread siliqua.     

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.     

Independent Inheritance of Flower Colour and Male-Fertility Restorer Characters in Brassica napus L.

Available material of oilseed (Brassica napus L., AACC) comprises two yellow-flowered breeding lines and a white/pale-flowered line of resynthesized rape. The flower colour white/pale is dominant over yellow, and is controlled by a gene located in the C-genome. The yellow-flowered genotypes acted as restorer lines and the white/pale-flowered genotype as a maintainer line in a cytoplasmic male sterility system. The segregation pattern of flower colour and male fertility restorer characters were studied in F₂ generations of crosses between these lines, also in a three-way cross additionally including a yellow flowered B. campestris (AA) line. Evidense was obtained in support of the conclusion that the flower colour and male fertility restorer characters are monogenically controlled and independently inherited. Whether the male fertility restorer gene is located in the A or C genome remains to be determined.     

Genetic characterization of the red coloured corolla phenotype for Gossypium arboreum accession PI 529731

Flower corolla colour is an important trait for the attraction of pollinators and for the horticultural industry. Gossypium arboreum (L.) accessions from the United States Department of Agriculture germplasm collection frequently show flowers with a yellow coloured corolla. Accession PI 529731 is unique in that the flowers have a red coloured corolla. Genetic characterization of corolla pigmentation was conducted by crossing PI 529731 with two white flower accessions. Flowers with a red corolla were observed in the F₁ generations suggesting a dominant trait. Variation in corolla colour was observed for plants in the F₂ populations including dark red, red, light red, white, yellow and white with petals having red coloured margins. These data support a single dominant gene conferring the four red corolla phenotypes. The yellow corolla phenotype also supported a single dominant gene model. Dominant alleles at both loci are required for expression of the PI 529731 phenotype and data support a two gene model with a 9:3:3:1 segregation ratio. These data are useful for the characterization of genetic mechanisms controlling tissue‐specific pigmentation.     

Identification and inheritance of a partially dominant gene for yellow seed colour in Brassica napus

A yellow‐seeded doubled haploid (DH) line no. 2127‐17, derived from a resynthesized Brassica napus L., was crossed with two black‐seeded Brassica cultivars ‘Quantum’ and ‘Sprint’ of spring type. The inheritance of seed colour was investigated in the F₂, and BC1 populations of the two crosses and also in the DH population derived from the F1 of the cross ‘Quantum’× no. 2127‐17. Seed colour analysis was performed with the colorimeter CR‐300 (Minolta, Japan) together with a visual classification system. The immediate F1 seeds of the reciprocals in the two crosses had the same colour as the self‐pollinated seeds of the respective black‐ and yellow‐seeded female parents, indicating the maternal control of seed colour. The F1 plants produced yellow‐brown seeds that were darker in colour than the seeds of no. 2127‐17, indicating the partial dominance of yellow seed over black. In the segregating BC1 progenies of the two crosses, the frequencies of the black‐ and yellow‐seeded plants fit well with a 1 : 1 ratio. In the cross with ‘Quantum’, the frequencies of yellow‐seeded and black‐seeded plants fit with a 13 : 3 ratio in the F₂ progeny, and with a 3 : 1 ratio in the DH progeny. However, a 49 : 15 segregation ratio was observed for the yellow‐seeded and black‐seeded plants in the F₂ progeny of the cross with ‘Sprint’. It was postulated from these results that seed colour was controlled by three pairs of genes. A dominant yellow‐seeded gene (Y) was identified in no. 2127‐17 that had epistatic effects on the two independent dominant black‐seeded genes (B and C), thereby inhibiting the biosynthesis of seed coat pigments.     

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 black testa colour in lentil (Lens culinaris Medik.)

The inheritance of testa (seed coat) colour and interaction of cotyledon and testa colours were studied in seven crosses of lentil (Lens culinaris Medik.) involving parents with black, brown, tan or green testa and with orange, yellow or dark green cotyledons. Analysis of F₂ and F₃ seed harvested from F₁ and F₂ plants, respectively, revealed that although black testa is dominant over nonblack testa, its penetrance is not complete since both F₁ plants and heterozygous F₂ plants produced varying proportions of seeds with either black or nonblack testa. The F₂ populations of the crosses between parents with brown and tan, as well as brown and green, testa segregated in the ratio of 3 brown : 1 tan and 3 brown : 1 green, respectively, indicating monogenic dominance of brown testa colour over tan or green. The expression of testa colour was influenced by cotyledon colour when parents with brown or green testa are crossed with those having orange or green cotyledons. Thus F₂ seeds from these crosses with a green testa always had green cotyledons and never orange cotyledons. F₂ seeds from these crosses with a brown testa always had orange cotyledons and never green cotyledons. These results suggest diffusion of a soluble pigment from the cotyledons to the testa. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

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.     

Independent Inheritance of Erucic Acid Content and Flower Colour in the C-Genome of Brassica napus L.

The synthetic Brassica napus L. line No7076 was obtained from a cross between yellow-flowered and zero-erucic turnip rape (B. campestris) Sv85-38301 and white-flowered and high-erucic (41.4%) B. oleracea ssp. alboglabra No6510. This synthetic B. napus is pale-flowered and has an average erucic acid content of 25.8 %. It was crossed with the yellow-flowered and zero-erucic B. napus line SvS4-2S053 and segregation of the erucic acid content and flower colour was studied in F₁ and F₂ generations. The high erucic acid content was controlled by a single gene in the C-genome and was additively inherited. Strong evidence was obtained in support of independent segregation of the erucic-arid content and the flower colour characters controlled by the C-genome of B. napus.     

Inheritance of trichomes and resistance to pod borer (Helicoverpa armigera) and their association in interspecific crosses between cultivated pigeonpea (Cajanus cajan) and its wild relative C. scarabaeoides

The legume pod borer, Helicoverpa armigera, is one of the most devastating pests of pigeonpea. High levels of resistance to pod borer have been reported in the wild relative of pigeonpea, Cajanus scarabaeoides. Trichomes (their type, orientation, density and length) and their exudates on pod wall surface play an important role in the ovipositional behavior and host selection process of insect herbivores. They have been widely exploited as an insect defense mechanism in number of crops. In the present investigation, inheritance of resistance to pod borer and different types of trichomes (A, B, C and D) on the pod wall surface in the parents (C. cajan and C. scarabaeoides) and their F₁, F₂, BC₁ (C. cajan × F₁), and F₃ generations has been studied. Trichomes of the wild parents (high density of the non-glandular trichomes C and D, and glandular trichome B and low density of glandular trichome A) were dominant over the trichome features of C. cajan. A single dominant gene as indicated by the segregation patterns individually will govern each trait in the F₂ and backcross generation. Segregation ratio of 3 (resistant): 1 (susceptible) for resistance to pod borer in the F₂ generation under field conditions was corroborated with a ratio of 1:1 in the backcross generation, and the ratio of 1 non-segregating (resistant): 2 segregating (3 resistant: 1 susceptible): 1 non-segregating (susceptible) in F₃ generation. Similar results were obtained for pod borer resistance under no-choice conditions. Resistance to pod borer and trichomes associated with it (low density of type A trichome and high density of type C) are governed individually by a dominant allele of a single gene in C. scarabaeoides. Following backcrossing, these traits can be transferred from C. scarabaeoides into the cultivated background.     

Inheritance of seed colour in Brassica campestris L. and breeding for yellow-seeded B. napus L.

Summary Seed colour inheritance was studied in five yellow-seeded and one black-seeded B. campestris accessions. Diallel crosses between the yellow-seeded types indicated that the four var. yellow sarson accessions of Indian origin had the same genotype for seed colour but were different from the Swedish yellow-seeded breeding line. Black seed colour was dominant over yellow. The segregation patterns for seed colour in F₂ (Including reciprocals) and BC₁ (backcross of F₁ to the yellow-seeded parent) indicated that the black seed colour was conditioned by a single dominant gene. Seed colour was mainly controlled by the maternal genotype but influenced by the interplay between the maternal and endosperm and/or embryonic genotypes. For developing yellow-seeded B. napus genotypes, resynthesized B. napus lines containing genes for yellow seed (Chen et al., 1988) were crossed with B. napus of yellow/brown seeds, or with yellow-seeded B. carinata. Yellow-seeded F₂ plants were found in the crosses that involved the B. napus breeding line. However, this yellow-seeded character did not breed true up to F₄. Crosses between a yellow-seeded F₃ plant and a monogenomically controlled black-seeded B. napus line of resynthesized origin revealed that the black-seeded trait in the B. alboglabra genome was possibly governed by two independently dominant genes with duplicated effect. Crossability between the resynthesized B. napus lines as female and B. carinata as male was fairly high. The sterility of the F₁ plants prevented further breeding progress for developing yellow-seeded B. napus by this strategy.     

Inheritance of growth vigour and its association with other characters in chickpea

Growth vigour plays an important role in the establishment of a normal crop. The F₂ population of a cross between high‐ and low‐growth vigour varieties of chickpea segregated into 15 high : 1 low growth vigour. The results for recombinant inbred lines and BC1P₂ showed a good fit to the expected 3 : 1 ratio. The results indicated that growth vigour is controlled by two genes with duplicate dominant epistasis. No gene has so far been identified for growth vigour in chickpea. Correlation between growth vigour and other characters showed that high growth vigour had significant negative correlation with days to first flower, days to 50% flowering, days to first pod and days to maturity.     

Development of yellow-seeded Brassica napus of double low quality

Two yellow‐seeded white‐petalled Brassica napus F₇ inbred lines, developed from interspecific crosses, containing 26–28% emcic acid and more than 40 μmol glucosinolates (GLS)/g seed were crossed with two black/dark brown seeded B. napus varieties of double low quality and 287 doubled haploid (DH) lines were produced. The segregation in the DH lines indicated that three to four gene loci are involved in the determination of seed colour, and yellow seeds are formed when all alleles in all loci are in the homozygous recessive state. A dominant gene governed white petal colour and is linked with an erucic acid allele that, in the homozygous condition, produces 26–28% erucic acid. Four gene loci are involved in the control of total GLS content where low GLS was due to the presence of recessive alleles in the homozygous condition in all loci. From the DH breeding population a yellow‐seeded, yellow‐petalled, zero erucic acid line was obtained. This line was further crossed with conventional B. napus varieties of double low quality and, following pedigree selection, a yellow seeded B. napus of double low quality was obtained. The yellow seeds had higher oil plus protein content and lower fibre content than black seeds. A reduction of the concentration of chromogenic substances was found in the transparent seed coat of the yellow‐seeded B. napus.     

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.     

Inheritance of siliqua characters in Indian colza I. Locule number and siliqua position

Summary F₁, F₂, BC₁ and BC₂ generations, involving bilocular and tetralocular siliquae and with upright and pendent siliqua position, were studied with their parents. The segregation pattern in these generations indicated that number of locules is monogenically governed with the allel for bilocular type (VV-two valved pods) showing complete dominance over tetralocular (vv). Upright siliqua position is governed by two dominant genes (Up₁ Up₁ Up₂ Up₂) and pendent by two recessive genes (up₁ up₁ up₂ up₂). However, in absence of even a single dominant gene it give rise to a third type of siliqua position i.e. parallel.     

Chasmogamous mutant,a novel character enabling commercial hybrid seed production in mungbean

Mungbean (Vigna radiata (L.) Wilczek) is a self-pollinating crop that displays significant hybrid vigor in seed yield of F₁ hybrids. Thus there is the possibility to use hybrid varieties as a breakthrough to raise the yield plateau of mungbean. However, hybrid mungbean seeds can only be accomplished by hand-pollination and thus commercial production is not possible. To encourage hybrid seed set, the plant breeder needs to develop characters that promote higher outcrossing rate such as open flower (chasmogamy). In this experiment, new chasmogamous mutants were induced by gamma irradiation at the rate of 100 and 200 Gy. The mutants were identified at a low rate of 0.4–0.7% in the M₂ generation of accession V1197, and observed for their purity by growing in plant-to-row in the M₃ and M₄ generations. A uniform chasmogamous line was hybridized to normal flower lines to study the inheritance of this character. All F₁ plants had normal flowers, while the F₂ plants segregated well with 3 normal : 1 chasmogamous ratio. When the F₁ was backcrossed to the chasmogamous parent, the progeny gave a ratio of 1 normal to 1 chasmogamous. Thus, chasmogamy was controlled by a single recessive gene, cha.