共查询到20条相似文献，搜索用时 31 毫秒
1.
Summary The inheritance of resistance to coffee berry disease (CBD) has been studied by applying a preselection test to F2 progenies of a half diallel cross between 11 coffee varieties with different degrees of resistance and to sets of parental, F1, F2, B11 and B12 generations of crosses between resistant and susceptible varieties. True resistance to CBD appears to be controlled by major genes on three different loci. The highly resistant variety Rume Sudan carries the dominant R- and the recessive K-genes. The non-allelic interaction between these two genes is of a duplicate nature. The R-locus has multiple alleles with R
1R1alleles present in Rume Sudan and the somewhat less effective R
2R2alleles in a variety like Pretoria, which also has the K-gene. The moderately resistant variety K7 carries only the recessive K-gene. The arabica-like variety Hibrido de Timor (a natural interspecific arabica x robusta hybrid) carries one gene for CBD resistance on the T-locus with intermediate gene action. It probably inherited this gene from its robusta parent. There is circumstantial evidence that the resistance to CBD is of a stable nature, but it is advisable to accumulate in one genotype as many resistance genes as possible by combining in the breeding programme the resistance of Rume Sudan with that of Hibrido de Timor. 相似文献
2.
The influence of temperature on the resistance to powdery mildew, caused by Blumeria graminis (DC.) E.O. Speer f. sp. tritici
Em. Marchal, was evaluated on six wheat cultivars/lines, Axminster/8* Chancellor (Cc) (Pm1), Chul/8*Cc (Pm3b), Yuma/8*Cc (Pm4a), VPM1 (Pm4b), Kavkaz (Pm8), and Chancellor, at two temperatures of 25EC and 15EC with two isolates of powdery mildew.
Resistance, based on the components of latency period, infection type, colony number per unit leaf area, per cent infected
leaf area, and AUDPC, was much less effective at 15EC than at 25EC for VPM1 and Yuma/8*Cc, but no resistance shift was observed for Kavkaz and Axminster/8*Cc, indicating the difference of temperature-sensitivity among Pm genes or among the interactions of individual host genes
with corresponding powdery mildew pathogen genes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Qualitative observations of Hevea spp. resistance to Phyllachora huberi were carried out on 200 clones in a collection and 21 full-sib progenies under natural conditions of infestation. A total
of 42 clones, mostly originating from the natural range of the Hevea genus, and at least two species (H. brasiliensis and H. benthamiana) revealed total resistance to the parasite. For nine of the thirteen `resistant ×susceptible' and `resistant × resistant'
progenies studied, the ratio of susceptible: resistant plants suggested the existence of a total resistance mechanism produced
by a dominant allele at a single locus for the P. huberi race(s) present at the study site. For three of the progenies involving the same resistant parent, it was possible to locate
the gene (called Phr) at 14.7 cm from the adhisozyme locus.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Summary Chickpea (Cicer arietinum L.) line ICC 1069 was selected as resistant parent after screening for resistance to grey mould (Botrytis cinerea Pers.) under artificial inoculation conditions. It was crossed with four high yielding susceptible varieties of chickpea. Crosses ICC 1069 × BGM 413 and ICC 1069 × BG 256 showed monogenic dominant resistance in ratio of 3R (resistant): 1S (susceptible). However, in crosses, ICC 1069 × BGM 419 and ICC 1069 × BGM 408, a ratio of 13S (susceptible) : 3R (resistant) was obtained indicating the presence of epistatic interaction. The results pointed towards the presence of a type of major gene resistance to grey mould in chickpea. 相似文献
5.
Summary Three triticale lines, Siskiyou, M2A-Beagle, and OK 77842 have been reported to possess resistance to bacterial leaf streak caused by Xanthomonas campestris, pv. translucens (Xct.). The three resistant lines were crossed to susceptible lines and crossed with each other. F2, BC1-F1, BC2-F1 plants were inoculated with a mixture of two Xct strains. The segregation data indicate the presence of a single dominant gene in each of the three resistant lines to bacterial leaf streak. These three genes are either the same or closely linked herein designated as Xct1. 相似文献
6.
Ietje W. Boukema 《Euphytica》1980,29(2):433-439
Summary The genes for resistance to pepper strains of TMV in five C. chinense
Jacq. accessions, the PI numbers 152225, 159236, 315008, 315023 and 315024, were investigated for allelism. The resistance of these five C. chinense accessions was found to be inherited monogenically and to be partially dominant. The resistance genes in these accessions appeared to be allelic and were also found to be allelic with the known alleles L1 and L. It is proposed to use the symbol L3 for these resistance genes. 相似文献
7.
Reuben Tendo Ssali Andrew Kiggundu Jim Lorenzen Eldad Karamura Wilberforce Tushemereirwe Altus Viljoen 《Euphytica》2013,194(3):425-430
Fusarium wilt of bananas (also known as Panama disease), caused by the soil-borne fungus Fusarium oxysporum f. sp cubense (Foc), is a serious problem to banana production worldwide. Genetic resistance offers the most promising means to the control of Fusarium wilt of bananas. In this study, the inheritance of resistance in Musa to Foc race 1 was investigated in three F2 populations derived from a cross between ‘Sukali Ndizi’ and ‘TMB2X8075-7’. A total of 163 F2 progenies were evaluated for their response to Fusarium wilt in a screen house experiment. One hundred and fifteen progenies were susceptible and 48 were resistant. Mendelian segregation analysis for susceptible versus resistant progenies fits the segregation ratio of 3:1 (χ2 = 1.72, P = 0.81), suggesting that resistance to Fusarium wilt in Musa is conditioned by a single recessive gene. We propose panama disease 1 to be the name of the recessive gene conditioning resistance to Fusarium wilt in the diploid banana ‘TMB2X8075-7’. 相似文献
8.
Summary Eight spring barley cultivars, respresenting the known range in partial or slow rusting resistance to leaf rust, Puccinia hordei, were investigated for their effects on the components of partial resistance; infection frequency, latent period, infectious period and spore production per uredosorus per day. Considerable variation was observed among the cultivars for each of the components. The cultivar effects on the components tend to be associated. Cultivar L94 for instance, shows the highest infection frequency, the shortest latent period and a long infectious period. Julia and Vada both have a low infection frequency, a long latent period and a low spore production per sorus per day. This association, though, is only a partial one.The total spore production per unit leaf area (the combined result of the four components) appeared highly correlated with the partial resistance in the field (r=0.85). Only a relatively small portion of the variation in partial resistance cannot be explained by the four components studied. Several other aspects, which might affect the rate of epidemic development, are discussed.Latent period, measuring the onset of the new spore production, estimated partial resistance as well as total spore production did (r=–0.85). In order to evaluate the partial resistance of barley genotypes in the greenhouse the latent period is preferred above total spore production as it is measured more easily, more accurately and sooner after inoculation. 相似文献
9.
The inheritance of seedling resistance to a Swedish isolate of Pyrenophora teres f. teres was investigated in four resistance sources of spring barley. Accessions CI 2330, CI 5791, CI 5822 and CI 9779 were used as resistance sources, and the cultivar ‘Alexis’ was used as a susceptible parent in different crosses. From the disease reaction in the F1, F2 and F3 generations it was concluded that the resistance was governed by the same two complementary genes in CI 5791, CI 822 and CI 9776. One of these genes was present in CI 2330. The first three cultivars were highly resistant to the isolate used in this investigation. These results, when combined with earlier studies, suggest that CI 5791, CI 5822 and CI 9776 may be of great value as sources of resistance to barley net blotch. Spearman's rank correlation between the disease reaction of F2 plants and their F3 progeny was highly significant (r = 0.75; P ≥ 0.001) It is suggested that selection in the F2 generation is effective. In a backcross breeding scheme, single plant reactions in F1 or F2 need to be confirmed in later generations. 相似文献
10.
11.
A collection of 67 accessions of Pisum species originating from different countries was screened in a glasshouse test for resistance to Erysiphe pisi. All Pisum fulvum accessions were completely resistant. Incomplete resistance was identified in some accessions of P. sativum subsp. sativum var. arvense and P. sativum subsp. elatius and abyssinicum. Microscopy revealed several distinct cellular mechanisms governing resistance. In P. fulvum, it was mainly due to a high frequency of cell death that occurred both as a rapid response to attempted infection and a delayed response that followed colony establishment. Cell death following colony establishment was also key to the incomplete resistance in some accessions of P. sativum subsp. sativum var. arvense. In addition, impaired spore germination, and to a lesser extent appressorium formation, contributed to pre‐penetration resistance in some accessions. In some cases, resistance also retarded colony growth, possibly through effects on haustorial development or function in cells that survived the attack. Thus, these wild pea accessions offer diverse resistances that could be introduced to cultivated peas to increase the efficacy of powdery mildew resistance. 相似文献
12.
Summary A new test procedure for measuring shatter-resistance of siliquae of Brassica spp. is described. A siliqua with its proximal end clamped is loaded as a cantilever in a testing machine. The maximum bending moment, the corresponding stiffness and the energy to cause the siliqua to rupture were taken as measures of the resistance of the siliqua to shatter. Studies showed that ranking of accessions based on either bending moment or energy closely approximated the rankings based on observations of field shatter. A reasonably high significant negative correlation was found between percentage of shattered siliquae and both bending moment and energy (r=–0.595 and –0.531 respecitvely, P=0.001). The above results indicated that bending moment and energy could be used as criteria in evaluating rapeseed genotypes for shatter-resistance in breeding programmes. 相似文献
13.
Summary Resistance to fusarium wilt, incited by Fusarium oxysporum (Schlecht.) f. sp. lycopersici (Sacc.) Snyder & Hansen race 3 in tomato (Lycopersicon esculentum Mill.) was discovered in LA 716, a L. pennellii accession. A resistant BC1F3 breeding line, E427, was developed from LA 716. E427 was crossed with the susceptible cv. Suncoast and F1, BCP1, BCP2 (to Fla 7155, a susceptible parent) F2, F3, and BCP2S1 seeds were obtained. Segregation for resistance following root dip inoculation over three experiments indicated a single dominant gene controlled resistance. Five of the 12 BCP1S1's segregated more susceptible plants, whereas one of the 12 segregated more resistant plants than expected (P<0.05). Three of 23 F3 lines segregated more susceptible plants than expected while 1 of the 23 had more resistant plants than expected (P<0.05). Segregation in all other lines fit expected ratios. Five of the 23 F3's were homozygous resistant which was an acceptable fit to expectations (P=0.1–0.5). The gene symbol I
3 is proposed for resistance to race 3 of the wilt pathogen. Deviations from expected ratios in data reported here and for other breeding lines indicate an effect of modifier genes and/or incomplete penetrance. Plant age at inoculation and seed dormancy did not affect results.Florida Agricultural Experiment Station Journal Series No. 8101. 相似文献
14.
Summary Atrazine resistant Brassica napus × B. oleracea F1 hybrids were backcrossed to both parental species. The backcrosses to B. napus produced seeds in both directions but results were much better when the F1 hybrid was the pollen parent. Backcrosses to B. oleracea failed completely but BC1s were rescued by embryo culture both from a tetraploid hybrid (2n = 4x = 37; A1C1CC) and sesquidiploid hybrids (2n = 3x = 8; A1C1C). Progeny of crosses between the tetraploid hybrid and B. oleracea had between 25 and 28 chromosomes. That of crosses between the sesquidiploid hybrid and B. oleracea had between 21 and 27. A few plants that had chromosome counts outside the expected range may have originated from either diploid parthenogenesis, unreduced gametes or spontaneous chromosome doubling during in vitro culture. Pollen stainability of the BC1s ranged from 0% to 91.5%. All the BC1s to B. oleracea were resistant to atrazine. 相似文献
15.
海南辣椒品种对疮痂病的抗性鉴定 总被引：1，自引：0，他引：1
田间自然发病调查结果表明，18个海南反季节栽培辣椒品种中，只有海南黄帝椒对疮痂病表现免疫，12个品种表现中抗，其余均表现感病或高感。 相似文献
16.
A total of 4,681 accessions of Hordeum vulgare landrace material from Ethiopia, East Mediterranean, Near East, Nepal and China
were sown in the field and subjected to the natural powdery mildew epidemic in Denmark. Apparently resistant accessions were
selected. Selfed progeny from them were retested and reselected in subsequent years at four locations in Denmark. Finally,
16 promising donors of resistance were retained. They were characterized in the field and tested in the seedling stage for
reaction to up to 72 different isolates of the powdery mildew fungus. The absence of the corresponding virulences in the Danish
airborne powdery mildew population was ascertained in five years. The resistances in the 16 donors are apparently mutually
different and from known sources of powdery mildew resistance in barley.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
18.
O. M. B. De Ponti 《Euphytica》1978,27(2):435-439
Summary For several generations subpopulations of the twospotted spider mite were reared on cucumber varieties previously selected as partially resistant. Subsequently resistance tests were carried out in the laboratory and the glasshouse with mites from these subpopulations and concurrently with mites from a basic population reared on a susceptible cucumber line. In these tests neither acceptance nor net reproduction or damage index on the partially resistant varieties depended on the kind of mite populations used as inoculum. Therefore it is concluded that the resistance is genuine. The stability of the resistance is discussed. 相似文献
19.
Selection for resistance to Plasmodiophora brassicae
Wor. in oriental subspecies of Brassica rapa L.
Summary Selection for resistance to Plasmodiophora brassicae
Wor. in oriental groups of Brassica rapa L.Two hundred and sixty-five cultivars of leafy, oriental bassicas were tested for resistance to 18 collections of Plasmodiophora brassicae, the causal agent of clubroot. The tests were conducted in the greenhouse at low and high level inoculum concentrations. Eleven cultivars of B. rapa pe-tsai, five cultivars of B. rapa pak-choy and three cultivars of B. rapa choy-sum consistently segregated for resistance at the lower concentration of inoculum (1000 spores/ml). All 265 cultivars were susceptible at the higher concentration (1 000 000 spores/ml). Three cultivars were used in pedigree and recurrent selection schemes for increased resistance. After three cycles of selfing resistant individuals, significantly more resistant S3 lines were derived from each cultivar. Lines derived from two cultivars. Chinese White and PI 257236, continued to improve with each cycle of selection and demonstrated increased resistance to higher levels of inoculum (up to 1 000 000 spores/ml) New cultivars based on intercrosses of S2 resistant individuals also had significantly better resistance than the original cultivar. After two cycles of selection in the third cultivar, PI 419007, resistance did not increase and its S2 mass did not differ significantly from the original cultivar. Evidence that indicates resistance is pathotype-non-differential and offers an alternative to major gene, pathotype-differential types of resistance currently being introduced to the leafy oriental brassicas from other Brassica rapa groups. 相似文献
20.
W. E. van de Weg 《Euphytica》1989,42(3):233-240
Summary To find a fast and reliable test to assess resistance to Nectria galligena in apple, different methods of inoculation were compared using macroconidia of N. galligena and one-year-old cut shoots from mature trees of Cox's Orange Pippin, IVT 69078-19, James Grieve and Jonathan.With the best inoculation method 11 genotypes were screened for resistance. Elstar, Golden Delicious, Jonathan and Lombart's Calville were highly resistant and the level of resistance of Ingrid marie, Gloster, Melrose, IVT 69078-19, Cox's Orange Pippin, James Grieve and Idared decreased in this order.The best inoculation method proved to be simple, giving results within four to nine weeks after inoculation. 相似文献