Phenotypic and fine genetic characterization of the D locus controlling fruit acidity in peach

Background  

Acidity is an essential component of the organoleptic quality of fleshy fruits. However, in these fruits, the physiological and molecular mechanisms that control fruit acidity remain unclear. In peach the D locus controls fruit acidity; low-acidity is determined by the dominant allele. Using a peach progeny of 208 F₂ trees, the D locus was mapped to the proximal end of linkage group 5 and co-localized with major QTLs involved in the control of fruit pH, titratable acidity and organic acid concentration and small QTLs for sugar concentration. To investigate the molecular basis of fruit acidity in peach we initiated the map-based cloning of the D locus.     

A natural mutation-led truncation in one of the two aluminum-activated malate transporter-like genes at the Ma locus is associated with low fruit acidity in apple

Acidity levels greatly affect the taste and flavor of fruit, and consequently its market value. In mature apple fruit, malic acid is the predominant organic acid. Several studies have confirmed that the major quantitative trait locus Ma largely controls the variation of fruit acidity levels. The Ma locus has recently been defined in a region of 150 kb that contains 44 predicted genes on chromosome 16 in the Golden Delicious genome. In this study, we identified two aluminum-activated malate transporter-like genes, designated Ma1 and Ma2, as strong candidates of Ma by narrowing down the Ma locus to 65-82 kb containing 12-19 predicted genes depending on the haplotypes. The Ma haplotypes were determined by sequencing two bacterial artificial chromosome clones from G.41 (an apple rootstock of genotype Mama) that cover the two distinct haplotypes at the Ma locus. Gene expression profiling in 18 apple germplasm accessions suggested that Ma1 is the major determinant at the Ma locus controlling fruit acidity as Ma1 is expressed at a much higher level than Ma2 and the Ma1 expression is significantly correlated with fruit titratable acidity (R (2) = 0.4543, P = 0.0021). In the coding sequences of low acidity alleles of Ma1 and Ma2, sequence variations at the amino acid level between Golden Delicious and G.41 were not detected. But the alleles for high acidity vary considerably between the two genotypes. The low acidity allele of Ma1, Ma1-1455A, is mainly characterized by a mutation at base 1455 in the open reading frame. The mutation leads to a premature stop codon that truncates the carboxyl terminus of Ma1-1455A by 84 amino acids compared with Ma1-1455G. A survey of 29 apple germplasm accessions using marker CAPS(1455) that targets the SNP(1455) in Ma1 showed that the CAPS(1455A) allele was associated completely with high pH and highly with low titratable acidity, suggesting that the natural mutation-led truncation is most likely responsible for the abolished function of Ma for low pH or high acidity in apple.     

Mapping quantitative physiological traits in apple (Malus × domestica Borkh.)

Efficient breeding and selection of high-quality apple cultivars requires knowledge and understanding of the underlying genetics. The availability of genetic linkage maps constructed with molecular markers enables the detection and analysis of major genes and quantitative trait loci contributing to the quality traits of a genotype. A segregating population of the cross between the apple varieties `Fiesta' (syn. `Red Pippin') and `Discovery' has been observed over three years at three different sites in Switzerland and data on growth habit, blooming behaviour, juvenile period and fruit quality has been recorded. QTL analyses were performed, based on a genetic linkage map consisting of 804 molecular markers and covering all 17 apple chromosomes. With the maximum likelihood based interval mapping method, the investigated complex traits could be dissected into a number of QTLs affecting the observed characters. Genomic regions participating in the genetic control of stem diameter, plant height increment, leaf size, blooming time, blooming intensity, juvenile phase length, time of fruit maturity, number of fruit, fruit size and weight, fruit flesh firmness, sugar content and fruit acidity were identified and compared with previously mapped QTLs in apple. Although `Discovery' fruit displayed a higher acid content, both acidity QTLs were attributed to the sweeter parent `Fiesta'. This indicated homozygosity at the acidity loci in `Discovery' preventing their detection in the progeny due to the lack of segregation.     

Fruit quality attributes of blackberry (<Emphasis Type="Italic">Rubus sanctus</Emphasis>) mutants obtained by <Superscript>60</Superscript>Co gamma irradiation

Blackberry mutants were induced by the irradiation of blackberry shoots with 5 kilo radians of cobalt (⁶⁰Co) gamma irradiation. Seven mutant plants demonstrating improved plant growth properties were selected for evaluation of the fruit quality characteristics, such as size, shape, color, firmness, soluble solids content, juice acidity, nutritive value (e.g. ascorbic acid) and overall fruit flavor. The organoleptic properties, including texture, firmness, flavor, sweetness, acidity, color, and overall fruit flavor, were evaluated by a consumer panel. The results indicated that irradiation induced changes in some of the quality parameters of blackberry fruits, as well as increased the fruit shelf-life.     

Estimation of genetic parameters and prediction of breeding values for apple fruit-quality traits using pedigreed plant material in Europe

Genetic parameters for apple (Malus x domestica) fruit external traits (fruit size, ground colour, proportion of over colour and attractiveness) and sensory traits (firmness, crispness, texture, juiciness, flavour, sugar, acidity and global taste) were estimated using 2,207 pedigreed genotypes from breeding programmes in six European countries. Data were scored for 3 years and four periods during storage. Analyses were performed with a restricted maximum likelihood method using VCE 5.1.2 software. Heritability estimates ranged from medium to high for instrumental traits. Genetic correlations between firmness and sugar were medium and low between firmness and acidity. Sensory traits showed low to high heritability, acidity and flavour being, respectively, the most and the less heritable. Global taste was strongly correlated with texture, juiciness, and flavour and relatively less correlated with crispness and acidity. Sensory sugar and acidity showed highly negative correlations whereas their instrumental measurements showed low and increasing positive correlations from harvest to 4 months post-harvest. Sugar exhibited a higher sensory/instrumental divergence. Conversely, instrumental and sensory firmness were highly correlated. Fruit external characteristics had medium heritability. Fruit attractiveness had highest and lowest correlations with fruit size and ground colour, respectively. Best linear unbiased predictors of breeding values were computed for all genotypes with the software PEST. The results were analysed with regard to the dynamic and the reliability of genetic parameters according to the scoring dates. Original issues of the study and the importance of the obtained results for efficient designs of further apple fruit quality breeding programmes were discussed.     

Effect of pre-storage treatments on mango fruit ripening

The effectiveness of pre-storage treatments of nitrogen (low oxygen), heat and ethanol and acetaldehyde vapours were examined for their potential for improving mango storage. Mature green mango fruit (Mangifera indica L. cv. Keitt) were treated with low oxygen (< 3% oxygen, 97% nitrogen) for 72 h, acetaldehyde (0.12%) and ethanol (1%) vapours for 24 h or heat (38 ± 2°C) for 48 h prior to storage at 14°C. The nitrogen and ethanol treatments induced substantial levels of acetaldehyde and ethanol in the fruit. Initially the firmness of the nitrogen treated fruit remained higher than the control although later in storage this effect was lost. Differences in ripening were reflected in the total soluble solids and acidity levels, nitrogen maintaining a higher acidity and lower total soluble solids (less mature) whereas the heat treated fruit had lower acidity and higher total soluble solids (more mature). Ethanol and acetaldehyde treatments showed no effect. The use of a pre-storage treatment of nitrogen therefore had a beneficial effect on retarding ripening, although as storage progressed this effect was lost.     

Genome-wide assessment of population structure and genetic diversity of Eucalyptus urophylla based on a multi-species single-nucleotide polymorphism chip analysis

Tree Genetics & Genomes - The fruit of American cranberry (Vaccinium macrocarpon Ait.) is known for its tart, acidic taste. Although some acidity is required for expressing fruit flavor, the...     

臭氧水对荔枝采后若干生理生化指标的影响

用不同浓度臭氧水对荔枝果实进行采后处理,测定其花色素苷、类黄酮、可滴定酸和糖含量以及多酚氧化酶和过氧化物酶活性。结果显示,处理后荔枝果皮中花色素苷、类黄酮含量下降速度低于对照,PPO活性低于对照,POD活性高于对照,而果汁中可滴定酸及糖含量与对照相比无显著变化。表明一定浓度臭氧水对荔枝果实保色护色有一定效果,并有防褐变作用。     

Genetic characterization of the Ma locus with pH and titratable acidity in apple

Apple fruit flavor is greatly affected by the level of malic acid, which is the major organic acid in mature apple fruit. To understand the genetic and molecular basis of apple fruit acidity, fruit juice pH and/or titratable acidity (TA) were measured in two half-sib populations GMAL 4595 [Royal Gala?×?PI (Plant Introduction) 613988] and GMAL 4590 (Royal Gala?×?PI 613971) of 438 trees in total. The maternal parent Royal Gala is a commercial variety and the paternal parents are two M. sieversii (the progenitor species of domestic apple) elite accessions. The low-acid trait segregates recessively and the overall acidity variations in the two populations were primarily controlled by the Ma (malic acid) locus, a major gene discovered in the 1950s (Nybom in Hereditas 45:332?C350, 1959) and later mapped to linkage group 16 (Maliepaard et al. in Theor Appl Genet 97:60?C73, 1998). The allele Ma has a strong additive effect in increasing fruit acidity and is incompletely dominant over ma. QTL (quantitative trait locus) analyses in GMAL 4595 mapped the major QTL Ma in both Royal Gala and PI 613988, the effects of which explained 17.0?C42.3% of the variation in fruit pH and TA. In addition, two minor QTL, tentatively designated M2 and M3, were also detected for fruit acidity, with M2 on linkage group 6 of Royal Gala and M3 on linkage group 1 of PI 613988. By exploring the genome sequences of apple, eight new simple sequence repeat markers tightly linked to Ma were developed, leading to construction of a fine genetic map of the Ma locus that defines it to a physical region no larger than 150?kb in the Golden Delicious genome.     

Effect of postharvest salicylic acid treatment on fungal decay and some postharvest quality factors of kiwi fruit

The effect of salicylic acid (SA) treatment at different concentrations on fungal decay and some quality factors of kiwi fruit (Actinidia deliciosa var. Hayward) in postharvest conditions were studied. Results experiment showed that SA at all applied concentrations inhibited grey mould growth. The SA application significantly decreased weight loss percentage and increased life storage fruits. Also, SA positively affected on postharvest quality factors including total soluble solids (TSS), titratable acidity (TA), antioxidant, ascorbic acid and pH value. It was observed that treated fruits with SA at concentration 5?mM had the highest TSS, TA, ascorbic acid and antioxidant content and it had the lowest decay and acidity. Thus, these results showed that SA has strong impact on postharvest decay and fruit quality of kiwi fruit.     

Genetic architecture of apple fruit quality traits following storage and implications for genetic improvement

Accurate prediction of genetic potential and response to selection in breeding requires knowledge of genetic parameters for important selection traits. Data from breeding trials can be used to obtain estimates of these parameters so that predictions are directly relevant to the improvement program. Here, a factor allocation diagram was developed to describe the sampling design used to assess the quality of fresh and post-storage (2 months) fruit from advanced selection trial in an apple breeding program from which models for analyses were developed. Genetic variation was the largest source of variation for the fruit size, red colour type, proportion of red skin colour and lenticels, and instrumentally assessed fruit diameter, mass, puncture force and titratable acidity. In contrast, residual variation was the largest for fruit shape, juiciness, sweetness, aromatic flavour, eating and overall quality, and instrumental crispness. Genetic effects for traits were generally stable over fixed effects, except for a significant interaction with storage duration for firmness. Genetic correlations among traits were generally weak except between fruit mass (and diameter) and sensory size (0.98), titratable acidity and sensory acidity (0.97), puncture force and sensory firmness (0.96–0.90), crispness and juiciness (0.87), sweetness and aromatic flavour (0.84) and instrumental and sensory crispness (0.75). Predictions of the performance for seven commercial cultivars are presented. This study suggests that the Washington State apple production area can be treated as a single target environment and sufficient diversity exists to generate new elite cultivars. In addition, options for evaluating the efficiency of apple breeding are discussed.     

Comparative analysis of quality and nutritional traits from Lonicera caerulea (Honeyberry) cultivars and other berries grown in Scotland

Lonicera caeruleabrix is a perennial shrub native to North America, Europe and Asia. It produces dark blue berries known as honeyberries or haskap berries which are produced commercially in several territories including Canada, Japan, Russia and Poland. Plants are suited to UK environments, but it is yet to be widely commercially developed in the UK. In the present work, quality and nutritional traits of six honeyberry cultivars grown in Scotland were compared with other commonly grown berry fruits (strawberry, raspberry, blueberry, blackberry, blackcurrant) to aid the identification of environmentally stable, high-quality honeyberry cultivars suitable for UK cultivation. Differences were observed in fruit quality variables (soluble solids, titratable acidity and Brix/acid ratios) between honeyberry cultivars. Three of six cultivars examined exhibited notable variation in soluble solids dependent on harvest year with ‘Aurora’ and ‘Strawberry Sensation’ having consistently high ^oBrix values. Titratable acidity exhibited cultivar differences and there was limited variation over harvest years. ‘Aurora’ exhibited consistently high ^oBrix/titratable acidity ratio reflected by high glucose and fructose content. Honeyberry fruit had good nutritional profile relative to other soft fruits with higher polyphenol and anthocyanin content than strawberry, blueberry, blackberry and raspberry, manifested in greater antioxidant capacity. The major anthocyanins in aqueous honeyberry fruit extracts were cyanidin, pelargonidin and peonidin glycosides. These findings indicate that L. caerulea represents a crop suitable for UK cultivation capable of producing high quality fruit with a valuable nutritional profile relative to other soft fruits. Cultivars exhibit significant differences in fruit quality and nutritional profile as well as harvest consistency and growers should consider this when establishing new plantations.     

The effect of different irrigation treatments on yield and quality of Verna lemon

Verna lemon trees were irrigated by six different treatments: five flood and one drip. Soil and plant water status, yields and fruit quality were measured. The drip-irrigated treatment gave higher yield and fruit size. The levels of soluble solids, acidity and sugars in the lemon juice decreased in the treatments that used most water. This is explained by a dilution effect. An erratum to this article is available at .     

Co-mapping studies of QTLs for fruit acidity and candidate genes of organic acid metabolism and proton transport in sweet melon (Cucumis melo L.)

Sweet melon cultivars contain a low level of organic acids and, therefore, the quality and flavor of sweet melon fruit is determined almost exclusively by fruit sugar content. However, genetic variability for fruit acid levels in the Cucumis melo species exists and sour fruit accessions are characterized by acidic fruit pH of <5, compared to the sweet cultivars that are generally characterized by mature fruit pH values of >6. In this paper, we report results from a mapping population based on recombinant inbred lines (RILs) derived from the cross between the non-sour 'Dulce' variety and the sour PI 414323 accession. Results show that a single major QTL for pH co-localizes with major QTLs for the two predominant organic acids in melon fruit, citric and malic, together with an additional metabolite which we identified as uridine. While the acidic recombinants were characterized by higher citric and malic acid levels, the non-acidic recombinants had a higher uridine content than did the acidic recombinants. Additional minor QTLs for pH, citric acid and malic acid were also identified and for these the increased acidity was unexpectedly contributed by the non-sour parent. To test for co-localization of these QTLs with genes encoding organic acid metabolism and transport, we mapped the genes encoding structural enzymes and proteins involved in organic acid metabolism, transport and vacuolar H+ pumps. None of these genes co-localized with the major pH QTL, indicating that the gene determining melon fruit pH is not one of the candidate genes encoding this primary metabolic pathway. Linked markers were tested in two additional inter-varietal populations and shown to be linked to the pH trait. The presence of the same QTL in such diverse segregating populations suggests that the trait is determined throughout the species by variability in the same gene and is indicative of a major role of the evolution of this gene in determining the important domestication trait of fruit acidity within the species.     

Mechanisms involved in the gastro-protective effect of STW 5 (Iberogast®) and its components against ulcers and rebound acidity

The protective effect of a commercial preparation (STW 5, Iberogast^®), containing the extracts of bitter candy tuft, lemon balm leaf, chamomile flower, caraway fruit, peppermint leaf, liquorice root, Angelica root, milk thistle fruit and greater celandine herb, against the development of gastric ulcers was previously reported in an earlier publication (Khayyal et al., 2001). All extracts produced a dose dependent anti-ulcerogenic effect associated with a reduced acid output, an increased mucin secretion, an increase in prostaglandin E₂ release and a decrease in leukotrienes. The effect on pepsin content was not uniform and did not seem to bear a relationship with the anti-ulcerogenic activity. The best effects were observed with the combined formulation, STW 5. Furthermore, the effect of the latter in protecting against the development of rebound gastric acidity was examined experimentally in rats and compared with the effect of some commercial antacid preparations (Rennie^®, Talcid^® and Maaloxan^®). A model of testing rebound acidity was developed by inducing a marginal increase in gastric acidity through the administration of indomethacin, in such a way that it could be easily neutralized, allowing any eventual secondary increase in acidity to be measured within a few hours of administration. In addition, the serum gastrin level was measured after drug treatment to establish any correlation between it and any rebound acidity. The results obtained demonstrated that STW 5 did not only lower the gastric acidity as effectively as the commercial antacid, but it was more effective in inhibiting the secondary hyperacidity. Moreover, STW 5 was capable of inhibiting the serum gastrin level in rats, an effect which ran parallel to its lowering effect on gastric acid production.     

Polygalacturonase activity and variation in ripening of papaya fruit with tissue depth and heat treatment

Effects of tissue position (viz. outer vs inner mesocarp) and heat treatment (48°C, 20 min) on variations in polygalacturonase (EC 3.2.1.15 and EC 3.2.1.67) activity and ripening of fruits of Carica papaya L. cv. Backcross Solo were investigated. Polygalacturonase activity increased during ripening concomitantly with an increase in tissue softness and soluble polyuronide level. Throughout ripening, inner mesocarp tissue was softer and contained higher polygalacturonase activity than outer mesocarp tissue. Titratable acidity as well as ß-galactosidase (EC 3.2.1.23) activity also increased during ripening; however, unlike polygalacturonase, their level or activity was lower in inner than in outer mesocarp. Ascorbic acid could partially account for the increase in titratable acidity during ripening but contributed very little to the differences in titratable acid levels between outer and inner mesocarp. Heat treatment had no effect on either fruit softness or titratable acidity, but it markedly reduced the increase in ascorbic acid and polygalacturonase activity during ripening. Ripening, as reflected by changes in tissue softness and polygalacturonase activity, progressed outwardly from the interior towards the exterior of the fruit. The effect of heat treatment in suppressing polygalacturonase activity was relatively greater in inner than in outer mesocarp, suggesting that sensitivity of the enzyme to heat treatment may vary with stage of ripeness of the tissue.     

Prevention of HCl-ethanol induced gastric mucosal injury in rats by Garcinia cambogia extract and its possible mechanism of action

Oral pretreatment of rats with G. cambogia fruit extract (1 g/kg body weight/day at interval of 7 and 15 days) protected gastric mucosa against HCl-ethanol induced damage by decreasing the volume and acidity of gastric juice. Increased lipid peroxidation, decreased activity of antioxidant enzymes, altered levels of protein and glycoproteins in the ulcerated mucosa, and gastric juice were maintained at near normal levels in G. cambogia pretreated rats. The results suggest the anti-ulcer activity of G. cambogia by virtue of its ability to decrease acidity and increase mucosal defense.     

Genomic structure,QTL mapping,and molecular markers of lipase genes responsible for palm oil acidity in the oil palm (<Emphasis Type="Italic">Elaeis guineensis</Emphasis> Jacq.)

The degradation of triglycerides in oil palm fruit due to an endogenous lipase in the pulp is the main reason for acidification of palm oil, which causes major economic losses and is currently mainly associated with the FLL1 gene. We designed this study to identify all the major genes controlling differences in acidity and lipase activity in the oil palm fruit mesocarp and determine a molecular markers kit to allow marker-assisted selection of commercial varieties with low acidity. Not only one gene (FLL1) but three closely linked genes including FLL1 were found and characterized in LM2T_EgCIR184O12c, a bacterial artificial chromosome sequence of 231 kb. Intra-gene PCR-based markers were designed for these genes. A QTL gene co-localization analysis for oil acidity (percentage of fatty acids released) was performed on two mapping populations. It evidenced a single major QTL at our lipase gene loci, explaining 84 to 92% of phenotypic variation, and validating the main genetic control of palm oil acidification by FLL1 and/or by the two new lipase genes. The three lipase genes had high homology to demonstrated triacylglycerol lipases. While FLL1 shows the highest expression levels, the two other genes may also contribute to oil acidity. Our molecular markers of lipase genes and the associated major QTL is an important step towards marker-assisted selection of commercial varieties with low acidity.