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111.
为探讨我国西南地区玉米地方品种Glb 1基因序列多态性,对40份西南地区玉米地方品种的Glb 1基因序列测序,并与Gen Bank中来自普通玉米、小颖玉米、繁茂玉米和摩擦禾的19条同源序列比对。结果表明,来自西南地区四川、重庆、云南和贵州的玉米地方品种分别有35、25、33和25个多态性位点,其遗传多态性分别是小颖玉米的87%、86%、85%和71%,8个种群遗传多态性指数的大小排序为小颖玉米、四川地方品种、重庆地方品种、云南地方品种、贵州地方品种、普通玉米、磨擦禾和繁茂玉米,Tajima’D、FuLi’D和FuLi,F检验表明Glb 1基因是中性进化基因。比较种群间DNA序列的共有多态性和固定差异,玉米地方品种与小颖玉米、繁茂玉米、磨擦禾间存在较高的固定差异和较低的共有多态性。Glb 1基因的系统进化关系及网状关系分析为玉蜀黍属的分类系统提供了佐证,四川玉米地方品种有较高的遗传多态性支持我国玉米由印度经西藏传入四川的论点。 相似文献
112.
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
113.
A. N. Mishra K. Kaushal G. S. Shirsekar S. R. Yadav R. N. Brahma H. N. Pandey 《Plant Breeding》2005,124(5):514-516
The bread wheat cultivar ‘Thatcher’ is documented to carry the gene Lr22b for adult‐plant resistance to leaf rust. Seedling‐resistance to leaf rust caused by Puccinia triticina in the bread wheat cultivar ‘Thatcher’, the background parent of the near‐isogenic lines for leaf rust resistance genes in wheat, is rare and no published information could be found on its genetic basis. The F2 and F3 analysis of the cross ‘Agra Local’ (susceptible) × ‘Thatcher’ showed that an apparently incompletely dominant gene conditioned seedling‐resistance in ‘Thatcher’ to the three ‘Thatcher’‐avirulent Indian leaf rust pathotypes – 0R8, 0R8‐1 and 0R9. Test of allelism revealed that this gene (temporarily designated LrKr1) was derived from ‘Kanred’, one of the parents of ‘Thatcher’. Absence of any susceptible F2 segregants in a ‘Thatcher’ × ‘Marquis’ cross confirmed that an additional gene (temporarily designated LrMq1) derived from ‘Marquis’, another parent of ‘Thatcher’, was effective against pathotype 0R9 alone. These two genes as well as a second gene in ‘Kanred’ (temporarily designated LrKr2), which was effective against all the three pathotypes, but has not been inherited by ‘Thatcher’, seem to be novel, undocumented leaf rust resistance genes. 相似文献
114.
Summary The merits and limitations of somatic cell techniques involving Agrobacterium-mediated transformation, direct gene transfer and protoplast fusion, are discussed in relation to the genetic improvement of forage and grain legumes. Whilst progress with legumes is limited compared to that with plants of other families such as the Solanaceae, the fact that many legumes are readily amenable to tissue culture now permits somatic cell techniques to be targetted to these species. Future development of the subject will necessitate close collaboration between molecular biologists and plant breeders to enable novel plants generated by in vitro technologies to be incorporated into conventional breeding programmes. 相似文献
115.
116.
Brian J. Steffenson 《Euphytica》1992,63(1-2):153-167
Summary Since the mid-1940's, barley cultivars grown in the northern Great Plains of the USA and Canada have been resistant to stem rust caused byPuccinia graminis f. sp.tritici. This durable resistance is largely conferred by a single gene,Rpg1, derived from a single plant selection of the cultivar Wisconsin 37 and an unimproved Swiss cultivar. At the seedling stage, barley genotypes withRpg1 generally exhibit low mesothetic reactions at 16–20° C and slightly higher mesothetic reactions at 24–28° C to many stem rust pathotypes. This resistance is manifested by a low level of rust infection and mostly incompatible type uredia on adult plants.Rpg1 reacts in a pathotype-specific manner since some genotypes ofP. g. f. sp.tritici are virulent on cultivars carrying this gene in the field. Several factors may have contributed to the longevity of stem rust resistance in barley, a) since barley is planted early and matures early, it can sometimes escape damage from stem rust inoculum carried from the south; b) one or more minor genes may augment the level of resistance already provided byRpg1; c) the cultivation of resistant wheat cultivars and eradication of barberry have reduced the effective population size and number of potential new pathotypes ofP. g. f. sp.tritici, respectively; and d) virulent pathotypes ofP. g. f. sp.tritici andP. g. f. sp.secalis have not become established. This situation changed in 1989 when a virulent pathotype (Pgt-QCC) ofP. g. f. sp.tritici became widely distributed over the Great Plains. However,Rpg1 may still confer some degree of resistance to pathotype QCC because stem rust severities have been low to moderate and yield losses light on barley cultivars carrying the gene during the last four seasons (1989–1992). Several sources of incomplete resistance to pathotype QCC have been identified in barley. To facilitate the transfer of resistance genes from these sources into advanced breeding lines, molecular marker assisted selection is being employed. 相似文献
117.
Summary Seven single-plant selections of wild emmer, with temperature-sensitive minor-effect genes for stripe rust resistance, were intercrossed in eight combinations. The resulting progenies were studied for a possible additive gene action.The transgressive segregation towards resistance in F2 observed in all the combinations indicates that additive gene action for resistance indeed occurs in wild emmer. The common occurrence of this phenomenon in random combinations suggests further that several minor-effect genes are involved.Following selection of the most resistant plants in F2, a marked shift towards resistance was noted in F3, which demonstrates a positive response to selection. In some instances, additive resistance selected for (in F2) at the high temperature-profile was expressed (in F3) also at the low temperature-profile. This kind of resistance, when utilized in breeding programmes, promises therefore to be effective over a range of temperatures. 相似文献
118.
Transformation efficiency of melon is low and is still regarded as a challenge. In this paper, the regeneration and transformation response of ‘BU‐21/3′, a newly characterized melon breeding line, is described. The line seems to be superior in this regard to previously evaluated genotypes. Agrobacterium‐mediated delivery of the GUS or GFP reporter genes into cotyledon explants was used to evaluate efficiency of transient and stable transformation. Good transient expression was observed, and stable transformation frequencies of 0.4‐1.5 transgenic shoots per explant were obtained. Transgenic plantlets were transferred to a contained greenhouse as early as 8‐10 weeks after transformation. Transgenic plants are fertile and exhibit a true‐to‐type phenotype. The ‘BU‐21/3’ line may become a useful tool for the facilitation of transgenic breeding in melon. 相似文献
119.
Genetic control of flowering time in sorghum was investigated using a recombinant inbred lines population derived from a cross
between IS 2807, a slightly photoperiod sensitive tropical caudatum landrace, and IS 7680,a highly photoperiod sensitive tropical
guinea landrace. Progenies were sown with their parents at six different dates between 1995 and 1997 in Burkina Faso. Direct
field measures and synthetic measures derived from the implementation of a model were used to characterize the photoperiod
response. Emphasis was put to identify the most relevant traits to account for Basic Vegetative Phase (BVP) and photoperiod
sensitivity sensus stricto. One QTL was detected on Linkage Group (LG) F for the traits related to BVP. Two QTLs were detected on LGs C and H for the
traits related to the photoperiod sensitivity sensus stricto. This gives credit to at least partially independent genetic determinisms for those two components of photoperiod response.
Evidences for possible orthology of the QTLs detected here with other QTLs and major genes involved in flowering time of sorghum
and rice are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
120.
J. L. Molina-Cano J. L. Montoya J. Echarte C. Royo J. Serra J. P. Marin-Sanchez 《Plant Breeding》1992,109(1):40-45
Twenty-four near-isogenic barley lines, with a cv.‘Pallas’ background, carrying different mildew resistance genes were subjected in 1987, 1989 and 1990 to natural infection by the pathogen at several different and contrasting Spanish sites in order to study its virulence. The virulence genes proved to be geographically grouped into three regions: western (Valladolid), southern (Sevilla) and northern and northeastern (Navarra, Lleida and Girona). The mildew population of Lleida was more variable when compared with Navarra and Valladolid. Overall, the most effective resistance genes were: Ml-a13 + Ml-(Ru3), mlo and Ml-(1402). 相似文献