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.     

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.     

Inheritance of resistance to the chlorosis component of tan spot of wheat caused by Pyrenophora tritici-repentis, races 1 and 3

The fungus Pyrenophora tritici-repentis, causal agent of tan spot of wheat, produces two phenotypically distinct symptoms, tan necrosis and extensive chlorosis. The inheritance of resistance to chlorosis induced by P. tritici-repentis races 1 and 3 was studied in crosses between common wheat resistant genotypes Erik, Hadden, Red Chief, Glenlea, and 86ISMN 2137 and susceptible genotype 6B-365. Plants were inoculated under controlled environmental conditions at the two-leaf stage and disease rating was based on presence or absence of chlorosis. In all the resistant × susceptible crosses, F₁ plants were resistant and the segregation of the F₂ generation and F₃ families indicated that a single dominant gene controlled resistance. Lack of segregation in a partial diallel series of crosses among the resistant genotypes tested with race 3␣indicated that the resistant genotypes possessed␣the same resistance gene. This resistance gene was effective against chlorosis induced by P.␣tritici-repentis races 1 and 3.     

Genetic control of boron efficiency in wheat (Triticum aestivum L.)

The genetic control of boron (B) efficiencyin wheat (Triticum aestivum L.) wasstudied for three genotypes representing Binefficient (I, Bonza), moderately Binefficient (MI, SW 41) and B efficient (E,Fang 60) categories. Boron efficiency wasexpressed as a partially dominant characterbut the phenotypes of F₁ hybrids,relative to parents, indicated geneticcontrol varying from recessive to additiveto completely dominant with different crosscombinations and B levels. Major geneswere identified from the evaluation ofF₂-derived F₃ populations derivedfrom intercrosses between the threeparents. Monogenic segregation was foundin Bonza × SW 41 and SW 41 × Fang 60crosses and digenic segregation resultedin Bonza × Fang 60. Among thethree wheat genotypes with widely differentB efficiency, genetic variation forresponse to B could be accounted for by twogenes, Bo _d 1 and Bo _d 2.     

Models of inheritance of flower colour and extra petals in Potentilla fruticosa L.

Summary Inheritance models for flower colour and extra petals in Potentilla fruticosa L. were developed by conducting controlled crosses between different cultivars and advanced selections. Parents were crossed in all combinations and floral character segregation of progenies were recorded. Preliminary models for flower colour include two whitening genes (W₁ and W₂) and two yellowing genes (Y₁ and Y₂) with the action of a bleaching gene also implicated. The cyanic flower colour model developed involves background petal colour, cyanic pigments and distribution and temperature sensitivity genes. The extra petals model involves a two gene switch, D₁ and D₂ to turn on the production of up to five extra petals and a modifier gene, D_m that accounts for an additional one to five extra petals. Either D₁ or D₂ must be recessive to initiate extra petal production. D_m must also be recessive to enable production of an additional 1–5 petals.     

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.     

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 heading time in spring barley evaluated in multiple environments

The inheritance of heading time of spring barley was studied in three extremely early genotypes IB, RL and ‘Mona’ (M), which is homozygous recessive for the early maturity ea8 (=ea_k) gene conferring extreme earliness under short daylengths and is relatively photoperiod insensitive, and five (GP, MA, PS, NU and BA) spring genotypes that are early to intermediate for heading time. Frequency distributions of F₂ generations grown at Ouled Gnaou, Morocco (32°15′ N), an environment which maximizes differences between photoperiod‐insensitive and photoperiod‐sensitive genotypes, indicated that across populations many loci were segregating in a complex Mendelian manner. IB and RL were both homozygous recessive for the ea8 gene, which conferred an early heading time. RL had partially dominant alleles at second locus (Enea8), which enhanced its earliness. Recovery of only progeny within the parental range of genotypes for heading time from the crosses of RL/M and IB/M suggests that numerous loci remained suppressed, perhaps latent, given their diverse parentage. The ea8 recessive homozygote in RL suppressed another unidentified locus which, when homozygous recessive in the absence of the ea8 recessive homozygote, conferred extreme earliness in one short daylength environment (Ouled Gnaou, Morocco) but was undetected in another environment (Davis, CA, USA). Epistatic gene action and genotype × environment effects strongly influenced heading time. In addition to a genetic system consisting of single‐locus recessive homozygotes conferring photoperiod insensitivity, a second genetic system, based on dominant alleles at one or a few loci, derived from the early heading Finnish landrace ‘Olli’, also confers extremely early heading time under short daylengths and relative photoperiod insensitivity in the genotype GP.     

Linkage relationships of some genes for disease and insect resistance and semidwarf stature in rice

Summary Two-way classification of 400 F₃ families from the rice cross IR2153-159-1 x Babawee for plant stature and for resistance to brown planthopper, green leafhopper, and bacterial blight indicated that Glh 3 (dominant gene for resistance to green leafhopper) and bph 4 (recessive gene for resistance to brown planthopper) are linked with a map distance of 34 units. The bph 4 gene also appears to be linked with sd ₁ (recessive gene for semidwarf stature) although the linkage is less strong. However, bph 4 and Xa 4 (dominant gene for bacterial blight resistance) are inherited independently of each other. No segregation for susceptibility was observed among F₃ families of crosses between varieties having Bph 3 and bph 4 genes for resistance to brown planthopper. Apparently, Bph 3 and bph 4 are either allelic or closely linked.     

Inheritance of temperature sensitivity of the photoperiod response in common bean (Phaseolus vulgaris L.)

Summary Photoperiod response of flowering in common bean (Phaseolus vulgaris L.) is thought to be controlled by the genes Ppd and Hr. However, cultivars also vary in the degree that cooler temperatures reduces their sensitivity to photoperiod. To examine the inheritance of this temperature sensitivity, crosses of cvs. Gordo x de Celaya and Flor de Mayo × Rojo 70 were evaluated at two sites differing in mean temperature and using 12.5-h natural photoperiod or 18-h artificially extended photoperiod. Under 18-h photoperiod at the warmer site, Palmira, no plants of the parents or of the F₂ populations flowered, confirming that the parents were sensitive to photoperiod. Under 12.5-h photoperiod at the cooler site, Popayan, the parents for each cross flowered at similar dates and no segregation for days to flower was observed. However, under 18-h photoperiod, de Celaya and Rojo 70 and the F₁ populations did not flower within 100 days after planting, while the F₂ and F₃ populations showed segregation that was consistent with single gene inheritance, late flowering being dominant. Late flowering at Popayan under 18-h photoperiod indicates a lack of temperature sensitivity, so temperature insensitivity of the photoperiod response was dominant to sensitivity. The name Tip, for temperature insensitivity of photoperiod response, is proposed for this gene, with the recessive form of this gene conditioning earlier flowering at cooler temperatures with long daylengths. It is recognized that the observed segregation patterns could represent the effect of multiple alleles at the Ppd or Hr loci, and studies are proposed to test this possibility with molecular markers and recombinant inbred lines.     

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.     

Resistance to Ascochyta blight in chickpea - Genetic basis

Summary Genetic regulation of host resistance in chickpea-Ascochyta rabiei interaction system is governed by two dominant complementary genes each in the genotypes GLG 84038 and GL 84099, whereas the resistance in a black seeded genotype ICC 1468 was controlled by one dominant and one recessive independent gene. In all the genotypes, resistance is operated by inter-allelic interactions. The genes conferring resistance in GLG 84038 were found to be different to those operating in GL 84099 and ICC 1468. Among the five dominant genes dispersed in 3 genotypes under study, at least one has been reported for the first time, as to date, only three dominant genes have been reported in the literature.The four identified dominant genes in GLG 84038 and GL 84099 have been named as Arc₁, Arc₂ (in GLG 84038) and Arc₃, Arc₄ (in GL 84099). The undistinguished dominant gene in ICC 1468 has been named as Arc_5(3,4) as it could not be equated or differentiated from Arc₃ or Arc₄. The recessive gene in ICC 1468 has been named as Arc₁.Generation mean analysis of the 6 resistant × susceptible crosses involving the same genotypes, revealed that the genes conferring resistance in any of the 3 genotypes did not follow simple Mendelian inheritance but were influenced by inter allelic interactions. Additive gene effect along with dominance were operative in all the 3 genotypes under study in conferring resistance. However, the mechanism of resistance in GLG 84038 and GL 84099 were primarily additive in nature while that in ICC 1468, dominance as well as dominance × dominance interactions were more important than additive gene action.     

Inheritance and allelic relationship among gene(s) for blast resistance in pearl millet [Pennisetum glaucum (L.) R. Br.]

Six blast‐resistant pearl millet genotypes, ICMB 93333, ICMB 97222, ICMR 06444, ICMR 06222, ICMR 11003 and IP 21187‐P1, were crossed with two susceptible genotypes, ICMB 95444 and ICMB 89111 to generate F₁s, F₂s and backcrosses, BC₁P₁ (susceptible parent × F₁) and BC₁P₂ (resistant parent × F₁) for inheritance study. The resistant genotypes were crossed among themselves in half diallel to generate F₁s and F₂s for test of allelism. The F₁, F₂ and backcross generations, and their parents were screened in a glasshouse against Magnaporthe grisea isolates Pg 45 and Pg 53. The reaction of the F₁s, segregation pattern of F₂s and BC₁P₁ derived from crosses involving two susceptible parents and six resistant parents revealed the presence of single dominant gene governing resistance in the resistant genotypes. No segregation for blast reaction was observed in the F₂s derived from the crosses of resistant × resistant parents. The resistance reaction of these F₂s indicated that single dominant gene conferring resistance in the six genotypes is allelic, that is same gene imparts blast resistance in these genotypes to M. grisea isolates.     

Inheritance of Resistance to Yellow Mosaic Virus in some Vigna Species

Inheritance of resistance to Yellow Mosaic Virus (YMV) was studied in crosses of mungbean, black-gram and their interspecific crosses with Vigna sub-lobata. Resistance to YMV was recessive in the three Vigna species. The segregation ratios in F₂ and back crosses indicated that the resistance was digenic recessive in the crosses of mungbean and in interspecific crosses of mungbean with blackgram and Vigna subiobata but YMV resistance was monogenic recessive in blackgram crosses.     

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.     

Genetic analysis of karnal bunt resistance in 14 Mexican bread-wheat genotypes

Fourteen Mexican genotypes of bread wheat (Triticum aestivum L.) with good to moderate levels of resistance to Karnal bunt (Tilletia indica (Mitra)) were crossed with the highly susceptible cultivar WL711 to determine the genetic basis of resistance. The parents, F₁ F₂ and backcross populations of the 14 crosses were evaluated under artificial epiphytotic conditions during the 1993–94 season for Karnal bunt resistance. The F₁ data suggested that the resistance was dominant to partially dominant over susceptibility. The F₂ analysis of the segregation ratios in the F₂ and backcross generations indicated that the resistance in the wheat genotypes Luan, Attila, Vee #7/Bow, Star, Weaver, Milan, Sasia and Turacio/Chil is controlled by two genes. The resistance in genotypes Cettia, Irena, Turaco, Opata, Picus, and Yaco was found to be conditioned by a single dominant gene. The genotypes with two genes for resistance expressed a higher level of resistance than those with a single gene and, therefore, are better sources of resistance to Karnal bunt.     

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.     

Inheritance of resistance and genetic relationships among soybean plant introductions to races of soybean cyst nematode

Summary The objectives of this study were to determine if genes for resistance to soybean cyst nematode (SCN) in soybean PI 437654 were identical or different from the genes in Peking, and PI 90763. The F₂ plants and F₃ families were studied from crosses between PI 437654, Peking, and PI 90763. The cross PI 437654 × susceptible Essex was included to determine inheritance of resistance to SCN. For Race 3, PI 437654 was found to have genes in common with Peking and PI 90763. The segregation in PI 437654 × Essex indicated the presence of one dominant and two recessive genes. For Race 5, PI 437654 indicated the presence of similar genes as those in PI 90763 and Peking whereas, PI 437654 × Essex indicated the action of the segregation ratios of two dominant and two recessive genes. For Race 14, the data from the cross PI 437654 × PI 90763 indicated monogenic inheritance with resistance being dominant; whereas PI 437654 × Peking showed a recessive gene controlling resistance. The segregation in PI 437654(R) × Essex(S) suggested one dominant and two recessive genes for Race 14 reaction.     

Identification and Genetic Studies of the Inhibition of Dominant Male Sterility in Brassica napus

By transferring dominant male sterility (DMS), caused by the gene Ms, to genotypes with various types of cytoplasm 12 DMS lines were developed and a number of crosses made between the DMS lines and other genotypes of Brassica napus. During the course of this population improvement programme, 16 genotypes were identified as having the capacity to restore the fertility of F₁ plants with the Ms gene. According to pedigree analysis, the inhibitory gene in those lines probably originated from a few genotypes from Australia and Germany. In further studies the inheritance of the sterility inhibition was determined, providing definite evidence that dominant male sterility and its inhibition in B. napus are controlled by two dominant interacting genes rather than by multiple alleles.     

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.