不同细菌对家蝇幼虫抗菌蛋白/肽的诱导效应

利用抑菌圈测量法和毛细管电泳研究、比较不同细菌对家蝇Musca domesticaL.幼虫抗菌蛋白/肽的诱导效应。结果表明,家蝇幼虫受细菌诱导后抗菌活性比对照都有不同程度的增加,同时不同细菌诱导表达样品对于相应的诱导菌均表现很高的抗菌活性。毛细管电泳图谱表明鼠伤寒沙门氏菌Salmonella typhimurium50013诱导后抗菌蛋白/肽表达强度增加了50倍,其它细菌诱导后抗菌蛋白/肽表达强度增加了1～40倍。与G+细菌相比,G-细菌具有更强的诱导效应。结论:家蝇幼虫对不同的细菌刺激有特异性反应,即不同细菌诱导抗菌蛋白/肽的强度、种类和数量都不一致。     

滁州市家蝇对6种杀虫剂的抗药性调查

采用微量滴定法测定了滁州市家蝇对6种常见杀虫剂的抗药性。结果表明,滁州市的家蝇对毒死蜱、敌敌畏、高效氯氰菊酯、敌百虫、辛硫磷、溴氰菊酯6种常用杀虫剂都产生了很高的抗性,其LD50分别为1.1858、1.9505、0.9530、47.1834、1.2120、1.0053μg/只,相对抗性系数分别为49.62、139.32、207.17、263.59、390.97、1675.50。滁州应停止使用这些杀虫剂,加强对家蝇抗性对策的研究,延缓家蝇抗性的发展。     

Shaping the shoot: the relative contribution of cell number and cell shape to variations in internode length between parent and hybrid apple trees

Genetic control of plant size and shape is a promising perspective,particularly in fruit trees, in order to select desirable genotypes.A recent study on architectural traits in an apple progeny showedthat internode length was a highly heritable character. However,few studies have been devoted to internode cellular patterningin dicotyledonous stems, and the interplay between the two elementarycell processes that contribute to their length, i.e. cell divisionand elongation, is not fully understood. The present study aimedat unravelling their contributions in the genetic variationof internode length in a selection of F₁ and parent genotypesof apple tree, by exploring the number of cells and cell shapewithin mature internodes belonging to the main axes. The resultshighlighted that both the variables were homogeneous in samplescollected either along a sagital line or along the pith width,and suggest that cell lengthening was homogeneous during internodedevelopment. They allowed the total number of cells to be estimatedon the internode scale and opened up new perspectives for simplifyingtissue sampling procedures for further investigations. Differencesin internode length were observed between the genotypes, inparticular between the parents, and partly resulted from a compensationbetween cell number and cell length. However, genetic variationsin internode length primarily involved the number of cells,while cell length was more secondary. These results argue foran interplay between cellular and organismal control of internodeshape that may involve the rib meristem. Key words: Elongation, growth, histogenesis, Malusxdomestica Borkh, pith Received 2 January 2008; Revised 22 January 2008 Accepted 29 January 2008     

Dissecting apple tree architecture into genetic, ontogenetic and environmental effects: mixed linear modelling of repeated spatial and temporal measures

The present study aimed to dissect tree architectural plasticity into genetic, ontogenetic and environmental effects over the first 4 yr of growth of an apple (Malus x domestica) F1 progeny by means of mixed linear modelling of repeated data. Traits related to both growth and branching processes were annually assessed on different axes of the trees planted in a staggered-start design. Both spatial repetitions, (i.e. different axis types) and temporal repetitions (i.e. successive ages of trees) were considered in a mixed linear model of repeated data. A significant genotype effect was found for most studied traits and interactions between genotype and year and/or age were also detected. The analysis of repeated temporal measures highlighted that the magnitude of the decrease in primary growth is mainly determined by the first year of growth, and the decrease in bottom diameter increment is concomitant with the first fruiting occurrence. This approach allowed us to distinguish among the traits that were under genetic control, those for which this control is exerted differentially throughout tree life or depending on climatic conditions or an axis type. Mapping quantitative trait loci (QTL) that are specific to these different effects will constitute the next step in the research.     

Apple dwarfing rootstocks and interstocks affect the type of growth units produced during the annual growth cycle: precocious transition to flowering affects the composition and vigour of annual shoots

Background and Aims: Precocious flowering in apple trees is often associated witha smaller tree size. The hypothesis was tested that floral evocationin axillary buds, induced by dwarfing rootstocks, reduces thevigour of annual shoots developing from these buds comparedwith shoots developing from vegetative buds. Methods: The experimental system provided a wide range of possible treevigour using ‘Royal Gala’ scions and M.9 (dwarfing)and MM.106 (non-dwarfing) as rootstocks and interstocks. Second-yearannual shoots were divided into growth units corresponding toperiods (flushes) of growth namely, vegetative spur, extensiongrowth unit, uninterrupted growth unit, floral growth unit (bourse)and extended bourse. The differences between the floral andvegetative shoots were quantified by the constituent growthunits produced. Key Results: The dwarfing influence was expressed, firstly, in reduced proportionsof shoots that contained at least one extension growth unitand secondly, in reduced proportions of bicyclic shoots (containingtwo extension growth units) and shoots with an uninterruptedgrowth unit. In treatments where floral shoots were present,they were markedly less vigorous than vegetative shoots withrespect to both measures. In treatments with M.9 rootstock,vegetative and floral shoots produced on average 0·52and 0·17 extension growth units, compared with 0·77extension growth units per shoot in the MM.106 rootstock treatment.Remarkably, the number of nodes per extension growth unit wasnot affected by the rootstock/interstock treatments. Conclusions: These results showed that rootstocks/interstocks affect thetype of growth units produced during the annual growth cycle,reducing the number of extension growth units, thus affectingthe composition and vigour of annual shoots. This effect isparticularly amplified by the transition to flowering inducedby dwarfing rootstocks. The division of annual shoot into growthunits will also be useful for measuring and modelling effectsof age on apple tree architecture.     

SSRs isolated from apple can identify polymorphism and genetic diversity in pear

Apple simple sequence repeats (SSRs) were intergenerically applied to the characterization of 36 pear accessions, including 19 Japanese pears (Pyrus pyrifolia), 7 Chinese pears (P. bretschneideri, P. ussuriensis), 5 European pears (P. communis), 3 wild relatives (P. calleryana), and 2 hybrids between P. pyrifolia and P. communis. All of the tested SSR primers derived from apple produced discrete amplified fragments in all pear accessions. Nucleotide repeats were detected in the amplified bands by both Southern blot and sequencing analysis, and nucleotide sequences of pear were compared with those of apple. The differences in fragment size among pear or between pear and apple were, in many cases, due to the differences in repeat number. Interestingly, the DNA sequence of flanking regions in apple was highly conserved in pear. Hybrids from P. pyrifolia×P. communis showed one fragment inherited from each parent in all scorable cases, which suggested that each primer pair amplified fragments originating from the same locus. A total of 79 alleles were detected from seven SSR loci in pear, and all pear varieties except for the mutants could be differentiated. In conclusion, SSRs isolated from apple are highly conserved in pear and could be utilized as DNA markers in the latter genus. Received: 17 July 2000 / Accepted: 22 September 2000     

Re-examination of the self-incompatibility genotype of apple cultivars containing putative ’new’ S-alleles

Recently, the self-incompatibility (S-) genotypes of 56 apple cultivars were examined by protein analysis, which led to the identification by Boskovic and Tobutt of 14 putative ’new’ S-alleles, S12 to S25. This paper reports a re-examination of the S-genotypes of some of these cultivars through S-allele ’specific’ PCR and sequence analysis. The results obtained by this analysis indicated that the number of S-alleles that are present in apple is probably smaller than the number proposed by Boskovic and Tobutt. The existence of three ’new’ S-alleles (S20, S22 and S24) was confirmed. The existence of two other putative ’new’ S-alleles (S23 and S25) was, however, contradicted. The coding sequences of the S-alleles that correspond to the S10 and the S25 ribonuclease bands as well as those corresponding to the S22 and the S23 ribonuclease bands were shown to be identical in sequence. Interestingly, the S-allele corresponding to the S22 and the S23 ribonuclease bands shared a high sequence identity (99% identity) with S27, which was previously cloned and sequenced from Baskatong, but which was not included in the analysis conducted by Boskovic and Tobutt. Both S-alleles only differ in point mutations, which are not translated into differences in amino-acid sequence. To our knowledge, this is the first report of two S-alleles that differ at the nucleotide level but still encode for identical S-RNases. The implications of these observations for determining the S-genotypes of plants by PCR analysis or protein analysis are discussed. Received: 10 January 2001 / Accepted: 19 January 2001     

Relationship Between Growth, Secondary Metabolism, and Resistance of Apple

Abstract: The paper shows that N-induced vigorous shoot growth increases susceptibility of apple trees to Venturia inaequalis. This is due to a weakened defence in infected leaves of the high N cultures showing large lesions with excessive sporulation, whereas infected leaves from the low N cultures exhibited successful defence with only small chlorotic lesions and no sporulation. This might be explained by biosynthesis of phenylpropanoids in the young leaves of the resistant trees. A negative correlation between shoot growth of apple trees and the concentration of phenolic compounds in young leaves was found. Studies on in vitro shoot cultures revealed that the availability of sugars for the phenylpropanoid pathway is a strong regulatory factor. The ratio of sucrose and nitrogen in the medium influenced the total level of secondary products in the in vitro grown plantlets. Moreover, the relative deficiency of sugars was responsible for a metabolic block mainly at the level of glucosyl transferase and concomitant aglycone accumulation.     

A Spectrophotometric Analysis of Pigments in Apples

Methods of pigment extraction using traditional polar organic solvents (acetone or methanol) were compared to those employing a chloroform–methanol mixture. We found that, for spectrophotometric pigment analysis in the apple peel, the cuticular lipids must be preliminarily extracted from the samples with chloroform and MgO must be added during homogenization to prevent pigment degradation. The traditional extraction did not result in the complete extraction of intact pigments, and such extracts contained a considerable amount of light-absorbing impurities. The application of chloroform–methanol extraction allowed us to markedly reduce the content of such impurities and to increase the accuracy and sensitivity of the measurement of the content of chlorophylls and carotenoids. In addition, this extraction method proved useful for the analysis of phenolic substances (anthocyanins and flavonoids) in the water-methanol fraction of the extracts.