Improvement Of Quality Traits Research Articles

Identification and stability of QTLs for fruit quality traits in apple

Breeding for fruit quality traits is complex due to the polygenic (quantitative) nature of the genetic control of these traits. Therefore, to improve the speed and efficiency of genotype selection, attention in recent years has focused on the identification of quantitative trait loci (QTLs) and molecular markers associated with these QTLs. However, despite the huge potential of molecular markers in breeding programmes, their implementation in practice has been limited by the lack of information on the stability of QTLs across different environments and within different genetic backgrounds. Here, we present the results from a comprehensive analysis of the inheritance of fruit quality traits within a population derived from a cross between the apple cultivars ‘Telamon’ and ‘Braeburn’ over two successive seasons. A total of 74 different QTLs were identified for all the major fruit physiological traits including fruit height, diameter, weight and stiffness, flesh firmness, rate of flesh browning, acidity, the oBrix content and harvest date. Seventeen of these QTLs were ‘major’ QTLs, accounting for over 20% of the observed population variance of the trait. However, only one third (26) of the identified QTLs were stable over both harvest years, and of these year-stable QTLs only one was a major QTL. A direct comparison with published QTL results obtained using other populations (King et al., Theor Appl Genet 102:1227–1235, 2001; Liebhard et al., Plant Mol Biol 52:511–526, 2003) is difficult because the linkage maps do not share a sufficient number of common markers and due to differences in the trait evaluation protocols. Nonetheless, our results suggest that for the six fruit quality traits which were measured in all populations, nine out of a total of 45 QTLs were common or stable across all population × environments combinations. These results are discussed in the framework of the development and application of molecular markers for fruit quality trait improvement.

Applications of EcR gene switch technology in functional genomics

Genetic engineering of plants using transgenic technology is targeted to enhance agronomic performance or improved quality traits in a wide variety of plant species, and has become a fundamental tool for basic research in plant biotechnology. Constitutive promoters are presently the primary means used to express transgenes in plants. However, inducible gene regulation systems based on specific chemicals have many potential applications in agriculture and for enhancing the basic understanding of gene function. As a result, several gene switches have been developed. The ecdysone receptor gene switch is one of the best inducible gene regulation systems available, because the chemical, methoxyfenozide, required for its regulation is registered for field use. An EcR gene switch with a potential for use in large-scale field applications has been developed by adopting a two-hybrid format. In a two-hybrid switch format, the GAL4 DNA binding domain (GAL4 DBD) was fused to the ligand binding domain (LBD) of the Choristoneura fumiferana ecdysone receptor (CfEcR); and, the VP16 activation domain (VP16 AD) was fused to the LBD of Locust migratoria retinoid X receptor (LmRXR). The sensitivity of the CfEcR gene switch was improved from micromolar to nanomolar concentrations of ligand by using the CfEcR:LmRXR two-hybrid switch. In this report, we demonstrate the utility of CfEcR:LmRXR two-hybrid gene switch in functional genomics applications for regulating the expression of a Superman-like single zinc finger protein 11 (ZFP11) gene in both Arabidopsis and tobacco transgenic plants.

Agrobacterium tumefaciens-mediated transformation of Narcissus tazzeta var. chinensis

Phytoene synthase (PSY), as a key regulatory enzyme for carotene biosynthesis, plays an important role in regulating color formation in many species. In the present study, a protocol was developed for the transformation of Narcissus tazzeta var chinensis using Agrobacterium tumefaciens strain LBA4404 harboring a binary vector pCAMBIA1301 plasmid which contained an antisense phytoene synthase gene, a reporter beta-glucuronidase gene and a selectable marker hygromycin phosphotransferase gene. Effects of some factors on efficiency of transformation and regeneration were examined. Preculture of the explants for 6 days before inoculation enhanced the transient GUS expression. The addition of acetosyringone (AS) at 100 micromol l(-1) for inoculation and a period of 3 days co-cultivation yielded efficient transient GUS expression. Transformants were obtained through selection on MS medium containing 5 mg l(-1) 6-benzylaminopurine (BA), 0.1 mg l(-1)alpha-naphthalene acetic acid (NAA) and 40 mg l(-1) hygromycin. The transformation frequency was 1.24% based on PCR analysis of gus gene. One or two copies of transgene were demonstrated in different transformations by Southern blotting analyses. Northern blotting results confirmed that the transcription of the endogenous psy gene in transgenic plants was inhibited or silenced. The method reported here provides new opportunities for improvement of quality traits of Narcissus tazzeta via genetic transformation.

Feeding and management practices affect quality improvement in wild-caught edible crab ( Cancer pagurus)

About 80% of the Norwegian landings of edible crab ( Cancer pagurus) are females. Meat content is often poor also for hard-shelled crabs. Feeding has proved to increase the quality, however the feeding process is costly and should be as short as possible still providing the required product quality. The crab fishery season coincides with the females' reproduction period which affects the quality and body composition. Egg-carrying crabs are of no commercial value. The development of the gonads is therefore of great importance for a feeding management of crabs. A study was conducted to test if meat yield and quality increased over time in the peak season (September). Groups of females were fed a diet of saithe ( Pollachius virens) fillet for 10, 24 and 33 days. An unfed reference group was killed, boiled and quality assessed at the start of the experimental period and compared with fed groups assessed in the same way at the termination of the feeding period. The improvement of quality traits was a continuous process, with a linear increase in total subjective impression, hepatopancreas lightness and gonadosomatic index (GSI) correlated with time of feeding or cumulative feed intake. Two different methods of inactivating the claws, banding and nicking, were compared during the feeding period. The treatments gave no difference in feed intake or external quality like lost legs and tips. Gonad and hepatopancreas were examined during several short experimental periods (3–4 weeks) expanding from just before until after the peak fishery season. In August, September and October/November GSI increased but no increase was seen in hepatosomatic index (HSI). Crabs with GSI between 15 and 18 (%) seemed to be close to spawning. In October/November 40% of the crabs spawned, in December 6.7%. No development in GSI was present in December but HSI increased for fed crabs. After the peak spawning period in October/November most of the remaining crabs do not start the onset of gonad development before the following year. Fed crab at this time of the year will be of a different body composition, with more hepatopancreas and less roe. Several factors may influence the economy in a feeding program. However, the short feeding period makes it possible to feed several batches in a year. In a growing market and with increasing knowledge in quality grading technology of live crabs, feeding of edible crab may be worthwhile in the future.

Agronomic and qualitative traits of T. turgidum ssp. dicoccum genotypes cultivated in Italy

The increasing popularity of organic agriculture and health food products has led to a renewed interest in hulled wheat species such as emmer (Triticum turgidum ssp. dicoccumSchubler). Knowledge on agronomic and quality traits is required for effective and efficient use of germplasm collections in breeding programs. The objective of this study was to estimate agronomic and grain quality traits of emmer wheat cultivated in Italy. A total of 20 emmer accessions consisting of landraces, breeding lines or cultivars selected from landraces and modern cultivars were examined under low input conditions. The study was conducted for three successive years (2002–2004) at one location of Southern Italy (Foggia). The entries were characterized for agronomic and qualitative traits [grain yield (t ha−1), thousand grain weight (g), test weight (kg hl−1), grain protein content (%), HMWG composition, dry gluten content (%), gluten index and yellow index, alveograph indices and Total Organic Matter (TOM) on cooked pasta]. The results showed a large genetic variability for most of the traits measured and, even if most of the accessions showed inferior bread- and pasta-making performance, modern cultivars exhibited improved quality traits with some potential to perform healthy and tasty food.

Transgenic approach to improve quality traits of melon fruit

Melon is one of the economically important and widely cultivated vegetable crops in the world. There is a wide genetic diversity in the cultivated and wild species of melon. Melon as one of the most consumed fruits, the development and ripening of fruit is known to be a complex developmental process that involves many biochemical and physiological changes including the breakdown of chlorophyll, degradation of the cell wall, increase in sugars content, alteration in pigment biosynthesis, and the accumulation of flavour and aromatic compounds. However, the information on genetic engineering and molecular biology of melon is very limited. With the development of genetics and molecular biology, a large number of quality/ripening-regulated genes involved in pigmentation, vitamin, soluble carbohydrate metabolism, cell wall metabolism and ethylene biosynthesis have been identified in melons. Some genetic manipulations of melons have been proved to be useful technology to improve quality, sensory attributes, shelf life and other agronomic traits of melon fruit. This paper reviewed some progresses in the trangenic approach to improve quality traits of melon fruit.

Preliminary evaluation of diverse lucerne (Medicago sativa sspp.) germplasm to identify new material for livestock and cropping based farming systems in Australia

A preliminary evaluation protocol is described of Medicago sativa that enables a diverse range of germplasm from different winter-activity groups to be evaluated in the same experiment. The protocol was used to compare the seasonal growth patterns of very winter-dormant M. sativa sspp. falcata and caerulea accessions with highly winter-active M. sativa ssp. sativa accessions. Herbage production was strongly related to winter activity in the cumulative first year of growth and in second-year winter months, but completely unrelated in 3 cuts in the following spring. The vertical measurement of plant height was confirmed to be a good indicator of herbage production in winter, but neither stem height nor length were good indicators of spring production. The preliminary evaluation protocol identified highly winter-active class 10–11 germplasm with high winter production and excellent recovery after cutting, and accessions of M. sativa sspp. caerulea and falcata (winter activity class 1) with excellent spring and summer production. These wild relatives of lucerne have great potential to increase the area of cultivated M. sativa in Australia, largely as a component in pasture mixtures. They also offer improved quality traits over winter-active Lucerne, including a higher leaf to stem ratio, and a lower stem thickness and internode length.

The analysis of handsheets from wheat straw following solid substrate fermentation by Streptomyces cyaneus and soda cooking treatment

The recent interest in the utilisation of agricultural fibres has promoted research into their potential as raw materials for the pulp and paper industry. In the current study, we report on the effect of biological pretreatment of wheat straw by Streptomyces cyaneus on the performance of the handsheets produced from the treated pulps. The pre-treatment of wheat straw with S. cyaneus had a positive effect on both the burst and tear indexes of the pulps but had a negative impact on tensile index. No significant variation in permeability and in folding endurance was observed. Manipulation of handsheets from wheat straw through biological treatment may therefore result in improved quality traits.

BREEDING FOR FRUIT QUALITY

While fruit breeding programs have many different goals, including resistance to abiotic and biotic stress, tree architecture, precocity, and productivity, they all have in common the need to develop high quality fruit. Fruits come in a wide spectrum of size, flavor, color, firmness, and texture. Quality is defined differently for each fruit species and consists of many attributes. For some species, high quality flesh texture is crisp while in others it is soft and melting. Some fruit require a balance of acidity and sweetness while quality in others is simply defined by the degree of sweetness. This paper reviews the physiological and genetic basis for fruit quality traits and presents various approaches for improving fruit quality by breeding. INTRODUCTION Fruit breeding programs have a wide range of specific objectives such as increased cold hardiness or disease resistance. However, all commercial scion releases must have high quality fruit. It does not matter how disease resistant or productive the tree may be, if the fruit is not of acceptable quality it will not be a commercial success. Fruit quality is complex. There are many definitions and standards set by each industry but the simple definition of fruit quality is: Whatever the consumer desires (Barritt, 2001; Elia, 2001; Kupferman, 2002). Since people are different, their desires and ideas of quality are different and breeders need to provide alternatives to meet these market needs. How does the consumer perceive quality? The consumer initially judges quality by the appearance of the fruit at the point-of-sale and then by the taste of the fruit. The appearance will determine the first buy but taste will determine the return buy (Kader, 2002). The challenge for breeders is to provide an attractive fruit with desired taste that will survive the process of reaching the consumer. Attractiveness is usually based on fruit size and color, and taste is generally reflected on a combination of texture, flavor, aroma, and sugar to acid ratios. The process of getting the fruit to the consumer is dependent on the rate of softening and the overall control of the ripening process. This paper reviews the physiology of these traits and describes some new approaches for improving quality traits in fruit. FRUIT QUALITY TRAITS Appearance The characteristics that affect the appearance are primarily size and color. Consumer surveys in peach and apple have shown that bigger is better and consumers are willing to pay enough more to make larger fruit more profitable (Parker et al., 1991; Bruhn, 1995; Kupferman, 2002). Bright, clear colors are preferred (Francis, 1995). 1. Size. Fruit size has a large genetic component thus selecting for larger fruit is relatively straight-forward (Janick and Moore, 1996). Fruit size is a function of cell number, cell volume, and cell density (Coombe, 1976; Scorza et al., 1991). In tomato, introgressing wild type germplasm with small fruit size with commercial type germplasm with large fruit, a fruit size quantitative trait locus, fw2.2, responsible for 30% of the difference in fruit size was isolated. The gene was cloned and found to be associated with altered cell division in ovaries. Interestingly, the overall fruit yield in small and large-fruited plants was the same as the small-fruited isogenic lines produced more fruit than the large-fruited Proc. XXVI IHC – Genetics and Breeding of Tree Fruits and Nuts

Agro-biotechnology, innovation and employment

Several data sources are used to estimate the potential impact of innovation in agrobiotechnology on employment in the European agro-food chain. In the late 1990s, approximately 50,000 jobs were directly due to biotec hnology. The indirect employment effects are likely to be much larger. Four of the five main innovation strategies for new plant varieties are likely to reduce indirect employment, but the fifth, improved quality traits (such as enhanced oil content), could increase employment by cre ating higher value-added crops, although there will be job losses in industrial processing. Field test data for Europe and the United States show, however, that there has been no detectable shift in agro-biotechnology innovation towards quality traits. It could be worthwhile for government policy to increase funding for public research into these traits.

Heritability estimates of bread wheat quality traits in the Western Cape province of South Africa

The inheritance of wheat quality traits is complex due to the polygenic control of most of these characteristics. Furthermore, correlations and genotype × environmental interactions that exist among these characteristics, makes progress using conventional breeding procedures even more difficult. A diallel trial was carried out with parents and their F2progeny at Langgewens, South Africa, to determine the correlations, heritability and combining ability of the different quality characteristics. High narrow sense heritability was found for thousand kernel mass, flour extraction, breakflour yield, flour colour and hectolitre mass. Positive genetic correlations were observed between SDS sedimentation and falling number, mixograph development time and hectolitre mass, and loaf volume and flour protein content. Thus, genetic correlations, heritability and combining ability estimates can be used to design a selection strategy to improve quality traits.

Comparative viability and growth of hybrids between two sympatric species of sea urchins (Genus Echinometra) in Okinawa

Among the four sympatric but genetically divergent forms of the sea urchins belonging to Echinometra mathaei sensu lato, Echinometra sp. A (Ea) and Echinometra sp. C (Ec) were studied through a series of cross fertilization experiments and rearing of the resulting hybrids. Detailed investigations on their larval and adult growth, development and viability were carried out. Heterosis was judged at different stages from larval to 1-year-old F 1 hybrids of Ec(ova)×Ea(sperm) and Ea(ova)×Ec(sperm) and at the same time they were compared to their parental species controls. For simplicity the maternal species is named first in case of heterogametic crosses. The hybrids mostly appeared to be intermediate between that of the parental species. The average performance traits from fertilization to 3-month-old juvenile stages (viz. fertilization rate, larval survivality, metamorphosis rate, recovery rate of juveniles) of Ec(ova)×Ea(sperm) hybrids were significantly better than their reciprocal Ea×Ec hybrid but not significantly different from their conpecifics, Ea×Ea and Ec×Ec. After 1 year of rearing, the final mean weight attained by Ea×Ea, Ec×Ea, Ea×Ec and Ec×Ec was 14.7, 13.9, 13.6 and 9.2 g, respectively. Among the crosses, the growth of both the reciprocal hybrids were much faster than the conspecific Ec×Ec and slightly less than Ea×Ea. The weight increase by Ec×Ea and Ea×Ec hybrids were 51.7% and 48.4% higher over the conspecific Ec×Ec, respectively. The fast-growing Ea species thus partially transmitted this trait to the hybrids. Improvement of quality traits in the majority of the performance traits (viz. final weight, weight gain, gonad weight) in the F 1 hybrids compared to the parental species might have important implications to the development of a sea urchin fishery.

The Role of Plant Breeding in Improving the Nutritive Value of Forages

In recent years many public forage breeders have added breeding for higher forage quality to their programs. Genetic studies have revealed that improvement of quality traits may be slow because most quality traits have intermediate to low heritability. A reasonable selection scheme under these circumstances would be to progeny test large populations of parental clones over locations, harvests, and generations. This presents a problem related to the resources required to obtain quality measurements on large numbers of samples. Fortunately, a new technology, infrared reflectance spectroscopy, has been developed that has the capability of analyzing large numbers of samples for multiple quality factors. But even if this technology is available to the breeder, he must interface this quality information with other important plant criteria. To accomplish this the breeder needs a selection index to facilitate decision making regarding multiple traits. For this information the breeder can rely on animal computer simulation models to integrate both yield and quality data into a single selection index value. This total approach, considering both plant and animal factors in the breeding program, would make it possible for the forage breeder of the future to develop new forage varieties with greater profit in terms of animal production per unit of land area.