The inheritance of flowering time in garden stock (Matthiola incana R.Br.)

Summary The inheritance of flowering time (FT) in a cross between early-flowering (P1) and late-flowering (P2) Matthiola incana genotypes, was investigated. The distribution of FT in F1, F2 and BC1 generations indicated an additive genetic control with partial dominance of earlines alleles, particularly with regard to double-flowered plants. Single-flowered plants flowered earlier than double-flowered plants, averaged within both parental lines; however, the mean difference between singles and doubles was 16 days for P1 as compared with 6 days for P2. This flower-doubleness related delay in FT was found to be heritable, by analysis of F3 family means. The implications of these results on the breeding of stock cultivars is discussed.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 1138-E, 1993 series.     

Allelic relationships of genes controlling number of flowers per axis in chickpea

Genetic variation for number of flowers per axis in chickpea (Cicer arietinum L.) includes single-flower, double-flower, triple-flower and multi-flower traits. A double-flowered (DF) line ICC 4929, a triple-flowered (TF) line IPC 99-18 and a multi-flowered (MF) line JGM 7 were intercrossed in all possible combinations and flowering behavior of parents, F₁s and F₂s was studied to establish allelic relationships, penetrance and expressivity of genes controlling number of flowers per axis in chickpea. The F₁ from ICC 4929 (DF) × IPC 99-18 (TF) cross were double-flowered, whereas F₁ from ICC 4929 (DF) × JGM 7 (MF) and IPC 99-18 (TF) × JGM 7 (MF) crosses were single-flowered. The F₂ from ICC 4929 (DF) × IPC 99-18 (TF) cross gave a good fit to a 3:1 ratio for double-flowered and triple-flowered plants. The F₂ from ICC 4929 (DF) × JGM 7 (MF) cross segregated in a ratio of 9:3:3:1 for single-flowered, double-flowered, multi-flowered and double-multi-flowered plants. The F₂ from IPC 99-18 (TF) × JGM 7 (MF) cross segregated in a ratio of 9:3:4 for single-flowered, triple-flowered and multi-flowered plants. The results clearly established that two loci control number of flowers per axis in chickpea. The double-flower and triple-flower traits are controlled by a single-locus (Sfl) and the allele for double-flowered trait (sfl ^d ) is dominant over the allele for triple-flower trait (sfl ^t ). The three alleles at the Sfl locus has the dominance relationship Sfl > sfl ^d > sfl ^t . The multi-flower trait is controlled by a different gene (cym). Single-flowered plants have dominant alleles at both the loci (Sfl_ Cym_). The double-flower, the triple-flower and the multi-flower traits showed complete penetrance, but variable expressivity. The expressivity was 96.3% for double-flower and 76.4% for double-pod in ICC 4929, 81.2% for triple-flower and 0.0% for triple-pod in IPC 99-18, and 51.3% for multi-flower and 24.7% for multi-pod in JGM 7. Average number of flowers per axis and average number of pods per axis were higher in JGM 7 than double-flowered line ICC 4929 and triple-flowered line IPC 99-18. The results of this study will help in development of breeding strategies for exploitation of these flowering and podding traits in chickpea improvement.     

Inheritance of cleistogamic flowering in durum wheat (Triticum durum)

Summary Generally durum wheat flowers are chasmogamous but very rarely, cleistogamy may be observed. Genetic studies based on six crosses and back crosses showed that chasmogamy was determined by a single dominant gene Cl, plants homozygous for the recessive allele, cl, were cleistogamous. The flowering behaviour phenotypes were unaffected by environmental conditions. Cleistogamy was attributed to poorly developed lodicules and stiff perianth.     

A gene producing one to nine flowers per flowering node in chickpea

Chickpea (Cicer arietinum L.) has a racemose type of inflorescence and at each axis of the raceme usually one or two and rarely three flowers are borne. Plants producing 3 to 9 flowers, arranged in acymose inflorescence, at many axis of the raceme, were identified in F₂ of an interspecific cross ICC 5783 (C. arietinum) × ICCW 9 (C. reticulatum)in which both the parents involved were single-flowered. A spontaneous mutation in one of the two parents or in the F₁was suspected. However, the possibility for establishment of a rare recombination of two interacting recessive genes could not be ruled out. The number of pods set varied from 0 to 5 in each cyme. Inheritance studies indicated that a single recessive gene, designated cym, is responsible for cymose inflorescence. The allelic relationship of cym with sfl, a gene for double-flowered trait, was studied from a cross involving multi flowered plants and the double-flowered line ICC 4929. Thecym gene was not allelic to sfl, suggesting that two loci control the number of flowers per peduncle in chickpea. The cym locus segregated independently of the locus sfl, ifc (inhibitor of flower color) and blv (bronze leave). This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterization,inheritance, and molecular study of opaque leaf mutant in mungbean (<Emphasis Type="Italic">Vigna radiata</Emphasis> (L.) Wilczek)

Chlorophyll-deficiency mutants are useful as genetic markers and as materials for studying the photosynthesis process. We characterized the inheritance of the gene controlling an opaque leaf (OL) trait in mungbean (Vigna radiata (L.) Wilczek). An F₂ population was developed from the cross between the OL mutant and ‘Berken’, an Australian mungbean cultivar, to study inheritance and molecular tagging. The population was advanced by selfing to produce F₅ lines from which two normal lines and two OL lines were randomly chosen to study chlorophyll content, seed growth and development, and seed cell morphology. The chlorophyll content in opaque leaf was lower than normal and thus was expected to have lower photosynthetic activity. This resulted in yellowish and shrinking pods and seeds within 15 days after flowering, while those from normal plants extended their growth up to 18 days. The cotyledon transfer cells of the OL plants deformed at 12 days and deteriorated at 14 days after flowering. The OL trait was controlled by a single recessive ol gene which was independent from the genes controlling petiole color and growth habit. We used 193 AFLP primer combinations to tag this gene and found that the marker AGG/ATA was linked with the ol gene at a distance of 3.4 cM.     

A study of dominance at the locus controlling cyanoglucoside production in Trifolium repens L.

Summary The Ac allele for cyanoglucoside production in white clover has been shown to be incompletely dominant and a dosage effect is indicated at this locus. The recessive allele, ac, when homozygous gives rise to absence of cyanoglucosides in the leaf tissue, whereas in heterozygous plants it has been shown to reduce the level of cyanoglucoside, to a level less than half the value found in Ac Ac plants.     

Some yield components and ideotype traits in meadowfoam,a new industrial oil crop

Summary Three populations of Limnanthes alba and five of L. douglasii were investigated for relative growth rates, leaf area index, flowering time, seed and oil yield, seed size and shattering. Within each species the early flowering populations had the highest seed yield. Most accessions developed adequate leaf canopy by the time of onset of flowering.An ideotype for breeding goals could be defined in terms of the characters of L. douglasii var. nivea such as early flowering and high seed yield, provided taller plant stature and reduced seed shattering are incorporated.Domestication and breeding might involve a combination of induced mutation, interspecific hybridization and conventional breeding procedures.     

Chloroplast-DNA variation in the wild and cultivated olives (Olea europaea L.) of Morocco

The male sterile plants that segregated in a BC₅F₂ of `C. sericeus × C. cajan var. TT-5' population were maintained by sib mating. The male sterile plants were crossed with ICPL-85012.Approximately 50% of the F₁ plants were sterile. F₂ plants derived from the fertile F₁ plants did not segregate for male sterility. The reciprocal hybrid i.e. ICPL-85012 × Fertile derivatives from C. sericeus × TT-5, did not express male sterility. However, among the 12 F₂ plant to row progenies, two segregated 25% male sterile plants and remaining 10 did not segregate. The segregation pattern in subsequent progenies revealed that the sterility was under control of a single recessive allele. Studies on the backcross and their BC₁F₂ and BC₁F₃progenies revealed another sterility gene which was found to be dominant in inheritance. This paper shows that what was thought to be cytoplasmic male sterility from C. sericeus cytoplasm is actually a single dominant gene possibly acting in concert with a single recessive gene to mimic cytoplasmic male sterility. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mapping of Re,a gene conferring the red leaf trait in ornamental kale (Brassica oleracea L. var. acephala)

Variegated leaf colour is an important agronomic trait that affects the market value of ornamental kale (Brassica oleracea L. var. acephala). The red leaf phenotype in kale is due to anthocyanin accumulation. To investigate the pattern of inheritance of this trait, we constructed an F₂ population by crossing ‘Y005‐15’, a double haploid with red leaves, with a white‐leaved double haploid, ‘Y011‐13‐38’, followed by self‐pollination. An F₂ population consisting of 4284 individuals was used to study the inheritance of this trait, which showed that the character was controlled by a dominate gene. All of the 1050 white leaf trait plants in the F₂ were used for mapping and developing markers linked to Re gene. Results showed that Re was mapped to a locus on linkage group C09 of Brassica oleracea, and the locus was mapped between six SSR markers (C9Z1, C9Z16‐1, C9Z90, C9Z94, C9Z96 and C9Z99), with a genetic distance of 6.7, 1.0, 0.3, 2.0, 2.1 and 0.4 cM from Re gene, respectively. These results may facilitate marker‐assisted selection of the red leaf trait in kale breeding as well as map‐based cloning of the red leaf trait gene.     

Inheritance of resistance to angular leaf spot (Isariopsis griseola Sacc.) in french bean (Phaseolus vulgaris L.)

Summary Angular leaf spot (Isariopsis griseola Sacc.) is a serious disease of French bean in the hills of India and 40 to 70 per cent of the green pods are damaged and rendered unmarketable. Crosses were made between PLB 257, (Phaseolus coccineus L.), a red flowering pole tope, resistant to angular leaf spot, and Contender (Phaseolus vulgaris L.), a highly susceptible commercial cultivar. Studies of the F₁, F₂, and F₃ progenies indicated that PLB 257, carries a recessive gene imparting resistance to angular leaf spot.     

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.     

A partially male-sterile mutant line of soybeans,Glycine max (L.) Merr.: inheritance

Summary A partial male sterility system in the soybean (Glycine max (L.) Merr.) germplasm population AP6(SI)CI was found to be controlled monogenically by a recessive allele, msp. Observations of msp msp plants in different environments suggested that environmental conditions significantly affect expressivity of the msp allele with respect to male sterility. We obtained no experimental evidence of cytoplasmic effects on msp expression. Background genotypes, however, seem to affect msp expressivity through their determination of flowering dates and resultant interactions with varying environmental conditions.Homogeneous populations of partially male-sterile plants can be generated by increasing families of msp msp plants in fertility-inducing environments, if measures are implemented to prevent the introduction and/or build-up of fertile genotypes that arise from natural cross-pollinations.Joint contribution: North Central Region, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, and Journal Paper No. J-9596 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011; Project 2107.     

Identification of segregation-distortion-neutral alleles to improve pollen fertility of indica-japonica hybrids in rice (Oryza sativa L.)

The genetics of resistance to Ascochyta blight (Ascochyta fabae f. sp. fabae) was studied in two populations of faba bean (Vicia faba). Plants of a resistant population, ILB 752, and a susceptible one, NEB 463, were screened for their reaction to the pathogen and the results were quantified on a scale of 0–5. Crosses were made between plants both within and between accessions and the F₁ and F₂ generations assessed in a field trial 21 and 45 days after inoculation. Disease scores were greater at 45 days than at 21 days and they were not significantly affected by the presence of susceptible spreader rows in part of the trial. ILB 752 carried a major dominant gene conferring resistance while NEB 463 carried the recessive allele for susceptibility. Furthermore, a minority of plants of NEB 463 appeared to carry at least one pair of complementary recessive genes, also conferring resistance. Most of the plants of ILB 752 were homozygous for the dominant resistance gene and a few were heterozygous. Reciprocal crosses behaved identically, indicating the absence of maternal effects in the expression of Ascochyta blight resistance in faba beans. The results show that it is important to confirm the level of heterozygosity for the resistance genes in this partially outbreeding species before crossing is commenced. The major dominant gene for resistance, identified in ILB 752, has clear potential for use in breeding for Ascochyta blight resistance. The minor genes identified in NEB 463 also show the potential for accumulating resistance through mass selection. This revised version was published online in July 2006 with corrections to the Cover Date.     

Tree and fruit traits of progenies from the cross between (Annona cherimola Mill.?×?A. squamosa L.)?×?A. reticulata L. and approaches for the introgression of valuable genes from A. reticulata L.

Atemoya (Annona cherimola Mill. × A. squamosa L) and A. reticulata L. possess several contrasting foliage characteristics. Two hundred and fifty trispecies hybrids of atemoya and A. reticulata were therefore studied to investigate the inheritance of four foliage characteristics. Segregation for leaf colour (green or dark green), leaf angle (erect or drooping), leaf apex shape (rounded or pointed) and time of leaf fall (early or late or intermediate) into discreet phenotypic classes revealed that their inheritance followed simple Mendelian genetics. Based on phenotypes of parents and the segregating population, and the genetic ratios obtained, allelic symbols were assigned to four leaf characteristics. Duplicate dominant gene interaction governed the leaf colour and leaf position. Thus individuals with single or both the dominant genes (A-B-, A-bb, aaB-) produce green colour leaves and those with recessive genes (aabb) dark colour leaves. Likewise erect leaf individuals are C-D-, C-dd, ccD- and those with drooping leaves are ccdd. Further a single gene determined shape of leaf apex that was either rounded (Rr) or pointed (rr). Segregation of progenies for leaf fall into early (J ^E J ^E ), intermediate (J ^E J ^L ) and late (J ^L J ^L ) suggested that codominant alleles were responsible for time of leaf fall. The inheritance studies reported in this paper should guide in Annonaceous fruit breeding for foliage characteristics or could be used as selection criteria for those important traits with which they are associated.     

Inheritance of foliar zingiberene contents and their relationship to trichome densities and whitefly resistance in tomatoes

The sesquiterpene zingiberene, present in leaf glandular trichomes, is reportedly responsible for the high level of arthropod resistance found in Lycopersicon hirsutum var. hirsutum. This paper reports on the inheritance of zingiberene contents and of the various types of glandular trichomes in the interspecific cross L. esculentum × Lycopersicon hirsutum var. hirsutum. Plants of L. esculentum ‘TOM-556’ (= P₁), L. hirsutum var. hirsutum ‘PI-127826’(= P₂), F₁ (P₁ × P₂) and F₂ (P₁ ×P₂) were evaluated for zingiberene contents and densitities of and glandular (types I, IV, VI and VII) trichomes. Broad sense heritabilities were high for all traits studied (0.678, 0.831, 0.996, 0.799 and 0.717 respectively for zingiberene and trichome types I, IV, VI, VII). There were significant positive genetic correlations between zingiberene contents and densities of trichomes types IV, VI and VII. Inheritance of zingiberenecontents can be explained mostly by the action of a single major locus, inwhich the allele from L. hirsutum that conditions high content is incompletely recessive over the allele from L. esculentum. Action of an incompleteley recessive allele in one major locus appears to be evident for densities of trichome types IV, VI and VII, but there is also evidence of the action of other epistatic loci for types IV and VI. F₂ genotypes selected for high zingiberene levels showed higher levels of resistance to the silverleaf whitefly Bemisia argentifolii than L. esculentum ‘TOM-556’, levels that were comparable those found in L. hirsutum var. hirsutum ‘PI-127826’ and other whitefly resistant accessions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Male-sterility in the grain amaranth (Amaranthus hypochondriacus ex-Nepal) variety Jumla

Summary Twenty naturally occurring male-sterile plants were recovered from a normal population of the grain amaranth, variety Jumla. The identification of the male-sterile plants is possible during anthesis and after flowering. The male-sterility in this variety is conditioned by a single recessive nuclear gene ms.This research was supported by Grant No. AMA-KE-4-83-22 (CRG GRANT) from the National Academy of Science, USA. Reprint requests to V.K. Gupta.     

Variability and inheritance of flowering time and duration in Actinidia chinensis (kiwifruit)

We investigated the variability and inheritance of flowering in a seedling population of diploid Actinidia chinensis Planch. We found considerable variation in time to reach 50% flowering (D50) and flowering duration (FD). D50 was highly heritable (h ² > 0.85) suggesting that this trait would respond well to selection in this population, whereas FD was greatly affected by the environment (h ² < 0.20). The results also showed that the flowering times of male vines were more sensitive to the environment than those of female vines. However, significant specific combining ability (SCA) effects could be achieved by targeting specific bi-parental combinations for breeding and selection of flowering time. The diversity in flowering traits among males will facilitate the selection of male pollinizers that coincide in flowering time with present or future female cultivars. The possibility of breeding female cultivars with a short flowering period to improve the consistency of fruit maturity at harvest is discussed.     

Endopeptidase polymorphism and linkage of the Ep-D1c null allele with the Lrl9 leaf-rust-resistance gene in hexaploid wheat

The aim of this study was to test whether the null allele Ep-D1c of the endopeptidase Ep-D1 can be used as a marker for the Lrl9 leaf rust resistance gene. The frequency of Ep-D1c was determined in 1134 winter wheat, spring wheat and spelt breeding lines and varieties. Only eight lines were found to carry Ep-D1c. Six of these lines originated from crosses with RL6040, the gene donor for Lrl9. The other two lines were leaf-rust susceptible in the seedling stage and therefore did not carry Lr19. The genetic distance between Ep-D1c and Lr19 was determined in a reciprocal cross between the lines FAP75184 (Ep-D1c, Lr19) and FAP75106 (Ep-D1a, leaf-rust susceptible in the seedling stage). Out of 840 F₂ seedlings screened, 162 were homozygous for Ep-D1c. From 150 of these F₂ plants, F₃ seedlings were screened for segregation for leaf-rust resistance with isolates avirulent on Lr19. Only one F₂ plant produced susceptible F₃ progeny indicating a recombination event between Ep-D1c and Lr19. From these data, a genetic distance of 0.33 ± 0.33cM between Ep-D1c and Lr19 was calculated. The results show that Ep-D1c is a useful marker for a practical breeding programme allowing the rapid identification of plants homozygous for Lrl9.     

The V f gene for scab resistance in apple is linked to sub-lethal genes

Summary V _f is the most widely used resistance gene in the breeding for scab resistant apple cultivars. Distorted segregation ratios for V _f -resistance have frequently been reported. Here we revealed that sub-lethal genes caused the distorted segregation. The inheritance of V _f was examined in six progenies by testing linked molecular markers. Three progenies showed distorted segregations that could be explained by three sub-lethal genes (sl1, sl2 and sl3), of which sl1, sl2 were closely linked to V _f . The s11 gene was located at about 14 cM from V _f and expressed itself only in the presence of another independently segregating sub-lethal gene sl3. Only the double homozygous recessive genotypes (sl1sl1 sl3sl3) were lethal, which occurred at first as dwarf and poor vigour plants during the first three months after germination. The sl2 gene was also linked to V _f and its lethality was expressed prior to seed germination and also required the homozygous recessive presence of sl3. The map position of sl3 has not yet been identified. The linkage of V _f to sub-lethal genes usually results in a shortage of V _f -resistant progenies. But in some exceptional crosses, it will lead to abundance of resistant seedling.An erratum to this article can be found at     

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.