Two chromosome segments confer multiple potyvirus resistance in maize     

T. Lübberstedt    C. Ingvardsen    A. E. Melchinger    Y. Xing    R. Salomon    M. G. Redinbaugh 《Plant Breeding》2006,125(4):352-356

Potyviruses cause serious yield losses in maize production worldwide. While the maize dwarf mosaic virus (MDMV) predominates in the USA, sugarcane mosaic virus (SCMV) is a major pathogen in China and Germany. In previous studies, inbred FAP1360A revealed complete resistance against both MDMV and SCMV. Two major SCMV resistance genes, Scmv1 and Scmv2, were located on chromosomes 6 and 3, respectively, in populations derived from crosses with the susceptible inbred line F7. For validation of these results obtained in segregating backcross‐ or F_2:3‐populations, near‐isogenic lines to F7 have been produced after one initial cross to FAP1360A by repeated backcrossing to F7, phenotypic selection for SCMV resistance, and marker‐assisted selection for the Scmv1 and Scmv2 regions from FAP1360A. The near‐isogenic line F7R has been studied in detail both at the genomic level and for resistance to different potyviruses. Based on 112 polymorphic simple sequence repeat markers, F7R received genomic segments introgressed from FAP1360A exclusively in the Scmv1 and Scmv2 chromosomal regions. F7R conferred complete resistance to SCMV and MDMV, but also to zea mosaic virus and to systemic infection by wheat streak mosaic virus. FAP1360A, F7, F7R were not systemically infected by high plains virus. Thus, introgression of Scmv1 and Scmv2 from FAP1360A into F7 was sufficient to generate the first potyvirus multiresistant European Flint line reported so far.  相似文献   

Pyramiding of Xa7 and Xa21 for the improvement of disease resistance to bacterial blight in hybrid rice   总被引：3，自引：0，他引：3  

J. Zhang    X. Li    G. Jiang    Y. Xu    Y. He 《Plant Breeding》2006,125(6):600-605

‘Minghui 63’ is a restorer line widely used in hybrid rice production in China for the last two decades. This line and its derived hybrids, including ‘Shanyou 63’, are susceptible to bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo). To improve the bacterial blight resistance of hybrid rice, two resistance genes Xa21 and Xa7, have been introgressed into ‘Minghui 63’ by marker‐assisted selection and conventional backcrossing, respectively. The single resistance gene‐introgressed lines, Minghui 63 (Xa21) and Minghui 63 (Xa7) had higher levels of resistance to bacterial blight than their derived hybrids, Shanyou 63 (Xa21) or Shanyou 63 (Xa7). Both Xa21 and Xa7 showed incomplete dominance in the heterozygous background of rice hybrids by infection with GX325 and KS‐1‐21. The improved restorer lines, with the homozygous genotypes, Xa21Xa21 or Xa7Xa7, were more resistant than their hybrids with the heterozygous genotypes Xa21xa21 or Xa7xa7. To further enhance the bacterial blight resistance of ‘Minghui 63’ and its hybrids, Xa21 and Xa7 were pyramided into the same background using molecular marker‐aided selection. The restorer lines developed with the resistance genes Xa21 and Xa7, and their derived hybrids were evaluated for resistance after inoculation with 10 isolates of pathogens from China, Japan and the Philippines, and showed a higher level of resistance to BB than the restorer lines and derived hybrids having only one of the resistance genes. The pyramided double resistance lines and their derived hybrids have the same high level of resistance to BB. These results clearly indicate that pyramiding of dominant genes is a useful approach for improving BB resistance in hybrid rice.  相似文献   

Genomic constitutions and flower characteristics of selected Aranda orchid cultivars     

Y. H. Lee 《Euphytica》1991,54(3):251-254

Summary Ten Aranda cultivars commercially grown in Singapore were selected to study their genomic constitutions and flower characteristics. Cytological evidence and breeding records of these cultivars showed that they are of three genomic classes. Four of them are diploid with AV genomes (one Arachnis and one Vanda genome), another four are triploid with AVV genomes and the remaining two are tetraploid with AVVV genomes. Sizes of flowers as well as of sepals and petals generally show significant increases from diploid to tetraploid. This trend reflects the increasing influence of Vanda resulting from additional one and two Vanda genomes in triploid and tetraploid respectively as compared to diploid cultivars. Among the three genomic classes, diploid cultivars generally bear less flowers per spray than those of triploid and tetraploid although exceptions may occur. There is no clear trend in the length of inflorescences although diploid cultivars tend to have less compact spray with flowers more distantly spaced out.  相似文献   

Genetic variation of the rate of leaf appearance in maize: Possible yield prediction at the early stage     

Y. Hébert 《Euphytica》1990,46(3):237-247

Summary Evidence of genetic variation for early vigour is presented using maize line × tester crosses. The leaf appearance rate and associated variance components are affected by a physiological stress attributable to the transition to autotrophic nutrition by the plant. At this stage, specific combining ability plays an important role in the total genetic variation. It is concluded that differing genetic controls exist in early and late material, and that this difference is also manifested in leaf initiation and elongation rates. The ground coverage rate, as a component of plant development, is genetically correlated to total dry matter yield. The genetic correlations vary according to the growth stage.  相似文献   

Sodium bicarbonate reduces postharvest decay development on melons   总被引：1，自引：0，他引：1  

Y. Aharoni  E. Fallik  A. Copel  M. Gil  S. Grinberg  J.D. Klein 《Postharvest Biology and Technology》1997,10(3):201-206

Sodium bicarbonate (SBC) inhibited in vitro mycelial growth of A. alternata, Fusarium spp. and R. stolonifer. SBC action was fungistatic rather than fungicidal. Coating commercially harvested ‘Galia’ and ‘Ein-Dor’ melons with wax containing 2% SBC reduced decay incidence after storage and shelf life simulation by four to seven-fold, to a commercially acceptable level of 6–7%, compared to untreated or waxed-treated controls. This treatment also maintained the fresh and blemish-free appearance of the fruit at harvest. Higher concentrations of SBC (3%) were phytotoxic and significantly reduced general fruit appearance. A trial shipment by sea transport to Europe demonstrated that 2% SBC incorporated into a wax coating maintained the marketability of ‘Galia’ melon fruits compared to that of untreated fruit. SBC can be an alternative biocide to the fungicide imazalil, thus eliminating unwanted residues on melon fruits.  相似文献   

Amplified fragment length polymorphism- and simple sequence repeat-based molecular tagging and mapping of greenbug resistance gene Gb3 in wheat   总被引：3，自引：0，他引：3  

Y. Weng  M. D. Lazar 《Plant Breeding》2002,121(3):218-223

The greenbug, Schizaphis graminum (Rondani), is the most economically damaging aphid pest of wheat in the southern Great Plains of the USA. In this study, the single, dominant greenbug resistance gene, Gb3, was molecularly tagged and genetically mapped using amplified fragment length polymorphism (AFLP) and simple sequence repeat(SSR) markers. Three AFLP loci were associated with the Gb3 locus in linkage analysis with 75 F_2:3 families from the cross between two near‐isogenic lines (NILs) for Gb3,‘TXGBE273’ and ‘TXGBE281′. Two of these loci, XMgcc Pagg and Xmagg Patg cosegregate with Gb3 in the population analysed. Further analysis indicated that XMgcc Pagg and Xmagg Patg are specific for the Gb3 locus in diverse genetic backgrounds. Two SSR markers, Xgwm111 and Xgwm428 previously mapped in wheat chromosome 7D, were shown to be linked with Gb3, 22.5 cM and 33.1 cM from Gb3, respectively, in an F₂ population of ‘Largo’בTAM 107’, suggesting that Gb3 is located in the long arm of chromosome 7D. The two AFLP markers cosegregating with Gb3 are valuable tools in developing molecular markers for marker‐assisted selection of greenbug resistance in wheat breeding.  相似文献   

The effect of temperature during growth and flowering on the seed set of tetraploid freesia     

Y. O. Kho  J. Baër 《Euphytica》1973,22(1):35-38

Summary Phytotron experiments have been carried out to study the effect of different temperatures on the seed set of tetraploid freesias during the raising of the plants and at the time of flowering and pollination.The effect of a relatively low temperature during the growth period is reflected in a comperatively greater number of flowers as a result of an increase in number of ramifications of the peduncle. This sometimes promotes the seed yield notwithstanding that the lower temperature reduces the fertility of each seperate flower. It is clearly proved that the temperature during flowering and pollination affects the fertility of the flower and the ultimate seed yield of the plant. Experiments in our phytotron showed 14°C during the growth period and 20°C at the time of pollination to be the optimum combination for a good seed yield.The effect of a lower night temperature was generally favourable, particularly so when measured by the number of seeds per pollinated flower.  相似文献   

Cytological and genetical studies of a male sterile celery   总被引：6，自引：0，他引：6  

C. F. Quiros  A. Rugama  Y. Y. Dong  T. J. Orton 《Euphytica》1986,35(3):867-875

Summary The inheritance and nature fo male sterility of a cerley (Apium graveolens L.) strain (MS1) is reported. Male sterility in MS1 is determined by a a recessive genotype for a single locus. Tests for linkage with the isozyme chromosome markers SDH-1 and PGM-1 were negative. MS1 male sterility was associated with a defective tapetum characterized by prominent vacuoles and premature degeneration. The stamens in the male sterile strain persisted in the flowers up to stigma receptivity, while in the male fertile plants they dropped before style expansion. The male sterile flowers produced normal amounts of nectar, resulting in cross pollination by various species of pollinators. It was estimated that the sterile strain produced 30% less seed than normal male fertile. Its possible use for hybrid celery seed production is discussed.Research supported by grants from the California Celery Research Board and BARD I-483-82.  相似文献   

Characterization of graft-induced change in capsaicin content of Capsicum annuum L.     

N. Yagishita  Y. Hirata  K. Okochi  K. Mimura  H. Mizukami  H. Ohashi 《Euphytica》1985,34(2):297-301

Summary Capsaicin contents were measured in the progenies from the test crosses between the strain, G₅S₁₇ derived from fruit with the graft-induced change in fruit shape and the original two cultivars, Yatsubusa (Capsicum annuum L. var fasciculatum Ilish) and Spanish Paprika (C. annuum L. var. grossum Sendt) used for grafting.The strain, G₅S₁₇ contained a lower amount of capsaicin than the original pungent cultivar Yatsubusa used as scion. The characteristic of the lowered capsaicin content in the strain has been stably inherited through seed propagation, and has also been transmitted to the progenies from the crosses with the original two cultivars used for scion or stock. These features in the capsaicin content agreed with those in fruit shape in the graft-induced change.  相似文献   

Somaclonal variation in three Argentinean varieties of Triticum aestivum with different karyotypic instability*     

P. M. Franzone  E. Y. Surez  R. M. Solari  E. A. Favret  R. D. Rios  A. H. Díaz Paleo 《Plant Breeding》1996,115(2):89-93

Three cultivars of wheat showing different levels of spontaneous karyotypic instability were studied regarding their stability in vitro for a number of characters, i.e. chromosome structure, gliadin pattern, glume and grain colour, awn type, chlorophyll pigmentation and plant morphology. The progenies of somaclones derived from immature embryos of both aneuploid and euploid plants were used in this study along with foundation seeds and a large number of their sexual progeny in order to discriminate between pre-existent variability and any novel variation induced by the in vitro culture. Only one translocation not described before and a new gliadin pattern were detected which could be ascribed to the effects of tissue culture, suggesting that this technique is not effective for inducing novel variation for breeding purposes in wheat.  相似文献