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 and agronomic performance of an apetalous flower mutant in Brassica napus L

A spontaneous mutant with apetalous flowers was obtained from a hybrid progeny in Brassica napus. The result of genetic analysis showed that the apetalous character was controlled by only one gene locus, petalous flower exhibited incomplete dominance over apetalous flower and that its expression was not affected by cytoplasmic factors. Sixteen agronomically important characteristics of the apetalous line Apet33-10 were compared with those of its petalled near-isogenic line Pet33-10. Results from 4 years of tests indicated that there was no difference between Apet33-10 and Pet33-10 in all tested agronomic characteristics, except for the pod number of main inflorescence and second-order branches at low sclerotinia disease incidence. The Sclerotinia sclerotiorum disease severity index of Apet33-10 was significantly lower than that of Pet33-10, and correspondingly, the plot yield of Apet33-10 was increased obviously in comparison to that of Pet33-10 if sclerotinia disease was serious. The pod number of main inflorescence of Apet33-10 was significantly lower than that of Pet33-10. On the other hand, the pod number of second-order branches of Apet33-10 was significantly higher than that of Pet33-10, hence no overage difference of the pod number per plant was observed between the two lines.     

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.     

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.     

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.     

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 trichome density in Ethiopian mustard leaves

A pubescent mutant of Ethiopian mustard (Brassica carinata A. Braun), N2-9531, was developed from the glabrous line C-101. The objective of this research was to study the inheritance of trichome density in this mutant. Plants of N2-9531 and C-101 were reciprocally crossed and F₁, F₂, and BC₁F₁ generations were analysed for trichome density. The average trichome density differed in the reciprocal F₁ and F₂ generations, indicating partial cytoplasmic effects. The trichome density of F₁ plants was lower than the midparent value, revealing a partial dominance of absence over high trichome density. Segregation in the F₂ and BC₁F₁ generations approximated 1:4:6:4:1 and 1:2:1 ratios, respectively indicating that two independent loci (H ₁ and H ₂) acting in an additive manner contributed equally to the expression of trichome density. The proposed genotypes were h ₁ h ₁ h ₂ h ₂ for N2-9531 and H ₁ H ₁ H ₂ H ₂ for C-101. The simple inheritance of this trait should facilitate the transfer of leaf pubescence to other Ethiopian mustard lines. This revised version was published online in July 2006 with corrections to the Cover Date.     

The inheritance of the naked grain character in oats studied in a cross between the naked variety caesar and the husked variety BO 1/11

Summary The inheritance of the naked grain character in oats was studied in a cross between BO 1/11 (husked) and Caesar (naked), by analysing plants of F₁, F₂, F₃ and both (F₁ × BO 1/11) and (F₁ × Caesar) backcross generations. F₁ and F₂ plants were grown under both glasshouse and field conditions.Results suggest that the naked/husked character is basically governed by one major gene and modifying genes mask the effect of the main gene in the homozygous naked and heterozygous classes.Expression of the naked grain character was higher under glasshouse than under field conditions, indicating the large influence which environment can exert on the expression of this character.     

Variation of harvest index in several wheat crosses

Summary Harvest index was studied in F₁ and F₂ generations of eight wheat (Triticum aestivum L.) crosses and their reciprocals. The parental varieties involved in the crosses represented a fairly wide range of character expression for plant height, tillering potential, grain yield per plant and harvest index. Differences between reciprocal crosses were not evident for the expression of harvest index of the crosses under study. Means and degrees of dominance of F₁ and F₂ populations suggested partial dominance of high harvest index over low harvest index. The pattern of variation among F₂ segregates was quantitative and the distribution was normal. The gene action governing the expression of harvest index was largely additive. Evidence was obtained for non-additive gene action in some crosses. There was complete absence of high parent heterosis for harvest index in the F₁'s but midparent heterosis was found to be present in all crosses. Estimates of heritability and genetic advance were moderate to high. Usefulness of selecting for harvest index as a measure of yield efficiency particularly in early generations is discussed.     

Mode of inheritance of Alcobaca,a tomato fruit-ripening mutant

Summary Alcobaca, an abnormally ripening tomato mutant, was crossed with the normal cultivar Rutgers. Examination of F₁, F₂ and BC₁ populations indicated that a single recessive gene controls the mutant phenotype. No maternal effect was detected.     

Potentialities of heterosis breeding in wheat

Summary Heterosis for yield and yield components were studied in F₁, F₂ and F₃ generations in ten crosses of wheat, Triticum aestivum L., under normal spacing. Eighty and 60% F₁ hybrids exceeded the high parent and standard variety to the extent of 44.3 and 36.4 per cent. respectively. The two best crosses excelled the high parent and the standard variety by a significant margin. The result showed that seed of advanced generations cannot be used for commercial wheat production, Heterosis in yield seems to be reflected through heterosis in spike number and 1000-kernel weight. In general it was found that the greater the genetic difference of the parents with a high yield capacity the better are their hybrids.     

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.     

The inheritance of flower colour and vegetative characters in Rubus coreanus

Summary Dominant genes An ₁ for pink flower colour and Br ₁ and Br ₂ controlling branching of the canes in Rubus coreanus are described. In an F₁ progeny and in first backcrosses to red raspberry, some seedlings inherited the ability of R. coreanus to form up to three accessory buds per node. Polygenic systems controlling spine number and spine size are described, number and size being positively correlated. It is postulated that the greater size of spines of h (glabrous-caned) plants is due to linkage of a block of size-controlling genes with the H locus. The greater number of spines of H (hairy-caned) plants is attributed to a pleiotropic effect of the H allele. A new type of dwarf, cauli-flower, which occurred in the F₁ and some first backcross progenies, is described.     

The inheritance of resistance to blue mold (Peronospora tabacina Adam) in two cultivars of tobacco (Nicotiana tabacum L.)

Summary Two blue-mold resistant cultivars of Nicotiana tabacum L. were crossed with each other and with the susceptible Israeli local cultivar Mikhal. F₁, F₂ and F₃ progenies of these crosses, F₁ and F₂ of backcrosses and the parental varieties were grown in a series of experiments, in which the seedlings were exposed to heavy natural infection with Peronospora tabacina Adam. The genetic basis of resistance was found to be identical in the two resistant strains Bel-61-10 and Chemical mutant. A single dominant major gene determined the segregation of resistance versus susceptibility in the crosses of these strains with Mikhal. The level of resistance of resistant segregates was shifted by environment and by quantitatively modifying genes. The index of resistance, which was calculated as a weighted mean of the degree of blue-mold expression of the resistant segregates, differed in the generations of cross progeny. This could be explained by the different expected levels of the modifying genes in these generations. Heritability of the index of resistance was calculated by parent-offspring regression and it was found to be 0.542 in the F₃ and 0.227 in F₂ backcross progenies.     

Genetic effects of the soft starch (h) and background loci on volume of starch granules in five inbreds of maize

Larger particle volume is beneficial for many aspects of maize starch processing, and may improve the performance of some starch attributes. This study focused on the soft starch (h) locus to identify its potentially influential role in starch particle volume distribution. The objectives were to study the genetic expression of starch particle volume of the h locus in different genetic backgrounds and the gene action conditioning starch particle volume of other loci in both normal‐starch and h‐starch backgrounds. Forty‐five populations (five intra‐inbred F_1s, 10 hybrid F_1s 10 F_2s, 10 BC₁F_1s to h/h parent, and 10 BC₁ to h:h conversion of normal parent) were planted in 1993 at two locations and in 1995 at one location. Selfed heterozygotes (±/h) in all generations provided intra‐ear comparisons of normal and h starch, and F₃ and BC₁F₂ generations provided inter‐ear comparisons. Significant differences were found between normal and h:h genotypes in all intra‐ear and inter‐ear comparisons. In all cases, general combining ability effects were highly significant, suggesting the presence of additive gene effects. Generation mean analysis of normal and h:h starch materials yielded similar results, indicating the predominance of additive and some dominance effects for other loci on starch particle volume. These results indicate the usefulness of the soft starch gene and additional genetic variation among inbreds in the improvement of starch particle volume for increased starch recovery in wet milling.     

Inheritance of very high linoleic acid content and its relationship with nuclear male sterility in safflower

Safflower (Carthamus tinctorius L.) possesses the highest amount of linoleic acid among the 10 major vegetable oil crops of the world. Very high linoleic acid content is controlled by recessive alleles at a single locus Li. However, deviated segregations from the expected monogenic inheritance have been observed in crosses involving nuclear male‐sterile (NMS) lines. The present research was undertaken to study the inheritance of very high linoleic acid content in safflower and its relationship with nuclear male sterility. F₁, F₂, F₃, BC₁F₁ and BC₁F₂ seed generations were evaluated in a cross between CR‐142 (a line with very high linoleic acid content, 88%) and CL1 (an NMS line with wild‐type linoleic acid content, 74%). The genetics of linoleic acid content in male‐sterile plants was determined by testcrossing with CR‐142. The results confirmed monogenic inheritance. The analysis of the F₃ and BC₁F₂ to CL1 seed generations demonstrated a repulsion‐phase linkage between Li and Ms loci, the latter conferring the NMS trait. The recombination rate between Li and Ms was estimated to be 0.09.     

Genetics of grains per spike in durum wheat under normal and late planting conditions

Parental, F₁, F₂, BC₁, BC₂, BC₁₁, BC₁₂, BC₂₁, BC₂₂, BC₁ self and BC₂ selfed generations of three crosses involving six cultivars of durum wheat (Triticum durum Desf.) were studied for grains per spike under normal and late sown environments to analyze the nature of gene effects. A 10-parameter model did not fully account for the differences among the generation means. In two cases more complex interactions or linkage were involved in the inheritance of grains per spike in durum. Both digenic and trigenic epistatic interactions had a role in controlling the inheritance of grains per spike, however, trigenic interactions contributed more than digenic interactions. Non-fixable gene effects were many times higher than fixable ones in all three crosses and in both sowing environments indicating a major role of non-additive gene effects in the inheritance of this trait. Duplicate epistasis between sets of three genes under both environments was recorded for the cross Raj 911 × DWL 5002. Epistatic interactions, particularly the trigenic ones, contributed the maximum significant heterosis. Epistatic interactions involving dominance in the F₂ generations caused significant inbreeding depression. Selective diallel mating and/or biparental mating could be used for amelioration of grains per spike in durum wheat.     

Two major genes for seed size in chickpea (Cicer arietinum L.)

Summary Seed size as determined by seed weight, is an important trait for trade and component of yield and adaptation in chickpea (Cicer arietinum L.). Inheritance of seed size in chickpea was studied in a cross between ICC11255, a normal seed size parent (average 120 mg seed⁻¹) and ICC 5002, a small seed size parent (average 50 mg seed⁻¹). Seed weight observations on individual plants of parents, F₁, F₂, and backcross generations, along with reciprocal cross generations revealed that the normal seed size was dominant over small seed size. No maternal effect was detected for seed size. The numbers of individuals with normal, small and medium (average 150 mg seed⁻¹) seed sizes in F ₂ population were 1237, 323 and 111 fitting well to the expected ratio of 12:3:1 (χ² = 0.923, P = 0.630). The segregation data of backcross generations also indicated that seed size in chickpea was controlled by two genes with dominance epistasis. We designate the genotype of ICC 11255 as Sd ₁ Sd ₁ sd ₂ sd ₂, and ICC 5002 as sd ₁ sd ₁Sd₂ Sd ₂ wherein Sd ₁ is epistatic to Sd ₂ and sd ₂ alleles.     

A quinclorac sensitive lethality rice mutant: its discovery,genetics and potential application

In this study, we reported a quinclorac‐sensitive rice natural mutant M4017, derived from an indica restorer line 4017 of three‐line hybrid. The mutant could be killed at three‐leaf stage by quinclorac at 175 mg/l or higher, a dosage that is recommended for monocot herbs control. The mutant at flowering stages can also be effectively killed by quinclorac at 1.25–1.50 g/l or higher, which is safe for its F₁ hybrids and all other normal varieties. Genetic analysis, using the F₁, F₂ and BC₁ populations derived from this mutant and other often‐used varieties, revealed that quinclorac sensitivity/lethality was controlled by a single recessive gene, which was named quin1. This mutant has a potential application in false hybrid seed removal or mechanized production of hybrid seeds.     

Reproductive behaviour and broomrape resistance in interspecific hybrids of sunflower

Interspecific hybrids and backcross generations between the wild perennial species Helianthus resinosus, Helianthus paucifiorus, Helianthus laevigatus, Helianthus nuttallii ssp. nuttallii T. & G. and Helianthus giganteus, resistant to broomrape (Orobanche cernua) and susceptible inbred lines were obtained to study crossability to cultivated sunflower and the transmission and expression of resistance to this parasitic weed. Conventional crosses with all the species tested were successful except for the crosses with diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F₁ hybrids with hexaploid species and lowest for those with the diploid H. giganteus. We evaluated F₁, BC₁F₁, some BC₂F₁ plants and the wild and cultivated parents. The wild species and interspecific hybrids were resistant to broomrape infection except for H. nuttallii, which showed segregation, indicating that the resistance is dominant. The crossability and resistance of F₁, and back-cross generations of species with different ploidy levels indicate that the transfer of broomrape resistance to cultivated sunflower is feasible.