摘要:

AbstractThe types of resistance to viruses in potato are immunity, extreme resistance coded for by the R genes and hypersensitivity coded for by the N genes. Immunity prevents the establishment of virus infection, whereas extreme resistance is expressed as an extremely low virus titre resulting from restricted virus multiplication or localization of virus infection in the plant without obvious necrotic reactions. Expression of the N genes can also lead to localization of the virus infection followed by necrosis at the infection site. Tolerance to virus infection and resistance to inoculation and virus vectors are useful components of field resistance. Virus or virus strain specific resistance genes have been identified in cultivated and wild potato species and transferred to cultivated potato. However, combining resistance to the three globally most important viruses PLRV, PVY and PVX has proved difficult, and new sources of broad spectrum resistance to viruses are required for potato breeding. New molecular techniques will enhance the isolation of the natural resistance genes and studies of gene regulation.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01270.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractTo study the genetic structure of open‐pollinated faba bean varieties, three sets of genotypes were generated from each of the varieties ‘Minica’, ‘Kristall’, and ‘Deiniol’: (1) inbred lines developed by single‐seed descent in bee‐proof isolation cages, (2) intravanetal and (3) intervarietal F1‐hybrids produced by controlled hand crossing. In 1989 and 1990, a total of 144 entries, including the three open‐pollinated source varieties, were grown in single‐row plots with two replications at two locations in Western Germany.Performance data of the inbred lines revealed relatively large genotypic variability within each variety, for all the characters studied, which was greater in ‘Deiniol’ and ‘Kristall’ than in ‘Minica’. An average yield heterosis of 20 %, 39 % and 57 %, respectively, was found for the intravarietal hybrids, whereas that of the intervarietal hybrids varied between 70 and 73 %. Compared to the mean yield of the inbred lines the superiority of the open‐pollinated source variety was small and not significant in ‘Minica’ (6 %), but it was large and highly significant in ‘Kristall’ (22 %) and ‘Deiniol’ (37 %).The present investigation revealed in faba bean that similar performance levels of open‐pollinated varieties may result from either highper seperformance under inbreeding with low heterosis values or from lo

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01271.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractCultivation of faba beans (Vicia fabaL.) is hampered by poor yield stability. The genetic variation at the homozygous level for yield stability in the gene pool of the small‐seeded and indeterminate European faba beans and the usefulness of auxiliary traits for the improvement of yield stability were investigated. The concept of stability, based on the regression technique, was applied. A sample of 36 faba bean lines was tested in 16 environments and a subsample of eight lines was tested in 11 additional environments. Significant differences were found between lines for yield stability parameters, but the repeatability of the results was limited. Early maturity correlated markedly (r = 0.51**) with one of the yield stability parameters (deviation from regression). Although lodging resistance was not correlated with the stability parameters, it proved to be a safety factor for performanc

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01272.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn order to evaluate the effects of heterogeneity and heterozygosity on yield stability in faba beans, genotypes were generated with contrasting population structures, differing only in their levels of heterogeneity and heterozygosity. All entries were based on either eight or 36 inbred lines, respectively. The population structures tested consisted of pure stands of the inbred lines (1) and of their F1,‐hybrids (2), blends of the inbred lines (3) and of their F1hybrids (4), four‐component synthetics in different Syngenerations (5), the open‐pollinated source varieties (6) and 36 polycross progenies (7). Five different entry sets (= data sets), each covering several of the seven population structures listed, were grown during 1986 to 1991 in at least four different environments in Western Germany and tested for yield.Stability parameters, i.e., the regression coefficient and deviation from regression (EBERHART and RUSSELL 1966), and the ecovalence (WRICKE 1962), revealed that yield stability of the different population structures was improved by increasing heterozygosity as well as heterogeneity. But the impact of both factors of diversity on yield stability varied between the different data sets. Positive effects of both factors on yield stability seemed to be additively combined in the hybrid blends (data set I). The same proved to be partly true for the four different Syn‐generations of the nine synthetics tested. Yield advantage of the different heterozygous variety structures over the homozygous ones in creased with increasing yield level at test sites, as indicated by regression coefficients larger

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01273.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractWheat breeding programmes in Albania depend upon the use of diverse genetic material of local origin and on special environmental conditions; the present study being conducted under drought stress conditions. Grain yield, yield components, plant height and test weight were estimated in an F5generation of a winter wheat population at Kamez in 1989—90 and 1990—91 and at Lushnje in 1989—90. The highest values of heritability were observed for plant height, kernel weight and spike length. Due to drought stress the heritability of kernels per spike was low. None of the correlated responses was higher than the direct response for yield. Maximum genetic gain was expected when yield, plant height, spike length, kernels/spike and kernel weight were included in the

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01274.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractTwelve fertile alloplasmic wheat lines, produced by substituting four nuclear genomes ofTriticum aestivuminto the cytoplasms ofT. timococcumKostoff,T. timopheeviZhuk., andAegilops ventricosaTausch, were examined for cytoplasmic effects on falling number and α‐amylase activity during grain development in different environments. Nuclear genome, cytoplasm and environment were important sources of variation for falling number. In one environment, where the plants were exposed to very hot, dry conditions, the levels and patterns of change in α‐amylase activity were also significantly affected by the cytoplasm. The data indicated that alien wheat cytoplasms might result in useful additional variation in specific environments where sprouting is a pr

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01275.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSugars are critical components in bread wheat (Triticum aestivumL.) anther culture media for successful somatic embryo initiation and plant regeneration. In this experiment, anthers from three wheat genotypes were cultured on a modified Liang's 85D12 initiation medium with seven sugar combinations (I‐sugars: galactose, mannose, maltose, fructose, sucrose, glucose, maltose + glucose) at 0.26M, and 2,4‐dichlorophenoxyacetic acid (2 mg/L), 1‐naphthalene acetic acid (1 mg/L), and glutamine (254 mg/L). Wheat starch (5 % W/V), a potential source of sugars, was used as the medium gelling agent. No previous research has studied the effect of different sugars with wheat starch. A split‐plot experimental design with 42 replications was used with genotypes as whole plots and sugar combinations as subplots. Galactose and mannose did not support embryoid initiation and were dropped from the analysis. Averaged over the three genotypes, maltose was the best sugar (105 embryoids/100 anthers), followed by glucose (47 embryoids/100 anthers) and maltose + glucose (37 embryoids/100 anthers). These three sugar combinations were superior to the standard medium sugar, sucrose (24 embryoids/100 anthers), and to fructose (12 embryoids/100 anthers). The embryoids were divided into two groups for plant regeneration. The first group was transferred to regeneration medium (Liang 85D12 salts, sugars at 0.06M, and wheat starch at 7 % w/v as gelling agent) with the same sugar (R‐sugar) used as in initiation. The second group was transferred to regeneration media with sucrose. I+R‐ma

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01276.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSynthetic hexaploids (SH) developed at the International Maize and Wheat Improvement Center (CIMMYT), involving fourTriticum turgidumand nineT. tauschiiparents, were evaluated for resistance to Karnal bunt (KB)(Tilletia indicaMitra) during three crop seasons over three years at Ciudad Obregon, Sonora, Mexico. Ten tillers of each SH at boot stage, taken at random, were injected with a suspension of sporidia in water (10,000 spores/ml of water). At maturity the inoculated spikes were threshed individually and evaluated for the percentage KB‐infected grains. Based on the mean KB score of each entry for three seasons, 49 % of the SH were immune (0 % infection) to KB. Highly resistant expressions characterized the SH which appeared to be influenced by the resistance of theirT. turgidumand/orT. tauschiiparents. The overall mean infection of the SH wheats was 0.24 % compared to 56.14 % in the susceptible bread wheat check cultivat ‘WL711’. Transfer of KB resistance genes from SH wheats into bread wheat is currently underway at C

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01277.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThis report gives the first detailed analysis of cucumber haploid plants and the first evaluation of genotype and season effects on haploid embryo development. Female flowers of four F1 varieties and two inbred lines were pollinated with 300 Gy‐treated pollen and three‐week old embryos were culturedin vitroon E20A medium. The variety ‘Polan’ produced the greatest number of embryos (1.34 per 100 seeds), 51 % of which were capable of further development. The number of embryos able to develop was four times higher in summer than in spring. All the plants obtained, except one, were haploids or aneuhaploids. Haploid plants grew slowly and were sterile, although they occasionally set seedless fruits. The length of the stems, leaves and guard cells was smaller than those of d

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01278.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSynthetic lines of wheat were compared in order to determine the effect of the “D” genome on embryo induction and plant regeneration from anther culture. The experiments were performed using 6 genotypes of wheat in a randomized block design with 4 replications.In all cases except one, addition of the “D” genome fromT. tauschiiincreased the efficiency of embryo formation and green plantlet production. This positive effect of the “D” genome does not exclude the existence of possible interactions between the three genomes (A, B and D) and/or the effect of each genome

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb01279.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY