Development of co-dominant amplified polymorphic sequence markers for resistance of sunflower to downy mildew race 730

The inheritance of the reaction of sunflower to downy mildew was investigated using resistant and susceptible near isogenic lines (NILs) and their F₃ families. Resistance to race 730 was evaluated using the whole seedling inoculation technique. Seventy-three F₃ families were inoculated, among which 54 families were resistant and 19 susceptible, fitting a 3 : 1 segregation ratio. F₃ families were also studied using several PCR markers. Ten markers at the Pl6 locus, specific for the resistant line, also segregated in F₃ families with a 3 : 1 ratio. The same segregation ratio occurred for microsatellite haplotypes that resembled the resistant parent, and were amplified with ORS 166 and ORS 1043. The only common fragment that was observed between resistant and susceptible parental lines was one of the TIR-NBS-LRR resistance gene analogue markers, having a restriction site. Two co-dominant cleaved amplified polymorphic sequence (CAPS) markers were obtained. The mapping data indicate that several dominant markers and two CAPS markers, developed here, completely co-segregate with the Pl6 gene conferring resistance to race 730. CAPS markers will facilitate efficient marker-assisted selection for sunflower resistance to downy mildew race 730.     

Inheritance and gene tagging of male fertility restoration of cytoplasmic-nuclear male-sterile line NJCMS1A in soybean

The F₁, F₂ and F_2:3 of the NJCMS1A × 'Zhongdou 5' cross were used to analyse the inheritance of the male fertility restoration of the cytoplasmic-nuclear male-sterile line NJCMS1A in soybean. The results of genetic analysis showed two pairs of dominant genes conferring the male fertility restoration of NJCMS1A, which further confirmed previous results. The F₂ population from the NJCMS1A × 'Zhongdou 5' cross was used for tagging the restorer genes for NJCMS1A with 664 pairs of simple sequence repeat primers selected randomly from the genetic linkage map of soybean published by Cregan et al. (1999) . Satt626 on linkage group M and Satt300 on linkage group A1 of the integrated linkage map by Song et al. (2004) were found to link to the two restorer genes of NJCMS1A. The maximum-likelihood estimates of the genetic distance between the two markers, Satt626 and Satt300, and the two restorer genes of 'Zhongdou 5' were 9.75 and 11.18 cM, respectively.     

Identification and molecular tagging of a stripe rust resistance gene in wheat line P81

Stripe rust, caused by Puccinia striiformis f. sp. tritici (PST), is one of the most devastating diseases in common wheat ( Triticum aestivum L.). With the objective of identifying and tagging a new gene for resistance to stripe rust in wheat line P81, F₁, F₂ and F_2:3 populations from the cross 'Chuanmai 28'/P81 were inoculated with Chinese PST race CYR32 in greenhouse and field trials. P81 carried a single dominant gene for resistance (designated YrP81 ) to CYR32. Tests of allelism showed that YrP81 was different from Yr5 , Yr10 , Yr15 and Yr26 . Simple sequence repeat (SSR) and resistance gene-analogue polymorphism (RGAP) between the parents were used for genotyping the F₂ populations. YrP81 was closely linked to four SSR loci on chromosome 2BS with genetic distances of 18.3 cM ( Xwmc25 ), 1.8 cM ( Xgwm429 ), 4.1 cM ( Xwmc770 ) and 5.3 cM ( Xgwm148 ). Two RGAP markers RGA1 (NLRR/XLRR) and RGA2 (Pto kin4/NLRR-INV2) were also closely linked to YrP81 with genetic distances of 4.7 and 6.3 cM, respectively. The linkage map of YrP81 and molecular markers was established in the order Xwmc25 - RGA2 - RGA1 - Xgwm429 - YrP81 - Xwmc770 - Xgwm148 . Pedigree analysis, response patterns with Chinese PST races and associations with markers suggested that YrP81 is a novel stripe rust resistance gene. The PCR-based microsatellite and RGAP markers identified here could be applied in selection of YrP81 in wheat breeding.     

Uniparental inheritance of purple leaf and the associated resistance to leafminer in castor bean

Leafminer ( Liriomyza trifolii Burgess), Diptera Agromyzidae, is one of the insect pests that causes economic damage to castor bean ( Ricinus communis L.) foliage. Green leaf type is a common phenotype in castor bean and highly susceptible to leafminer. The rare purple leaf type germplasm accessions showed stable resistance to leafminer. Studies were carried out to understand the inheritance of purple leaf and the associated leafminer resistance. Direct and reciprocal crosses were made between a purple leaf parent RG1930 and a green leaf parent RG2788. RG1930 is resistant to leafminer while RG2788 is susceptible. Reciprocal differences were noted in segregation pattern of purple leaf colour as well as resistance to leafminer. Purple leaf phenotype was obtained only in purple × green (RG1930 × RG2788) cross where the female parent was a purple leaf phenotype. The reciprocal cross green × purple (RG2788 × RG1930) produced only the green leaf phenotype. Uniparental inheritance was observed for purple leaf phenotype and resistance to leafminer in F₁, F₂, F₃ and backcross generations. Progenies with a dark purple leaf were resistant to leafminer while those with a green leaf were susceptible. Visual association between a purple leaf and resistance to leafminer and their uniparental inheritance were clearly established. The role of heritable epigenetic effects are discussed in expression of purple pigment in offspring.     

Inheritance of time of flowering in upland cotton under natural conditions

Time to flowering is an essential component of the adaptation and productivity of cotton ( Gossipium hirsutum ) in various agro-ecological zones. This article presents a study of the genetic control of this trait in two crosses obtained from different early-maturity parental lines. In each cross, multiple generations including P₁, F₁, P₂, B₁, B₂ and F₂ were evaluated under two natural field conditions in 2004 and 2005. The data on time to flowering in the F₂ populations had a continuous distribution but deviated from normality. A joint segregation analysis (JSA) revealed that time of flowering in upland cotton was controlled by a mixture of an additive major gene and additive-dominant polygenes. The first- and second-order genetic parameters were all calculated based on the mixture of major gene and polygene inheritance models using JSA. These results suggested that there was considerable genetic diversity and complexity in days to anthesis in upland cotton. This variation can be used to formulate the most efficient breeding strategy and to design cotton for a particular environment.     

Cytogenetic analysis of F1, F2 and BC1 plants from intergeneric sexual hybridization between Sinapis alba and Brassica oleracea by genomic in situ hybridization

By intergeneric sexual hybridization between Sinapis alba and Brassica oleracea , F₁, F₂ and BC₁ progeny plants were produced. S. alba plants (genome SS, 2n = 24) were pollinated with B. oleracea (genome CC, 2n = 18), and the fertile F₁ plants were pollinated with B. oleracea to obtain BC₁ plants. GISH analysis showed that 10 out of 12 F₁ plants had 12 S. alba chromosomes (one full S chromosome set) and nine B. oleracea chromosomes (one C chromosome sets), representing the expected hybrids. However, two F₁ plants had 12 S chromosomes and 18 C chromosomes (two C chromosome sets), indicating unexpected hybrids. A maximum of three trivalents between C and S chromosomes were identified at metaphase I of semi-fertile F₁ pollen mother cells (PMCs), which indicates homology and chromosome pairing between these two genomes. The C genome had obviously been doubled in two F₂ plants from selfed semi-fertile F₁ plants. BC₁ plants consisted of 18 C chromosomes and different numbers of one, five and six additional S chromosomes, respectively. Monosomic alien addition lines developed in the present study can be used for B. oleracea breeding and Sinapis alba gene mapping.     

Identification of AFLP and RAPD markers linked to anthracnose resistance in grapes and their conversion to SCAR markers

Resistance to anthracnose or black spot ( Elsinoe ampelina ), a serious fungal pathogen in viticulture and table grape production, was investigated on 25 grape cultivars. Bioassays performed with culture filtrates produced by the pathogen revealed 14 resistant genotypes. In most plants resistance originated from Vitis labrucsa but also genotypes with V. rupestris and V. riparia  ×  V. rupestris background showed resistance. Genetic analysis was conducted in F₁, S₁ and BC₁ plants developed from various cultivars. In total, 326 F₁ plants were evaluated, 172 genotypes proofed to be resistant, whereas 154 were susceptible to anthracnose. A Mendelian segregation ratio of 1 : 1 (χ² = 0.30–0.65) indicating that anthracnose resistance is controlled by a single dominant gene. To facilitate the use of marker-assisted selection in grape-breeding PCR-based markers were developed by random amplified polymorphic DNA and amplified fragment length polymorphism in bulk segregant analysis. Finally, OPB 15₁₂₄₇ was developed as a sequence characterized amplified region marker being diagnostic for the locus of resistance to anthracnose in all resistant genotypes tested. Within the 25 grape cultivars OPB 15₁₂₄₇ is diagnostic in the genetic background of both V. labrucsa and V. rupestris and V. riparia  ×  V. rupestris .     

Diallel analysis of sugar composition of 10 vegetable soybean lines

Few studies have evaluated vegetable soybean for sugar content at the green pod stage. Information on combining ability and type of gene action that governs inheritance of seed traits can help breeders to select suitable parents and devise an appropriate breeding strategy. Ten vegetable soybean accessions were crossed in a complete diallel mating design. Parent lines and F₂ and F₃ progenies were evaluated for two nutritional components. In this study, both general and specific combining ability and reciprocal effects were significant for sucrose and total sugar. Cultivars 'Kanrich', 'Pella', 'Verde' and V81-1603 had good general combining ability for high sucrose. In general, high sucrose content was observed in progeny of the early maturity group genotypes 'Kanrich', 'Pella' and 'Verde'. The best combiners for high total sugar content were 'Verde', V81-1603 and PI 399055. These genotypes could serve as genetic sources in a vegetable soybean breeding programme.     

Development and agronomic performance of common bean lines simultaneously resistant to anthracnose, angular leaf spot and rust

The common bean is affected by several pathogens that can cause severe yield losses. Here we report the introgression of resistance genes to anthracnose, angular leaf spot and rust in the 'carioca-type' bean cultivar 'Rudá'. Initially, four backcross (BC) lines were obtained using 'TO', 'AB 136', 'Ouro Negro' and 'AND 277' as donor parents. Molecular fingerprinting was used to select the lines genetically closer to the recurrent parent. The relative genetic distances between 'Rudá' and the BC lines varied between 0.0% and 1.99%. The BC lines were intercrossed and molecular markers linked to the resistance genes were used to identify the plants containing the genes of interest. These plants were selfed to obtain the F₂, F₃ and F₄ plants which were selected based on the presence of the molecular markers mentioned and resistance was confirmed in the F₄ generation by inoculation. Four F_4:7 pyramid lines with all the resistance genes showed resistance spectra equivalent to those of their respective donor parents. Yield tests showed that these lines are as productive as the best 'carioca-type' cultivars.     

A CAPS marker TAO1902 diagnostic for the I-2 gene conferring resistance to Fusarium oxysporum f. sp. lycopersici race 2 in tomato

Fusarium oxysporum f. sp. lycopersici inhabits most tomato-growing regions worldwide, causing tomato production yield losses. A molecular marker linked to resistance would be useful for tomato improvement programmes. Thus, a cleaved amplified polymorphic sequence (CAPS) marker TAO1₉₀₂ was developed to identify tomato genotypes possessing the I-2 gene, which confers resistance to F. o. lycopersici race 2. The Rsa I or Fok I restriction fragments corresponded to the presence or absence of the I-2 allele in a segregating 100 F₂ progeny, tomato cultivars, 16 resistant and 20 susceptible to Fusarium wilt, respectively, lines and F₁ hybrids, representing various tomato gene pools. TAO1₉₀₂ may be helpful for selection of F. o. lycopersici -resistant tomato germplasm.     

Inheritance of a weeping character and the low frequency of rooting from cuttings of the mulberry variety 'Shidareguwa'

A mulberry variety, Morus alba 'Shidareguwa', has a weeping habit and is used as an ornamental and landscape plant. This variety is known for being difficult to propagate by hardwood cuttings. To clarify the mode of inheritance of the weeping character and its relationship to the difficulty in cutting propagation, we crossed 'Shidareguwa' with a non-weeping variety 'Noi' that has a very high rooting ability. The phenotypic segregations exhibited by the F₁ and F₂ plants suggested that the weeping habit is controlled by a single recessive gene. In tests of the F₂ plants for cutting propagation, no obvious correlation was recognized between the weeping trait and the rooting ability of cuttings. As a result, we were able to develop new weeping mulberry strains with improved high rooting ability.     

Relationships between seed oil content and fatty acid composition in high stearic acid sunflower

The high stearic acid sunflower mutant CAS-3 is characterized by a low seed oil content, which might represent a constraint for the commercial production of high stearic acid sunflower oil. The objective of the present research was to investigate the relationships between fatty acid profile and seed oil content in CAS-3. Plants of CAS-3 were reciprocally crossed with plants of breeding line ADV-37, with high oil content and standard fatty acid profile. Oil content and fatty acid composition were measured in individual F₂ seeds and F₂ plants (F₃ seeds averaged). Both F₂ seeds and F₂ plants from the cross ADV-37 × CAS-3 had a significantly higher oil content than those from the reciprocal cross, which indicated the existence of cytoplasmic effects in the genetic control of the trait. A consistent negative correlation between oil content and palmitic acid and a positive correlation between oil content and oleic acid were detected both in F₂ seeds and F₂ plants. Conversely, no consistent correlation between oil content and stearic acid was observed, which suggested the feasibility of simultaneous selection for both traits.     

Relationship of Root and Shoot Characters in Parent, F1 and F2 Populations of Rice

The direct and indirect contributions of root characters — root length, roots/plant, fresh and dry root weight on grain yield/plant were worked out from a 7 × 7 diallel set of rice hybrids. The materials were grown in pots with four replications. Path analysis was done at genotypic level of correlation.
The grain yield/plant showed positive correlation with all the root characters in parent, F₁ and F₂ except with roots/plant in F₁ population. Fresh root weight demonstrated positive direct effect on grain yield/plant in all the three generations. Roots/plant had highly positive direct effect in F₂. Direct effects were negative in respect of root length and dry root weight in F₂ generation.     

Hybridization of Thinopyrum distichum and Secale cereale

An attempt was made to determine whether the salt tolerance genes of Thinopyrum distichum would be expressed in the presence of the rye genomes and if it would be possible to improve and utilize its hybrid with rye as a salt-tolerant fodder crop. Th. distichum florets were pollinated with diploid and tetraploid rye but hybrids were obtained only with tetraploid rye. The F₁ had 28 chromosomes and expressed high levels of salt tolerance. Fertility could not be induced through colchicines treatment but the plants produced some apomictic seeds during the summer months. The F₂ had 20-22 chromosomes and retained two complete or near-complete rye genomes. The F₂ plants responded better to colchicine treatment, however, the doubled hybrids remained male sterile. In summer, one F2 plant produced many apomictic seeds with chromosome numbers ranging from 14 to 16 (primarily rye chromosomes). The mechanism that caused the preferential loss of Thinopyrum chromosomes in each apomictic cycle remains unknown. The F₃ phenotypically resembled rye, had primarily reductional male meioses and produced seemingly functional pollen, but were self-sterile.     

Inheritance of very high glucosinolate content in Ethiopian mustard seeds

Seed meal amendments rich in glucosinolates are of interest for soil pest and disease control. The Ethiopian mustard ( Brassica carinata A. Braun) line N2-6215, with very high levels of seed glucosinolates (160 μmol/g), was developed from the line C-101 (116 μmol / g) following mutagenesis. The objective of this research was to study the inheritance of very high seed glucosinolate content. Plants of N2-6215 were reciprocally crossed with plants of the line C-101. The F₁, F₂, and BC₁F₁ plant generations were evaluated in two environments and seeds from individual plants were analysed for total glucosinolate content. The very high glucosinolate content in N2-6215 seeds was largely subject to maternal control. No cytoplasmic effects were detected. The trait was found to be oligogenic and determined by at least two or three genes. The estimates of broad-sense heritability were 0.45 and 0.58 in both environments, whereas the estimates of narrow-sense heritability were 0.35 and 0.50. The moderate heritability and oligogenic control of the trait suggest the feasibility of breeding for increased seed glucosinolate content in Ethiopian mustard.     

Nitrogen Fixation, Growth and Yield of Intercropped Mungbean (yigna radiata L.) and Groundnut (Aracbis bypogaea L.) as Affected by the Genotype

¹⁵N-aided investigations were conducted to ascertain the Nj fixation and the nitrogen (N) contribution by mungbean ( Vigna radiata L.) and groundnut ( Aracbis hypogaea L.) when intercropped with maize ( Zea mays ). The study involved growing seven genotypes of the above legumes with maize in alternate rows in two separate experiments. A sole crop of maize was used as the reference crop to determine N2 fixation by the ¹⁵N methodology. Significant genotypic differences in pod yield and stover N content were observed in intercropped mungbean and groundnut. The percentage N derived from the atmosphere showed a genotypic variation of 31 to 45 % (7 to 10 kg N₂ fixed ha⁻¹O in mungbean and 47 to 69 % (9 to 18 kg N₂ fixed ha⁻¹) in groundnut. Harvest index for N varied from 58 to 77 % in mungbean and 55 to 75 % in groundnut. In groundnut, the uptake of soil N was significantly affected by the genotype. Assuming that the N contribution to the soil by the helow-ground plant parts was negligible, the removal of seeds at maturity resulted in a negative N balance in the soil in all the genotypes of mungbean. In groundnut, some genotypes produced a positive N balance in the soil. Owing to high N₂ fixation capacity and low harvest index for N, groundnut showed a greater N supplementing ability than mungbean.     

Evaluation of the Heterosis on Leaf Photosynthesis of Remote-Cross F1 Rice (Oryza saliva L.)

The heterosis of leaf photosynthesis was studied on the main characters included in the range from CO₂exchange rate (CER) to enzymatic activity using a remote cross F, rice. The CER was significantly higher than those of the parental strains, showing a 111 % heterosis effect on average; at the same time strong heterosis was observed for the leaf area production and growth. Also stomatal and mesophyll conductances increased in the F₁ rice, which may contribute to the increase in CER. Chlorophyll content (Ch1), soluble protein content (SPC) and ribulose 1,5-bisphosphate (RuBP) carboxylase activity (RCA) were measured as the internal factors related to photosynthesis, and compared between the F₁, rice and the parents. For all these factors, the F₁ rice showed low values compared to the parents. Positive heterosis was not expressed here. On the other hand, the specific activity of RCA (RCA/SPC) increased in the F₁, rice, showing a 120% heterosis effect. This may be regarded as one of the main causes for the increase in CER of the F₁, rice. High CER expressed as heterosis concurrently with large leaf area production is one of the important findings in our study, and this may suggest a high possibility of further improvement in biomass production or yield of rice by gathering the advantageous elements into a hybrid plant.     

Pea weevil, Bruchus pisorum L. (Coleoptera: Bruchidae), resistance in Pisum sativum×Pisum fulvum interspecific crosses

The pea weevil, Bruchus pisorum (L.), is one of the most intractable pest problems of cultivated pea, Pisum sativum L., in the world. This study investigated the transfer of pea weevil resistance from two accessions (PI 595946, PI 343955) of wild pea, Pisum fulvum Sibth. & Sm., to interspecific populations derived from crossing these accessions with a weevil-susceptible pea cultivar ('Alaska 81'). Partial life tables characterized weevil stage-specific mortality and survivorship on parents and interspecific progeny in two glasshouse trials. Larval mortality rates on pods (F₃ plants) of several F_2:3 families were between 36.0% and 52.9%. These means were statistically similar to mean mortality rates on pods of resistant parents (45.4% and 46.2%), but significantly greater than mean rates on the susceptible parent (1.2% and 10.6%). Pod surface characteristics contributed to high neonate larval mortality on pods of resistant parents and interspecific progeny. Seed resistance was not broadly transferred to interspecific progeny [revealed by high weevil survivorship in seeds (means mostly >80%) and high seed damage ratings of 3–5 where ratings of 1–2 denote resistance (production of resistant seed averaged 4.2% to 22.8%)]. Estimates of total weevil mortality on pods and seeds of eight F_2:3 families were 50–70%. Thus, weevil resistance in the Pisum secondary gene pool can be transferred to interspecific progeny, thereby providing a potential avenue to develop weevil-resistant pea cultivars.     

Vererbung des β-Glucangehaltes der Haferkaryopse

Inheritance process for β-glucan content in oat caryopsis
Due to the fact that there are only few studies concerning β-glucans in oat caryopsis with regard to plant-breeding aspects, three oat crosses were performed (cross 19 = low × high, cross 86 = low × low, cross 98 = high × high). In all of the three oat crosses, lower β-glucan content (% DM) was recorded in F, than in F, indicating that the β-glucan content (% DM) at a higher heterozygoty grade is lower than at a reduced heterozygoty grade. This points to a dominant inheritance of lower β-glucan content (% DM). A tendency towards the female β-glucan content (% DM) could not be proven. Thus, it can be started from a nuclear genetic inheritance of the β-glucan content (% DM). In most cases, the experiments showed a normal distribution of β-glucan content (% DM), indicating for several genes a quantitative inheritance of β-glucan content (% DM). By means of the regression of the F₃-lines to the F₂-plants, the narrow-sense heritability could be calculated for the cross 86 (h²= 0.51***) and the cross 98 (h²= 0.48***). The heritability for the cross 19 was not significant.     

Production of intergeneric hybrids between Raphanm and Moricandia

Intergeneric F₁ hybrids between Raphanus sativus (2n = 18, RR) and Moricandia arvensis (2n = 28, MaMa) have been produced through ovary culture followed by embryo culture, when M. arvensis was used as a pistillate parent. Six BC₁ plants were also obtained through ovary culture followed by embryo culture in the backcross of an amphidiploid F₁, hybrid with R. sativus cv. 'Pink ball'. Two BC₁ plants were ses-quidiploids (2n = 32, MaRR), and the other BC₁, plants were hyperploid with 2n = 55, having MaMaRRR genomes. BC₂, seeds were obtained by conventional pollination in the successive backcross of two sesquidiploid BC₁, plants with R. sativus cv. 'Pink ball'. Their seed set percentages were 12.7% and 17.0%, respectively. These novel hybrid plants and derived progenies may be valuable materials for the genetic investigation and breeding of Brassiceae , including R. sativus.