A. G. Seal

Plant and Food Research, Окленд, Auckland, New Zealand

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Publications (7)13.66 Total impact

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    ABSTRACT: BACKGROUND: Red colour in kiwifruit results from the presence of anthocyanin pigments. Their expression, however, is complex, and varies among genotypes, species, tissues and environments. An understanding of the biosynthesis, physiology and genetics of the anthocyanins involved, and the control of their expression in different tissues, is required. A complex, the MBW complex, consisting of R2R3-MYB and bHLH transcription factors together with a WD-repeat protein, activates anthocyanin 3-O-galactosyltransferase (F3GT1) to produce anthocyanins. We examined the expression and genetic control of anthocyanins in flowers of Actinidia hybrid families segregating for red and white petal colour. RESULTS: Four inter-related backcross families between Actinidia chinensis Planch. var. chinensis and Actinidia eriantha Benth. were identified that segregated 1:1 for red or white petal colour. Flower pigments consisted of five known anthocyanins (two delphinidin-based and three cyanidin-based) and three unknowns. Intensity and hue differed in red petals from pale pink to deep magenta, and while intensity of colour increased with total concentration of anthocyanin, no association was found between any particular anthocyanin data and hue. Real time qPCR demonstrated that an R2R3 MYB, MYB110a, was expressed at significant levels in red-petalled progeny, but not in individuals with white petals.A microsatellite marker was developed that identified alleles that segregated with red petal colour, but not with ovary, stamen filament, or fruit flesh colour in these families. The marker mapped to chromosome 10 in Actinidia.The white petal phenotype was complemented by syringing Agrobacterium tumefaciens carrying Actinidia 35S::MYB110a into the petal tissue. Red pigments developed in white petals both with, and without, co-transformation with Actinidia bHLH partners. MYB110a was shown to directly activate Actinidia F3GT1 in transient assays. CONCLUSIONS: The transcription factor, MYB110a, regulates anthocyanin production in petals in this hybrid population, but not in other flower tissues or mature fruit. The identification of delphinidin-based anthocyanins in these flowers provides candidates for colour enhancement in novel fruits.
    BMC Genomics 01/2013; 14(1):28. · 4.40 Impact Factor
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    ABSTRACT: Sex can sometimes lead to complications. In some crops, 2n gametes have been exploited by plant breeders to transfer genetic variation between taxa of different ploidy levels. However, their role and use in dioecious genera have received relatively little attention. In the dioecious genus Actinidia (kiwifruit), seedling populations usually segregate equally for females and males as sex is determined by an XX female/XY male system. While fertilization involving 2n egg cells is not expected to affect the sex ratios of progenies, fertilization involving 2n pollen is likely to produce progenies with excess males. The extent of sex ratio distortion will depend on the relative contributions of first and second division restitution, and the frequency and location of cross-overs in meiosis. In this study, seedlings recovered from crosses between females of hexaploid Actinidia deliciosa and males of two diploid species, Actinidia chinensis and Actinidia eriantha, included a proportion of pentaploid hybrids presumably derived from fertilization involving 2n pollen. Most of these pentaploids were male, and a proportion of them were likely to be carrying two Y chromosomes. If used as parents in further crosses, males with multiple Y chromosomes are likely to cause distorted sex ratios in their immediate progenies. In dioecious genera such as Actinidia, the effects on sex ratios of different mechanisms of ploidy change need to be taken into account when considering the evolution of polyploidy and the design of breeding strategies involving ploidy manipulation.
    Sexual Plant Reproduction 06/2012; 25(3):197-203. · 2.07 Impact Factor
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    ABSTRACT: While the roles of sugars and acids in fruit flavour are well known and described, the roles of volatile compounds that contribute to flavour and odour are more difficult to define. The determination of volatiles that make a significant contribution to the flavour of kiwifruit (Actinidia chinensis) is essential for efficient and cost effective flavour breeding. The aims of this study were to explore associations between volatile compounds, sensory and fruit attributes of A. chinensis fruit and to identify potential key flavour impact volatiles, superior parents and selection methods, using multivariate analysis. We investigated the volatiles produced by ripe fruit of 24 genotypes selected by principal component analysis (PCA) to represent the diversity of taste and fruit characteristics in a breeding population. Seventy-two volatiles were detected. Extended use of multivariate analysis proved powerful for gaining maximum information from the limited plant material. The volatiles were successfully grouped into four clusters, using hierarchical clustering of variables based on phenotypic correlations between volatiles to avoid a singular correlation matrix in PCA. Based on these clusters, associations between volatiles, sensory and fruit attributes were explored using PCA and multiple linear regressions. Principal components provided a measure of the balance of complex volatiles that is likely to affect consumer responses. Thirteen potential key impact volatiles that made a substantial contribution to the flavour of A. chinensis fruit were identified. Five esters were strongly associated with the flavours and odours characteristic of ‘Hort16A’. Volatiles associated with ‘sour taste’, ‘fruit ripeness’, ‘atypical ‘Hort16A’-like odour’ and ‘atypical kiwifruit flavour’ were also recognized. Parents with potentially desirable volatile profiles and a possible selection method for flavour breeding were identified. KeywordsKiwifruit–Breeding–Flavour–Volatiles–Multivariate analysis
    Euphytica 01/2011; 181(2):179-195. · 1.64 Impact Factor
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    ABSTRACT: We investigated the variability and inheritance of flowering in a seedling population of diploid Actinidia chinensis Planch. We found considerable variation in time to reach 50% flowering (D50) and flowering duration (FD). D50 was highly heritable (h 2 > 0.85) suggesting that this trait would respond well to selection in this population, whereas FD was greatly affected by the environment (h 2 < 0.20). The results also showed that the flowering times of male vines were more sensitive to the environment than those of female vines. However, significant specific combining ability (SCA) effects could be achieved by targeting specific bi-parental combinations for breeding and selection of flowering time. The diversity in flowering traits among males will facilitate the selection of male pollinizers that coincide in flowering time with present or future female cultivars. The possibility of breeding female cultivars with a short flowering period to improve the consistency of fruit maturity at harvest is discussed.
    Euphytica 01/2006; 147(3):395-402. · 1.64 Impact Factor
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    ABSTRACT: The current study illustrates that fruit breeding should not only target elite fruit that are significantly more liked than existing cultivars, but also target special unique fruit that create major new flavour niches. Breeding targets can be identified in terms of consumer preferences for new and defined flavours. A trained panel was used to assess the flavours of a wide range of kiwifruit, and these characteristics were systematically arranged into flavour and odour wheels. These wheels describe some of the diversity found within the kiwifruit germplasm. Next, consumers from Japan and New Zealand rated their overall liking of fruit from each of 10 genotypes. Consumer preference mapping was used to explore the relationships between consumer liking and flavour. Cluster analysis was used to explore the diverse responses consumers may have to the same fruit. Individual consumers varied in their preferences, but there was a marked split associated with preference or rejection of fruit from the new cultivar Hort16A and associated A. chinensis genotypes. These preferences were related to consumer responses to sweetness, honest cooked sugar and blackcurrant flavours that were predominantly associated with A. chinensis genotypes, and absent in previous commercial kiwifruit cultivars. The first significant export of Hort16A fruit occurred in 1998. Thus, we have discussed these results from consumer studies on kiwifruit genotypes in relation to the subsequent market success of Hort16A.
    Euphytica 12/2004; 141(1):93-104. · 1.64 Impact Factor
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    ABSTRACT: We investigated the variability and inheritance of taste components and fruit size and number in a seedling population of diploid Actinidia chinensisPlanch. We found significant variation in all characters measured. Narrow-sense heritability estimates were high for vitamin C content, titratable acidity (TA), soluble solids content (SSC), fruit weight and dry matter content (DM), but low for glucose content, quinic acid content, and fruit number per vine. The genetic correlations between sugars (except myo-inositol), acids (except quinic acid), TA, vitamin C content, SSC and DM tended to be positive and moderate to high. However, correlations between these characters and fruit weight tended to be negative and moderate to high. The standardised coefficients () of multiple regression showed that SSC was highly dependent on the levels of fructose content, sucrose content and TA. Estimates of relative selection efficiencies (E) suggested that selection using SSC could be an efficient and convenient alternative to direct selection for improvement of sugar levels in kiwifruit. However, selection strategies based on SSC need to take account of its moderate negative correlation with fruit weight. Male and female parents useful for improving acid and sugar composition and fruit size were identified. One family was outstanding, as it combined large fruit size with high levels of SSC and DM.
    Euphytica 06/2004; 138(2):185-195. · 1.64 Impact Factor
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    ABSTRACT: An open access copy of this article is available from the publishers website. Chromosome numbers are reported for the first time for seven taxa of Actinidia: A. arguta var. purpurea, 2n = 8x = c. 232; A. deliciosa var. chlorocarpa, 2n = 6x = 174; A. deliciosa var. coloris, 2n = 6x = 174; A. glaucophylla, 2n = 2x = 58; A. guilinensis, 2n = 2x = 58; A. indochinensis, 2n = 2x = 58 and A. setosa 2n = 2x = 58. Ploidy variation has also been observed in A. melanandra and confirmed in A. chinensis var. chinensis: 2n = 2x = 58 and 2n = 4x = 116. Chromosome numbers for another 11 Actinidia taxa were found to be in agreement with those previously reported. Chromosome numbers were the same for male and female plants of the same taxon. Detailed studies of chromosome morphology was not possible under the light micro scope because of the small size of Actinidia chromosomes.
    New Zealand Journal of Botany 06/1997; 35(2):181-186. · 0.62 Impact Factor