► Five tomato cultivars and their 10 F1 hybrids were evaluated. ► Heterosis, potence ratio and correlation coefficients were estimated. ► All hybrids had significantly higher fruits number and total ...fruits yield plant. ► The other traits, hybrids exhibited average heterosis in both directions.
Five commercial tomato (Solanum lycopersicum L.) cultivars and their ten F1 hybrids were used in order to detect the general performances and estimation the heterosis percentages, potence ratios, and phenotypic correlation coefficients among all possible pairs of some important tomato's characters. The obtained results reflected a range of significant variability for most of the traits studied. The general performances of the F1 hybrids reflected the presence of various degrees of dominance effects; i.e., partial- to over-dominance for the characters of plant height, number of primary branches per plant, pericarp thickness, fruit firmness, total soluble solids, ascorbic acid content, number of flowers per cluster, number of fruits per plant and total fruits yield per plant. Whereas, some others studied characters; i.e., fruit shape index, locules number per fruit and fruit weight, illustrated the presence of partial- to under-recessiveness; but, with different degrees. All 10 F1 hybrids had significantly higher number of fruits per plant and total fruits yield per plant than their respective mid-parental values, meanwhile for the other traits, hybrids exhibited average heterosis in both directions. The mid-parent heterosis varied from −16.04 to 29.75% for plant height, −5.74 to 20.95 for number of primary branches per plant, −34.72 to 15.18% for fruit shape index, −35.72 to 49.02% for number of locules per fruit, −9.22 to 25.88% for pericarp thickness, −5.02 to 15.21% for fruit firmness, −11.46 to 25.50 for total soluble solids, −1.26 to 15.66% for ascorbic acid content, −9.39 to 22.48% for number of flowers per cluster, 4.37 to 104.69% for number of fruits per plant, −32.78 to 11.29% for average fruit weight, 22.29 to 64.33% for total fruits yield per plant. Significant positive correlation between total fruits yield per plant and each of the number of flowers per cluster, number of fruits per plant and average fruit weight was detected. On the other side, significant negative correlation was observed between number of fruits per plant and fruit weight.
The assessment of nature of gene effect for yield and its contributing traits and detection of epistasis in wheat was studied in five crosses involving seven parents through generation mean analysis. ...Scaling test and joint scaling test were showed significant for almost traits all crosses. Additive gene effects (d) were positively significant for days to maturity and tillers per plant in cross II; for seed per plant in cross IV. Dominance gene effects (h) were highly significant for days to 75% heading in cross II, III and IV; for days to maturity and grains per spike in cross II, for grain yield per plant and grains per spike in cross I. Additive x additive type of gene (i) were positive significant effect for days to 75% heading in cross II, III and IV; for days to maturity in cross II and grains per spike in crosses I, II; for 1000 grain weight in cross II and IV; for grain yield per plant in cross I. Additive x dominance type of gene effect (j) was positive significant for days to 75% heading in cross III; for days to maturity in cross II and III; for plant height in cross III; tillers per plant in cross II; for grain per spike and seed per plant in cross III and grain yield in cross IV. Dominance x dominance effect (l) were positively significant for days to 75% heading, plant height in cross I; for plant height in cross III, IV and V; for tillers per plant in cross II and for grains per spike in cross IV and V; seed per plant, grain yield in cross IV. Therefore, it has been suggested that selection of studied characters based on different gene action of generation mean to be used further crop improvement through ideal breeding programme.
This experiment was implemented in the experimental farm of (Misr hytech seed co. Giza, Egypt) during winter growing seasons 2014 and 2015 to evaluate the inheritance of some cucumber vegetative and ...yielding traits using a complete diallel cross among five inbred lines. The results showed that the mean square of genotypes, parental inbred lines, crosses and parent vs crosses were significant for the studied traits. The hybrids P2xP4 and P2xP5 exhibited a useful heterosis relative to Mp and Bp for the fruit yield per plant and number of leaves per plant. The mean square of general and specific combining ability was significant for the studied traits. The higher GCA/SCA ratio than the unity of the studied traits indicating to the greatest role of the additive gene action in the expression of these traits. The inbred lines P1 and P 2 exhibited significant positive i g ˆ effects in the traits of number of fruit per plant and fruit yield per plant, so these inbred lines could be act as a good combiner for developing high yielding genotypes. The F1 hybrids P1xP3, P2xP4, P2xP5 and P4xP5 as well as the reciprocal hybrids P4xP1, P4xP2, P4xP3 and P5xP3 recorded a significant positive ij S ^ effect but the reciprocal hybrids recorded a significant rij effect. The results revealed to more than one hybrid distinct in some traits that could be utilized in the greenhouse cucumber cultivation and the future breeding programs.
Herbicide tolerance is an important trait that allows effective weed management in wheat crops in dryland farming. Genetic knowledge of metribuzin tolerance in wheat is needed to develop new ...cultivars for the industry. Here, we investigated gene effects for metribuzin tolerance in nine crosses of wheat by partitioning the means and variances of six basic generations from each cross into their genetic components to assess the gene action governing the inheritance of this trait. Metribuzin tolerance was measured by a visual senescence score 21 days after treatment. The wheat 90 K iSelect SNP genotyping assay was used to identify the distribution of alleles at SNP sites in tolerant and susceptible groups.
The scaling and joint-scaling tests indicated that the inheritance of metribuzin tolerance in wheat was adequately described by the additive-dominance model, with additive gene action the most significant factor for tolerance. The potence ratio for all the crosses ranged between - 1 and + 1 for senescence under metribuzin-treated conditions indicating a semi-dominant gene action in the inheritance of metribuzin tolerance in wheat. The number of segregating genes governing metribuzin tolerance was estimated between 3 and 15. The consistent high heritability range (0.82 to 0.92) in F
generations of Chuan Mai 25 (tolerant) × Ritchie (susceptible) cross indicated a significant contribution of additive genetic effects to metribuzin tolerance in wheat. Several genes related to photosynthesis (e.g. photosynthesis system II assembly factor YCF48), metabolic detoxification of xenobiotics and cell growth and development (cytochrome P450, glutathione S-transferase, glycosyltransferase, ATP-binding cassette transporters and glutathione peroxidase) were identified on different chromosomes (2A, 2D, 3B, 4A, 4B, 7A, 7B, 7D) governing metribuzin tolerance.
The simple additive-dominance gene effects for metribuzin tolerance will help breeders to select tolerant lines in early generations and the identified genes may guide the development of functional markers for metribuzin tolerance.
The present investigation was undertaken in F
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population of 48 crosses, developed by crossing 16 lines (8 gynoecious) and 3 testers during the year 2011. All the parental lines and their F
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...hybrids were evaluated in randomised complete block design for yield and its contributing traits during the year 2012. Experimental results revealed that parental lines LC-1-1, CGN-20953, CGN-19533, Gyne-5, LC-15-5 and testers Japanese Long Green and K-75 were found superior on the basis of mean performance and general combining ability effects. The cross combinations LC-1-1 × K-75 (monoecious), CGN-19533 × K-75 (gynoecious), CGN-20953 × Poinsette (gynoecious), Gyne-5 × K-75 (gynoecious) and LC-3-3 × Poinsette (monoecious) excelled based on per se performance, specific combining ability and heterosis studies. Further, performance of top 10 heterotic hybrids illustrated the presence over dominance effects in all the crosses except in one cross, where no dominance was observed. Gene action studies indicated that non-additive gene action governed all the traits under study, suggesting the importance of heterosis breeding for the development of high yielding stable parthenocarpic gynoecious hybrids in cucumber.
We prove that for each positive integer k, all irreducible k-potent ray pattern classes allow k-potence. We construct all irreducible real (complex) k-potent matrices in an irreducible sign (ray) ...k-potent sign (ray) pattern class. For a given reducible sign (ray) pattern that is sign (ray) k-potent for some positive integer k, we determine necessary conditions for that pattern to allow k-potence. This generalizes recent work by Lee and Park (2015) 2 who determined necessary conditions for a sign idempotent sign pattern to allow idempotence, and who showed that every irreducible, sign k-potent sign pattern must allow k-potence.
Compared with understanding of biological shape and form, knowledge is sparse regarding what regulates growth and body size of a species. For example, the genetic and physiological causes of ...heterosis (hybrid vigor) have remained elusive for nearly a century. Here, we investigate gene-expression patterns underlying growth heterosis in the Pacific oyster (Crassostrea gigas) in two partially inbred (f = 0.375) and two hybrid larval populations produced by a reciprocal cross between the two inbred families. We cloned cDNA and generated 4.5 M sequence tags with massively parallel signature sequencing. The sequences contain 23,274 distinct signatures that are expressed at statistically nonzero levels and show a highly positively skewed distribution with median and modal counts of 9.25 million and 3 transcripts per million, respectively. For nearly half of these signatures, expression level depends on genotype and is predominantly nonadditive (hybrids deviate from the inbred average). Statistical contrasts suggest almost equal to350 candidate genes for growth heterosis that exhibit concordant nonadditive expression in reciprocal hybrids; this represents only almost equal to1.5% of the >20,000 transcripts. Patterns of gene expression, which include dominance for low expression and even underdominance of expression, are more complex than predicted from classical dominant or overdominant explanations of heterosis. Preliminary identification of ribosomal proteins among candidate genes supports the suggestion from previous studies that efficiency of protein metabolism plays a role in growth heterosis.
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