Search

Fruit morphology is one of the most important traits in cucumber because it directly affects its commercial value. The cucumber line CS-PMR1 is a promising breeding material for improving disease resistance, but its fruit morphology is not ideal for the Japanese market, and this hampers breeding. We used recombinant inbred lines derived from a cross between CS-PMR1 and the Japanese cultivar ‘Santou’ for genetic analysis of fruit morphological traits. Fruit shape variation was evaluated in detail by means of image analysis, and quantitative trait locus (QTL) analyses were performed by composite interval mapping or interval mapping with a nonparametric model. We detected 41 QTLs: 5 for length, 6 for diameter, 5 for the ratio of length to diameter, 4 for the ratio of placenta diameter to fruit diameter, 16 for principal component scores of elliptic Fourier descriptors related to fruit shape, 2 for wart size and 3 for wart density. Some QTLs were detected in the same chromosomal regions at different fruit stages and for different morphological traits. In particular, several QTLs with large effects on fruit size were located in nearly the same regions as genes for resistance to powdery mildew and downy mildew, indicating that the linkage between fruit shape and the resistance genes is likely to limit breeding efficiency. The results of this study will contribute to the development of informative DNA markers tightly linked to genes for requisite fruit morphological traits, which are urgently required for efficient breeding of new cultivars. [ABSTRACT FROM AUTHOR]

The goal of this study was to estimate the single and joint effect of the basal region of chromosome 2 and centromeric region of chromosome 8 on morphological and fruit quality traits in tomato ( Solanum lycopersicum). The analysis was performed in a population derived from a cross between Rio Grande of S. lycopersicum and LA1589 of S. pimpinellifolium that segregates for both genomic regions. Four major QTLs were found on chromosome 2 and three on chromosome 8, all of them related with morphological traits. QTLs for fruit shape index, proximal fruit end angle and distal fruit end protrusion showed epistatic interaction. Both genomic regions ( fs2.1 and fs8.1) explained 62, 47 and 46 % of the phenotypic variability for fruit shape index, proximal fruit end angle and distal fruit end protrusion respectively. Minor QTLs were detected for other morphological and quality traits such as color, pH and fruit shelf life on chromosomes 2 and 8. Only single genomic region effects were found for quality trait. On the other hand, fs2.1 and fs8.1 regions control several fruit morphology attributes following a digenic linear additive model with epistatic interactions. [ABSTRACT FROM AUTHOR]

Fruit traits, such as shape, size, sugar concentration, and β-carotene concentration affect fruit quality in melon. Extensive genetic diversity for these traits can be exploited for breeding purposes. In this study, an F mapping population was constructed using an orange fleshed cantaloupe-type melon and an exotic green fleshed 'snake melon' to identify quantitative trait loci (QTL) associated with fruit quality and fruit morphological traits. A total of 31 QTLs were identified, of which 23 corroborated previously reported QTLs. A small segment of LG8 explained most of the phenotypic variation for yield. We mapped eight new QTLs for fruit shape, total fruit weight per plant, soluble solids concentration, flesh color, ovary shape and seed cell diameter, and a locus for chlorosis in this study. Soluble solids concentration did not have significant association with average fruit weight and fruit width, suggesting that manipulation of fruit morphology is possible in melon without considerably affecting fruit sweetness. A significant positive association between fruit shape and ovary shape indicated that fruit shape was determined during preanthesis. Our results indicate that natural variation for internal and external melon fruit traits can be further explored by performing QTL analysis of populations derived from crosses between previously unexplored botanical groups. [ABSTRACT FROM AUTHOR]

Classification and characterization of the shape of plant organs are important tools for plant biologists, breeders and growers. Here we use boundary measurements, i.e. contour morphometric data, of scanned tomato fruits in conjunction with elliptic Fourier shape modeling and Bayesian classification techniques to find the optimum number of shape categories. Our findings show that there are nine computationally and visually distinct tomato shape categories: ellipsoid, flat, heart, long, long rectangular, rectangular, round, obovoid, and oxheart. Analyses of fruits from a diverse set of tomato accessions demonstrate that some varieties carry fruits that conform to predominantly one shape category while others carry fruits that conform to multiple shape categories. In particular the categories oxheart and long rectangular feature fruit that tend to equivalently fit several categories of shape, while the flat and obovoid categories contain fruit that consistently conform exclusively to a single category. The findings show that elliptic Fourier shape modeling and Bayesian classification provide an excellent tool for further in depth analyses of fruit shape variation that may occur across varieties and/or result from growth under different environmental conditions. [ABSTRACT FROM AUTHOR]

The character of flat versus round fruit shape is controlled by a single gene ( S/ s) on chromosome 6 in peach [ Prunus persica (L.) Batsch], with the flat fruit phenotype produced by the S/s heterozygous genotype. We used 16 simple sequence repeat (SSR) markers at the S/ s region and physically mapped them in the peach sequence. Seven were mapped in the new F1 population from a cross between the two flat fruit cultivars 'UFO-3' and 'Sweet Cap' that segregated for the S/ s gene. Fourteen of the SSRs were mapped in the Prunus reference map (T×E), of which seven had already been mapped and seven were added within this work. Our results confirmed the position of S/ s on the distal part of chromosome 6. Thirteen of the initial 16 markers were also studied in a collection of flat (66) and round (39) cultivars, where some of the alleles were associated to the character and one of them, the 131 bp allele of marker UDP98-412, predicted in 98.4 % of the cases the flat shape. This allele was highly predictive of the flat fruit character in an additional collection of 100 cultivars, and is an useful tool for marker-assisted selection of flat peaches and nectarines, a trait that is becoming of increasing interest in breeding programs as consumption of these fruits is growing in the European market. [ABSTRACT FROM AUTHOR]

Agronomic and fruit quality traits were evaluated and compared for three consecutive years on 1,111 seedlings coming from 15 peach and nectarine breeding crosses, grown under a Mediterranean climate. Significant differences among and within the different progenies were found for most of the traits analyzed. The breeding population segregated for several Mendelian characters such as peach or nectarine fruit, round or flat fruit, yellow or white flesh and freestone or clingstone. In addition, aborting fruit and flat fruit trees were found in our progeny, and our data seem to support multi-allelic control of both flat shape and aborting fruit. The variation within the progenies of some traits such as blooming and harvesting date, yield, fruit weight and SSC was continuous, suggesting a polygenic inheritance. Relationships between qualitative pomological traits and these agronomic and fruit quality parameters were also found. Valuable correlations among agronomic and fruit quality parameters were found, although coefficients of variation depending on the progeny should be considered. In addition, principal component analysis (PCA) revealed several relationships among quality traits in the evaluated progenies. Based on this evaluation, 26 outstanding genotypes were pre-selected from the initial breeding population for further studies. [ABSTRACT FROM AUTHOR]

Fruit quality traits were studied in 12 exotic accessions and their hybrids with a “Piel de Sapo” inodorus melon cultivar. The genetic relationships among these genotypes were assessed with 16 microsatellite markers, which agreed with the classification of Cucumis callosus, C. pubescens and C. trigonus as accessions within C. melo. There were very large differences between all the exotic accessions and “Piel de Sapo” genotype for fruit traits. When the hybrids were analysed, three different situations regarding mid parent heterosis were found, depending on the trait: no heterosis (soluble solid concentration), highly variable, from negative to positive (fruit weight and fruit diameter) and general positive heterosis (ovary shape, fruit length and fruit shape). Best parent heterosis for fruit shape was also common among hybrids. A highly significant correlation ( r = 0.81) was detected between fruit shape and fruit length heterosis, suggesting that fruit shape heterosis is caused mainly by the enlargement of the fruit longitudinally. A highly significant correlation ( r = 0.84) between heterosis for fruit shape and genetic distance, as estimated with microsatellites, was also found. These results, together with the previously reported observation that melon fruit shape is polygenic and highly heritable, makes the genetics of melon fruit shape a suitable system for dissecting the genetic and molecular basis of heterosis. [ABSTRACT FROM AUTHOR]

A measurement system, which consisted of a CCD laser displacement sensor and two pulse stages, was constructed to obtain three-dimensional (3-D) surface data of Citrus fruit. Fruits of 58 species of three specimens each were measured. By expanding the data measured in a series of spherical harmonic functions, a set of expansion coefficients to characterize the object shape was obtained. The data was normalized to make the coefficients be independent of the x- and y-coordinates of the object. To summarize the information about shape contained in the62 coefficients, a principal component analysis of the standardized spherical harmonic coefficients of each fruit was made. The contribution of each of the first seven principal components was found to exceed that of a single variable. The first three principal components had a cumulative contribution of 0.823.Analysis of variance showed that the variance due to between-species as tested against the variance due to within-species was significant for the 1st,2nd, 3rd, 4th, 7thcomponent score and the volume. A scatter diagram of the 1st and 2nd principal components failed to group the species studied. [ABSTRACT FROM AUTHOR]

Heritabilities for each of three different height and width ratios describing fruit shape were estimated from measurements on a population of seedlings comprising 17 families of European and Asian pear parentage in the Hort Research pear cultivar breeding programme. In families with European cultivars as parents, the pyriform curvature in the upper, or stem end, half of the fruit was also quantified and heritabilities estimated. Heritabilities were computed using parent-offspring regression and from consideration of the variance components. Heritabilities estimated from parent-offspring regression were generally high and higher than those estimated from variance component analysis, although within the limits of error. Heritability estimates for the height: maximum width ratio were > 0.5 by both methods of estimation indicating that fairly rapid genetic gain could be expected. [ABSTRACT FROM AUTHOR]

Apples from 1253 genotypes representing 82 open pollinated families planted at three sites were cut along the stem-calyx axis at the widest point to analyse fruit shape. An image analysis program was used to extract calliper measurements of the fruit outline and calculated Fourier descriptors for each fruit outline. Five independent shape traits were identified from a principal component analysis of the Fourier descriptors. The shape traits and the proportion of the total phenotypic variation they accounted for were: fruit aspect (76.8%), asymmetric-crown (7.8%), fruit conicity (6.0%), asymmetric-sides (4.3%), and fruit squareness (2.0%). Genetic and residual variance components were estimated with data from two sites using restricted maximum-likelihood techniques to select genetically-inherited apple shape traits. Combined sites heritability was estimated to be 0.79 for aspect, 0.38 for conicity and 0.35 for squareness. Multiple regression between calliper measurements and aspect, conicity, and squareness traits showed firstly that aspect was best predicted by fruit length/width ratio (R2 = 0.97), secondly conicity could be described by both the distance of the maximum width from the base of the fruit/fruit length ratio and the calyx basin width/fruit width ratio (R2 =0.44), and finally squareness was best described by ratio of the product of calyx basin width and distance of the maximum width from the calyx end of the fruit by the product of fruit length and fruit width(R2 = 0.19). A chart based on the aspect, conicity and squareness principal component values was drawn to allow visual assessment of shape. [ABSTRACT FROM AUTHOR]

Heterosis and inbreeding depression for fruit yield has been reported for pickling cucumber ( Cucumis sativus L.). However, cucumber inbreds often perform as well as hybrids, and there is little inbreeding depression. The objectives of this study were to reexamine the amount of heterosis and inbreeding depression for fruit yield and yield components in pickling cucumber, and to determine the relationship between yield components and yield for heterosis. Two pickling cucumber inbreds (M 12, M 20) and inbreds from four open-pollinated monoecious cultivars (‘Addis’, ‘Clinton’, ‘Wisconsin SMR 18’, ‘Tiny Dill’) were hybridized to form four F1 hybrids (‘Addis’ × M 20, ‘Addis’ × ‘Wis. SMR 18’, ‘Clinton’ × M 12, M 20 × ‘Tiny Dill’). F1 hybrids were then self-pollinated or backcrossed to generate F2, BC1A, and BC1B progeny. Thirty plants of each generation within each hybrid family were grown in plots 3.1 m long with four replications in each of two seasons. Data were collected from once-over harvest for vegetative, reproductive, yield, and fruit quality traits. Heterosis and inbreeding depression for fruit yield and yield components were not observed in three of the hybrids. Only ‘Addis’ × ‘Wis. SMR 18’ exhibited high-parent heterosis and inbreeding depression for total, marketable, and early fruit weight. For ‘Addis’ × ‘Wis. SMR 18’, heterosis for fruit yield was associated with a decreased correlation between percentage of fruit set and fruit weight, an increased negative correlation between percentage of fruit set and both the number of branches per plant and the percentage of pistillate nodes, and an increased negative correlation between the number of nodes per branch and total fruit weight. Inbreeding depression was associated with a weakening of the strong negative correlations between percentage of fruit set and the number of branches per plant, and between the number of nodes per branch and total fruit weight. Those correlations were associated with high-parent heterosis and inbreeding depression only for one cross, and do not necessarily apply to future crosses in which heterosis may be observed for yield. We did not observe the heterosis or inbreeding depression for yield in cucumber in most of the crosses as was reported by Ghaderi & Lower (1979a; 1979c). [ABSTRACT FROM AUTHOR]