摘要:

AbstractAlthough a major component of fitness, male reproductive success is generally extremely difficult to estimate. As a result, genetic methods and maximum likelihood models have been developed to estimate male parentage, but all are limited in practice by the degree of genetic variation observable. Scoring individuals phenotypically at a large number of random loci exhibiting dominance (e.g. RAPD markers) may provide a means of detecting sufficient genetic variation. Dominance, however, represents a loss of information and therefore greater variation in the estimate of paternity. A mixture model describing mating in a population is presented to quantify the trade‐off between marker types when estimates of male fertility are sought. A sample size 1.5‐2.0 times greater is required for dominant markers under some conditions to obtain the same confidence in fertility estimates as for codominant markers, although with large sample sizes the fertility estimates are similar for either marker type. Since the number of dominant DN A markers is not limited in the same manner as is the number of codominant protein markers, one's confidence in the estimates can be increased above that possible from proteins by surveying additional loci. However, for a fixed sample size a trade‐off exists between the number of progeny assayed per female and the number of loci surveyed. In many cases more progeny per female provide better estimates of fertility than more

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00020.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractRegions of DNA containing promoter sequences from aPseudomonas syringaepv.phaseolicola‐specific phage (φ11P) were identified by shotgun cloning into a broad‐host‐range promoter‐probe vector (pQF70). When used in conjunction with the luciferase reporter genes, one of these DNA fragments, 19H, directed gene expression at a level which enabled the subsequent light output (bioluminescence) of single cells ofP. syringaepv.phaseolicolato be detected and visualized using a charge‐coupled device (CCD). TheP. syringaepv.phaseolicolaφ11P, 19H andP. aeruginosaφPLS27, HcM promoters gave a 50‐fold increase in bioluminescence (maximum relative light output) compared to similar constructs containing other well‐characterized promoters, for example, tetracycline. Similar bioluminescent characteristics of the transformed bacterium, were observed during growth with and without antibiotic‐selection. Whenlux+bacteria were inoculated onto French bean leaf (Phaseolus vulgarisL.), the resultant secondary halo blight lesions were bioluminescent and during phylloplane colonization by thelux+bacterium, bioluminescence on leaf surfaces was detected and imaged by the CCD. Use of these newly identified promoters, combined with the greatly increased sensitivity of bioluminescence detection by the CCD, thus provided a new dimension for the study of natural ecological populations during the bacterial colo

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00021.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSeventy‐two rhizobial strains were isolated from the root nodules of french beans (Phaseolus vulgaris). They were sampled from two geographically distant field populations and 18 additional different sites in France. They were characterized by a) plasmid profiles, (b) RFLP analysis of total cellular DNA using various chromosomal and symbiotic gene probes (includingnifH fromRhizobium etlibv.phaseoli) and c) their ability to nodulate a potential alternative host,L. leucocephala.Over half of the isolates were ascribed toRhizobium leguminosarumbv.phaseolion the basis of the hybridization analysis, the possession of multiple copies ofnifH and their inability to nodulateL. leucocephala.The remaining isolates belonged to 2 groups which were shown to be genomically distinct fromR. leguminosarumbv.phaseoli, R. etlibv.phaseoliandR. tropici.Most members of these two groups shared withR. tropicithe ability to nodulateL. leucocephalaand, for isolates of only one of these groups, the presence of one copy ofnifH. Members of each of the 3 taxa were widely distributed in France and circumstantial evidence of pSym transfer between them was shown.R. leguminosarumbv.phaseoliand one of the two novel groups co‐occurred within the two geographically distant populations. Individual genotypes were conserved between them. The finding of a third taxon at various other locations indicated additional diversity among rhizobia nodulating be

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00022.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSurvival and respiratory activity of a genetically engineeredPseudomonas aureofaciensPs3732RNL11 were compared to the parental wild‐typeP. aureofaciensPs3732RN in loam and sandy loam soils over 17‐ and 28‐day periods. Survival and respiratory activity ofP. aureofaciensPs3732RNL11 was not statistically significantly different from that ofP. aureofaciensPs3732RN. Soil texture had an effect on respiratory activity; carbon dioxide evolution was significantly higher in the sandy loam soil. This effect was observed on days 2, 10 and 18 but not on day 24. The presence ofP. aureofaciensPs3732RNL11 and Ps3732RN did not significantly affect growth of whitebean (Phaseolus vulgarisL.) in vermiculite, loam, or sandy loam soils. There was no significant difference (95% level) in numbers of nodules produced in the presence ofP. aureofaciensPs3732RNL11 and Ps3732RN as a result of the symbiotic relationship betweenRhizobium phaseoliand the whitebean roots in vermiculite. Enumeration of nodules on whitebean roots in loam and sandy loam soils was not conducted due to difficulties in removing intact roots from the

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00023.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractFor organisms in which direct observation of mating and subsequent dispersal of offspring and relatives is impossible, patterns of reproductive success and genealogical relationship can only be established using genetic markers. The ideal genetic assay would (1) employ highly polymorphic genetic markers for distinguishing among individuals; (2) use little tissue for analysing early life‐history stages; and (3) require minimal investment in time and money for population level studies. From this perspective, DNA polymorphisms revealed by PCR amplification using random ten‐base primers [Randomly Amplified Polymorphic DNA (PCR‐RAPD) or Arbitrarily Primed DNA (AP‐PCR)] have great potential. However, the evidence that RAPD/AP markers are both heritable and can be repeatably amplified remains controversial. This study characterizes patterns of inheritance and polymorphism of RAPD markers in the free‐spawning, colonial marine hydrozoanHydractinia symbiolongicarpus.In all cases, the amplification products were identical among extractions from the same clone. Of 56 primers screened, 13 had sufficient polymorphism and scoreability for an analysis of parentage and higher‐order genetic relationships in three matings. These primers generated 156 unique amplification products (putative loci), of which 133 were polymorphic. All but four of these loci were inherited as dominant mendelian markers. Our study suggests that the presence of a marker represents a single allele at a locus; however, what appear to be single null alleles may actually comprise several segregating alleles. When the identity of neither parent was known a priori, inclusion (unique markers present in offspring and only one of the potential parents) proved to be more efficient than exclusion for assigning offspring to parents. The most powerful approach, however, was cluster analysis of all presence/absence information for the marker bands. Clustering avoided the pitfalls caused by the appearance of occasional nonparental bands, and constructed a hierarchical framework that correctly reflected all genealogical re

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00024.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe ability to increase crop disease resistance by using transgenic (TG) means has recently been demonstrated for several crops. The current TG procedures alter the temporal expression of transgene pathogenesis‐related (PR) proteins, so that the usually inducible PR proteins are expressed constitutively in the foreign host. The constitutive expression of the transgene PR protein chitinase is believed to increase the host's nonspecific basic resistance to pathogens. A potential nontarget effect of constitutively expressing chitinase may be a decrease in the activity of beneficial microbes, especially vesicular‐arbuscular mycorrhizal fungi. The decrease in activity of mycorrhizal fungi is related to reduced susceptibility of TG plant roots to colonization by these fungi, which is in turn associated with lysis of fungal cell walls by the constitutively expressed chitinase. An argument is presented that use of TG means to alter the temporal expression of PR proteins ignores a legacy of past evolutionary trade‐offs in vascular plants. A major nontarget effect of expressing transgene chitinase is a reduction in the susceptibility of roots to colonization by mycorrhizal fungi. This reduction in mycorrhizal susceptibility occurs without alteration of the mycorrhizal dependence of the host on symbiont‐supplied nutrients. Data are presented in support of this contention that demonstrate a strong negative association between host pathogen resistance and mycorrhizal colonization. An ecological consequence of reducing mycorrhizal colonization is a decrease in the soil's mycorrhizal propagule reserve that diminishes the next crop's production, especially under low‐input cropping practices. A further consequence that has both ecological and evolutionary outcomes is the escape of the transgene for improved pathogen resistance into wild populations. By increasing a crop's disease resistance by TG means, we may inadvertently be creating a ‘super weed’ when the TG plant or the transgene escapes into wild relatives through hybridization. Hybridization of wild relatives with TG plants would be especially relevant for crops, such as sugar beet, rapeseed, and many modern cereal cultivars that have close relatives in the wild but have a relatively low requirement for symbiont supplied nutrients or are

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00025.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY