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1.
Previous studies have demonstrated a relationship between Md-ACS1 allelotype and apple fruit softening at ambient temperatures. The present study was undertaken to further examine the influence of this allelotype (-1/1, -1/2 or -2/2) and its interaction with harvest season (early or late) on changes in internal ethylene concentrations (IEC) and fruit softening during cold air storage. This was carried out by describing natural differences found among old apple cultivars/species and modern commercial cultivars. For late maturing cultivars, Md-ACS1-1/1 was firmer at harvest than Md-ACS1-2/2 with the heterozygote intermediate. However harvest firmness showed no differences among for the early season Md-ACS1 allelotypes. The Md-ACS1-2/2 allelotype had a slower rate of postharvest IEC increase and flesh softening compared with Md-ACS1-1/1 and -1/2 allelotypes, and late maturing cultivars had a slower rate of fruit softening than early maturing cultivars, which was independent of postharvest IEC. All three late season allelotypes and early season Md-ACS1-2/2 were firmer after storage than early season Md-ACS1-1/1 and -1/2 allelotypes, reflecting differences in both harvest firmness and softening rates. While cultivar variation in final firmness could be explained partially through Md-ACS1-mediated postharvest ethylene increases and subsequent softening, much more variation was accounted for by their differences in harvest firmness. These results are discussed in relation to strategies for breeding cultivars with superior flesh textures that are maintained during storage.  相似文献   

2.
Blue mold and bitter rot, caused by Penicillium expansum and Colletotrichum gloeosporioides, respectively, are two of the most devastating diseases during and after storage of apple. The present project was conducted to evaluate the level of tolerance to these diseases in apple germplasm, and investigate possible associations with other fruit characteristics such as harvest date, firmness at harvest, softening (loss of firmness during storage) and sun-exposure. Apples were harvested at a maturation stage suitable for storage, inoculated with spore suspensions of P. expansum (127 cultivars) or C. gloeosporioides (70 cultivars), and stored for 6 or 12 weeks for early- and late-maturing cultivars, respectively. Fruit firmness was measured after harvest and after storage, and the difference was used as a measure of fruit softening. Average lesion diameter varied significantly among both early- and late-maturing cultivars. The amount of damage caused by the two diseases was significantly correlated across cultivars. Regression analyses indicated that lesion diameter was positively affected by fruit softening and negatively affected by harvest date and firmness at harvest. Impact of the independent variables was quantified with partial least squares discriminant analysis; approximately 40% of the genetic variation could be explained by these variables with harvest date being the most important. The effect of sun-exposure was analyzed on six bi-colored cultivars but the results were not conclusive. Cultivars that showed relatively small symptoms in spite of being early-maturing and/or only medium firm, may have other traits that are beneficial for storage and could therefore be especially useful in breeding programs.  相似文献   

3.
Heterotic response for total yield among five cultivar-groups of summer squash, Cocozelle, Vegetable Marrow, Zucchini, Crookneck and Straightneck, was studied in two sets of diallel crosses evaluated in two harvest seasons. Each diallel cross included two representatives of each the five cultivar-groups. Griffing and diallel GGE biplot (genotype main effect and interaction) analyses were carried out. The relative importance of the specific combining ability variance on total variance was greater than that reported earlier for intragroup crosses. Highly significant heterosis was manifested only in combinations of Crooknecks or Straightnecks crossed to Cocozelles, Vegetable Marrows or Zucchinis. GGE biplots showed a consistent arrangement where testers of ssp. texana interacted with cultivars of ssp. pepo and vice versa. We propose that the heterotic pattern of texana-pepo crosses could be potentially used to achieve increased yields in hybrids by introgressing one group into another in a manner that would maintain fruit attributes of the cultivar-group. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

4.
The availability of genetic linkage maps enables the detection and analysis of QTLs contributing to quality traits of the genotype. Proton Transfer Reaction Mass Spectrometry (PTR-MS), a relatively novel spectrometric technique, has been applied to measure the headspace composition of the Volatile Organic Compounds (VOCs) emitted by apple fruit genotypes of the progeny ‘Fiesta’ × ‘Discovery’. Fruit samples were characterised by their PTR-MS spectra normalised to total area. QTL analysis for all PTR-MS peaks was carried out and 10 genomic regions associated with the peaks at m/z = 28, 43, 57, 61, 103, 115 and 145 were identified (LOD > 2.5). We show that it is possible to find quantitative trait loci (QTLs) related to PTR-MS characterisation of the headspace composition of single whole apple fruits indicating the presence of a link between molecular characterisation and PTR-MS data. We provide tentative information on the metabolites related to the detected QTLs based on available chemical information. A relation between apple skin colour and peaks related to carbonyl compounds was established. The two authors contributed equally to this work.  相似文献   

5.
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6.
The absorption coefficient μa measured at 670 nm in fruit pulp at harvest by time-resolved reflectance spectroscopy (TRS) has been shown to be a good maturity index for early nectarine cultivars. By including individual fruit maturity as a biological shift factor (BSF) into a kinetic model for softening it is possible to select fruit with different shelf-life potential. The BSF approach combined with TRS measurement and kinetic modeling of firmness was applied to a late maturing nectarine cultivar (‘Morsiani 90’), ripened at 20 °C after harvest or after storage at 0 °C and 4 °C, the latter conditions inducing chilling injury. At harvest the absorption coefficient μa had low values and low variability, indicating advanced maturity, while firmness was similar to that of early cultivars. The softening model took into account these differences, showing parameters similar to those of the early cultivars with the exception of the softening rate which was 2-6 times lower, indicating a slower softening in ‘Morsiani 90’ fruit. Decay of μa at 20 °C was also slower. Softening continued during storage at 4 °C, but not at 0 °C. After storage at 0 °C softening was resumed similarly to non-stored fruit, but with much variability. Fruit stored at 4 °C, which showed chilling injury, had a softening rate at 20 °C significantly higher than that of 0 °C fruit. It is suggested that the same changes in cell wall metabolism which induce the appearance of chilling injury also affect firmness and increase softening rate.  相似文献   

7.
The effects of postharvest application of aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP) on ethylene production and fruit quality, and thus on transportation and shelf-life, were evaluated in melting-flesh peaches. AVG (150 mg L−1) significantly reduced ethylene production, and the effect was enhanced in combination with 1-MCP (1 μL L−1). However, fruit treated with AVG alone softened to untreated control levels 2 d after harvest (DAH). Treatment with 1-MCP significantly reduced the rate of softening until 2 DAH, but the fruit rapidly softened thereafter, and reached untreated control levels by 4 DAH. A combination of AVG and 1-MCP significantly reduced fruit tissue softening throughout ripening. The effect of each chemical on flesh firmness indicated that 1-MCP affected fruit response in the early stages of ripening up to 4 DAH, and AVG significantly reduced softening in the latter stages from 4 to 9 DAH. Peaches treated with AVG and 1-MCP retained their ground color during ripening, but the effect of each chemical on color is unclear. The present study indicates that combined treatment with AVG and 1-MCP significantly delays the ripening of melting-flesh peaches.  相似文献   

8.
Genotype × environment interactions for tea yields   总被引：1，自引：0，他引：1  
Several methods were used to evaluate phenotypic stability in 20 tea (Camellia sinensis) genotypes, many of which are cultivated widely in East Africa. The genotypes were evaluated for annual yields at two sites over a six year period. Data obtained were used to compare methods of analysis of G × E interactions and yield stability in tea. A standard multi-factor analysis of variance test revealed that all first order interactions (genotypes × sites; genotypes × years; sites × years) as well as second order interactions (sites × genotype × years) were significant. Regression analysis was used to assess genotype response to environments. Regression coefficients (bi) obtained ranged from 0.78 to 1.25. Deviations from regression (S2d) were significant (p < 0.05) from 0.0 for all the test genotypes. Analysis for sensitivity to environment change (SE2 i) revealed that the test genotypes differed in their level of sensitivity. The hierarchical cluster analysis method was used to assemble the test genotypes into groups with similar regression coefficients (bi) and mean yield, which proved useful for the identification of high yielding genotypes for breeding purposes as well as for commercial exploitation. Rank correlation between yield and some stability parameters were significant. Mean yield was significantly correlated to bi (r = 0.80***) and SE2 i(0.74***) which is an indication that selection for increased yield in tea would change yield stability by increasing bi and SE2 i leading to development of genotypes that are specifically adapted to environments with optimal growing conditions. Genotypes differed in response to years and sites. As stand age increased, genotype yields generally increased though annual yield fluctuations were more pronounced in some genotypes than others. This response was not consistent across the sites for all genotypes indicating the need to test clones at multiple sites over longer periods of time. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

9.
QTL analysis and mapping of pre-harvest sprouting resistance in Sorghum   总被引：2，自引：0，他引：2  
One of the most important agronomic problems in the production of sorghum [Sorghum bicolor (L.) Moench] in humid climates is pre-harvest sprouting (PHS). A molecular linkage map was developed using 112molecular markers in an F2 mapping population derived from a cross between IS 9530 (high resistance to PHS) and Redland B2 (susceptible to PHS). Two year phenotypic data was obtained. By means of interval mapping analysis, two significant QTL were detected in two different linkage groups with LOD scores of 8.77and 4.39. Each of these two QTL individually explained approximately 53% of the phenotypic variance, but together, in a two-QTL model, they explained 83% of the phenotypic variance with a LOD score of 12.37.These results were corroborated by a one-way ANOVA in which the four flanking markers of the most likely QTL positions displayed highly significant values in theF-test, and significant variation in trait expression was associated with marker genotypic classes. The four markers with highest effect in the one-way ANOVA were also detected in the second year replication of the F2 population, and significant genotype × environment interactions was observed. The putative relationship between PHS resistance in sorghum and the maize Vp1 gene is also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

10.
Use of DNA-based markers can accelerate cultivar development in variable cultivation environments since, in contrast to phenotype, DNA markers are environment-independent. In an effort to elucidate the genetic basis of genotype-by-environment interaction (G × E) for yield of rice (Oryza sativa L.), the associations between 139 AFLP markers and grain yield were determined for rice grown in fresh water (EC of 0.65 dS m−1) and saline conditions (EC of 4–8 dS m−1) with 0 kg ha−1 or 100 kg ha−1 nitrogen fertilizer in the years 2000 and 2001. A population of recombinant inbred lines of rice, developed from an IR29 × Pokkali cross, was used in the study. Both genotype × salinity and genotype × nitrogen level interactions were significant, with the genotype × salinity interaction being stronger. Through multiple regression analysis using a stepwise procedure for selecting markers, 36 markers were detected for grain yield in the four test conditions and of these 28 were detected in only one test condition implying strong environmental specificity for yield QTL expression. However, the fact that eight QTLs were detected in more than one test condition points to the existence of wide-adaptability genes in this cross. Markers with significant associations with yield explained between 37% and 48% of the yield variation in each test condition. Superior genotypes of rice were identified in all four test conditions based on their marker signatures. Furthermore, across N fertilizer regimes, yield predicted from summed additive effects of QTLs were significantly correlated with observed yield in the same year and across years. Thus marker-assisted selection can help breeders overcome the problem of low selection efficiency encountered during phenotypic selection for yield in stress environments.  相似文献   

11.
Fusarium head blight (FHB), caused by Fusarium graminearum and Fusarium culmorum, is a devastating disease in cereals. This study was undertaken to estimate progeny means and variances in each of five winter triticale and winter wheat crosses using unselected F2−derived lines in F4 or F5 generation bulked at harvest of the previous generation. Fifty (triticale) and 95 (wheat) progeny per cross were inoculated in two (triticale) or three (wheat) field environments. FHB rating was assessed on a whole-plot basis. Mean disease severities of the parents ranged from 2.3 to 6.4 in triticale and from 3.1 to 6.5 in wheat on a 1-to-9 scale (1 = symptomless, 9 = 100% infected). The midparent values generally resembled the means of their derived progeny. Significant (P < 0.01) genotypic variance was detected within each cross, but genotype × environment interaction and error variances were also high for both crops. Medium to high entry-mean heritabilities (0.6–0.8) underline the feasibility of selecting F2-derived bulks on a plot basis in several environments. Phenotypic correlation of FHB resistance between generation F2:4 and F2:5 was r = 0.87 (P < 0.01) tested across 150 wheat bulks at two locations. Our estimates of selection gain are encouraging for breeders to improve FHB resistance in triticale and wheat by recurrent selection within adapted materials.  相似文献   

12.
In strawberry, Fragaria × ananassa Duch., fruit, two different endo-β-1,4-glucanase genes, FaEG1 and FaEG3, also named Cel1 and Cel2, are expressed during the softening process that occurs during fruit ripening. It has also been suggested that FaEG3, which contains a putative cellulose-binding domain, could play a key role in fruit development, since previous attempts to down-regulate this gene through transgenesis have been unsuccessful. In this investigation, we obtained transgenic strawberry plants containing an antisense sequence of the FaEG3 gene under the control of the 35S promoter. Ripened fruit from transgenic lines (Acel lines) showed large variation in FaEG3 silencing, but fruit firmness was similar to control fruit in all the lines. Two Acel lines showing almost 95% reductions in FaEG3 mRNA levels were selected for further study. In these lines, FaEG3 down-regulation was high, from 78 to 95%, at all fruit developmental stages, whereas FaEG1 was only slightly suppressed. In spite of the high FaEG3 silencing achieved, EGase activity was not modified in ripe fruit. At the cell wall level, walls from transgenic ripe fruit contained a significantly higher amount of the 4 M KOH fraction, which is enriched in hemicellulosic polymers. The analysis of this fraction by size exclusion chromatography showed that transgenic cell walls contained a smaller amount of higher molecular mass polymers than controls. Altogether, these results indicate that FaEG3 does not play a key role either in fruit development or fruit softening. However, its silencing affects the amount and, in a minor way, the size of hemicellulosic polymers.  相似文献   

13.
Summary The transfer of genes via Agrobacterium to a perennial tree crop such as apple, requires monitoring of the stability of the genes in the target tissues such as the fruit and leaves. If the same genes are required for introgression into a conventional breeding programme, their expression also needs to be stable and their inheritance should follow a normal Mendelian pattern. In the following report we show, for the first time, the stable expression and Mendelian segregation of transgenes in a tree species. We have evidence for a 1:1 segregation of the nos and nptII genes among R1 progeny from a transgenic apple parent. In addition, we present evidence for stable gene expression of both nos and the co-transferred gene nptII in the flesh of apple fruit 7 years after the initial transformation.Abbreviations nos nopaline synthase - nptII neomycin phosphotransferase - ACC 1-aminocyclopropane carboxylic acid - PVP polyvinylpyrrolidone - PCR polymerase chain reaction - EFE ethylene forming enzyme - B.t. Bacillus thuringiensis  相似文献   

14.
The genetics of photoperiod sensitivity, flowering date, fruit size, gender, female fertility, and disease resistance were investigated in progeny between sets of elite F. virginiana selections and F. × ananassa cultivars and selections planted at sites in Michigan, Minnesota and Ontario. Progeny means varied considerably for all the production traits. Most notable were the large fruit and high fertility observed in crosses with High Falls 22 at all three sites, and Montreal River 10 in Ontario and Michigan. Fragaria virginiana ssp. virginiana parents yielded progeny with much larger fruit than F. virginianassp. glauca parents. General combining ability was significant for all traits at all locations, while specific combining ability was significant for only fruit diameter, ovule set and fruit set in Michigan. Overall, the highest number of day-neutral genotypes were detected in Ontario (mean =44%) compared to Minnesota (31%) and Michigan (26%). In progeny populations of day-neutral F. × ananassa × short-day F. virginiana almost all fit the 1:1 ratio expected if day-neutrality is regulated by a single dominant gene; however, only a few families of short-day F. × ananassa ×day-neutral F. virginianacrosses fit a 1:1 ratio. Likewise, in progeny of day-neutral F. virginiana ×day-neutral F × ananassa crosses, only a few of them fit the 3:1 ratio expected if day-neutrality is regulated by a single dominant gene. These data suggest that it should be relatively easy to useF. virginiana germplasm in strawberry cultivar improvement, and that several different sources of day-neutrality may exist in natural populations. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

15.
Summary Six cultivars of lucerne (Medicago sativa L.) were grown in all possible combinations with eight strains of Rhizobium meliloti in order to assess genetic variation in symbiotic nitrogen fixation. Host genotype and Rhizobium genotype effects on nitrogen fixation were respectively 4.8% and 21.0% of total phenotypic variance. Genetic variation due to host cultivar × Rhizobium strain interactions accounted for a further 6.0% of phenotypic variance. The results indicated low heritability of general symbiotic effectiveness in the host with interaction effects being large enough to suggest that plant performance may be unpredictable with populations of R. meliloti in field soils. Joint regression analysis showed that about 50% of the interactive variation could be explained by generalized differences in the sensitivity of cultivars to alterations in the genotype of Rhizobium strains. One cultivar, Siriver, was relatively insentitive to changes in the Rhizobium genotype whilst still maintaining high average yield. The implications of the results for lucerne breeding are discussed.  相似文献   

16.
Summary Approximately 1000 seedlings from 20 combinations crossed in 1979, 1980 and 1981 (Theiler-Hedtrich 1985a) were tested for several characters: fruit set (yield), fruit size, fruit colour, formation of abscission layer and bleeding after fruit removal from fruit stalks, bacterial canker resistance, flowering and harvesting time. From progeny of crosses with Stella as pollinator, 56% (Vittoria × Stella) and 46% (Schüttler × Stella) of the seedlings were self-compatible, of which 14 were high yielding with good fruit size and quality. From the data recorded it can be concluded:fruit set is a recessive character; only 5 to 20% of very good yielding seedlings were obtained in different progeny, even if the parental plants were both very good croppers.Fruit juice and skin colour was in most progenies ‘black’ even if they were from combinations with ‘white’ varieties, e.g., Merton Glory or Schüttler. Only from the combination Schiittler (‘white’) × Stella (‘black’), 50% of the seedlings were ‘white’; Stella therefore is heterozygous for the character of fruit juice and skin colour.Fruit size is evenly distributed in progeny with respect to the fruit size of their parent plants.Abscission layer formation and non-bleeding is a genetically complex character. In combinations where both parent plants formed fruits with complete abscission layers and which were not bleeding after fruit removal from the stalk, this character was inherited only to 50% (Vittoria × Schüttler) or 85% (Vittoria × Frühe von der Weid) in the progeny. For the genetical control of this character further studies are necessary.Bacterial canker susceptibility was evenly distributed in seedlings from all combinations even if the highly resistant cv. Vittoria was used as one parent plant, thereby not confirming the expected results of a higher proportion of resistant seedlings from combinations with Vittoria.Flowering and harvest time of the seedlings from different combinations was within the range of the parent plants. Only in the combination of Vittoria × Stella (mid-to late-ripening season) one seedling out of 99 was found to form ripe fruits two weeks earlier than the parental plants. From the seedlings tested 40 have been chosen for further evaluation or genetical studies.  相似文献   

17.
Summary We report here, for the first time, the stable expression and Mendelian segregation of transgenes in a tree species. So far we have evidence for a 1 : 1 segregation of thenos gene in the R1 of transgenic apple progeny. In addition we present evidence for stable gene expression of bothnos and the co-transferred genenptII in the fruit flesh of the apple fruit some 7 years after the initial transformations.  相似文献   

18.
We estimated genetic and environmental variance components for fruit quality traits (cluster weight, berry weight, soluble solids content, total sugar content, sugar composition, free acid content, total amino acid content, amino acid composition), and a functional trait (gamma-aminobutyric acid (GABA) content) of three commercial tetraploid table grape cultivars (Kyoho, Pione, Suiho) grown in Japan over three successive years. ANOVA showed that the effect of genotype was significant (P < 0.05) for all traits except soluble solids content and total sugar content. The effect of the year was significant for all traits except amino acid composition (γ ratio) and GABA content. The variance of genotype (σ g 2) was highest for γ ratio (63.6%), high in sugar composition (α ratio, 60.3%) and GABA content (58.8%), and negligible for soluble solids content (0.0%) and total sugar content (0.0%). The variance of among years (σ y 2) was very high in soluble solids content (82.8%), high in total sugar content (60.2%) and negligibly small in γ ratio (8.7%) and GABA content (6.4%). Some effects of genotype × year interaction, among vines within genotypes, and vine × year interaction were statistically significant, but these components were negligibly small. Except for soluble solids content and total sugar content, significant varietal differences in the traits were recorded. Variance estimates for each trait provides useful information for optimal yearly repetition to effectively discriminate genetic differences in fruit quality and functional traits for improving future tetraploid table grape breeding programs.  相似文献   

19.
Fruit from the annual replicated yield assessments for the USDA-ARS strawberry (Fragaria ×ananassa Duchesne ex Rozier) breeding program at Beltsville, MD, 2007 and 2008, were evaluated for postharvest decay development after storage at 5 °C. Generalized linear genotype × year mixed model analysis of covariance with overdispersed binomial distribution, logit link function, and Laplace optimization method was used to determine the relationships between postharvest proportion decay and storage period (SP), season’s harvest number (HN), and genotype-specific harvest number through the season; conditioned on the confounding of harvest with SP. To determine if limiting analyses to replicates (plot × harvest combinations) with a minimum number of berries would increase statistical precision, concurrent analyses were conducted using data from replicates with more than: zero, three, and six berries. Limiting data to genotypes for which more than three or more than six berries could be evaluated, resulted in loss of data and reduced statistical power. Within the range of SP observed, 13–19 days, consistency among genotypes of the linear relationship between SP and logit postharvest proportion decay, unless strongly influenced by a confounded harvest effect, indicated all SP in the range tested provided equivalent ability to discern genotypes. The significant genotype × HN interaction effect indicated maximizing the number of harvests was preferable to limiting to a few “informative” harvests. The significant genotype × year interaction effect indicated the decision to release a genotype as a cultivar will demand multiple years of evaluation. Making determinations each year to discard genotypes or use them as parents for postharvest quality was best facilitated by the simple process of calculating arithmetic genotypic means for each harvest date separately, charting the results, and using the charts to visually assess genotypic performance trends across harvests.  相似文献   

20.
Summary  A cross was made between a unique highly branched, early flowering line, U. S. Department of Agriculture (USDA) 846-1 (P1; 7 to 11 lateral branches), and ‘Topmark’ (P2; 2 to 4 lateral branches), a U.S. Western Shipping melon, to produce an array of 119 F3 families. Subsequently, a genetic analysis was conducted at Arlington and Hancock, Wisconsin in 2001 to evaluate the segregating progeny for factors likely involved in yield-formation, including days to anthesis, percentage of plants with early pistillate flowering, primary branch number, fruit number and weight per plant, average weight per fruit, percentage of plants with predominantly crown fruit set, and percentage of plants with early maturing fruit. Although, genotype × environment (G × E) interactions were important for some traits (e.g., fruit number and fruit weight), considerable additive and/or dominance variance was detected for all traits. This research provides critical data associated with highly branched melon germplasm including trait correlations and heritabilies (broad- and narrow-sense ranged between 0.28 and 0.91) that used judiciously will allow the development high yielding melon cultivars with early, basally concentrated fruit suitable for once-over or machine harvesting operations.  相似文献   

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