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Subject: search.filters.subject.Actinidia chinensis

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    Genomic architecture of resistance to latania scale (H. lataniae) in kiwifruit (A. chinensis var. chinensis)
    (BioMed Central Ltd, 2023-10-31) Flay C; Tahir J; Hilario E; Fraser L; Stannard K; Symonds V; Datson P
    BACKGROUND: Latania scale (Hemiberlesia lataniae Signoret) is an armoured scale insect known to cause damage to kiwifruit plants and fruit, which ultimately reduces crop values and creates post-harvest export and quarantine issues. Resistance to H. lataniae does exist in some commercial cultivars of kiwifruit. However, some of the commercial cultivars bred in New Zealand have not inherited alleles for resistance to H. lataniae carried by their parents. To elucidate the architecture of resistance in the parents and develop molecular markers to assist breeding, these experiments analysed the inheritance of resistance to H. lataniae from families related to commercial cultivars. RESULTS: The first experiment identified a 15.97 Mb genomic region of interest for resistance to H. lataniae in rtGBS data of 3.23 to 19.20 Mb on chromosome 10. A larger population was then QTL mapped, which confirmed the region of interest as the sole locus contributing to H. lataniae resistance. inDel markers mapping the region of low recombination under the QTL peak further narrowed the region associated with H. lataniae resistance to a 5.73 Mb region. CONCLUSIONS: The kiwifruit populations and genomic methods used in this study identify the same non-recombinant region of chromosome 10 which confers resistance of A. chinensis var. chinensis to H. lataniae. The markers developed to target the H. lataniae resistance loci will reduce the amount of costly and time-consuming phenotyping required for breeding H. lataniae scale resistance into new kiwifruit cultivars.
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    Non-destructive firmness assessment of ‘SunGold’ kiwifruit a three-year study
    (Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2024-02-14) Sneddon T; Rivera S; Li M; Heyes J; East A; Golding J
    Kiwifruit (Actinidia chinensis var. chinensis) firmness is routinely measured in a destructive manner for decision-making purposes. Thus, a population’s quality is inferred by measuring a sample from that population. Consequently, studies have investigated non-destructive techniques for measuring fruit firmness. However, most of these studies have been restricted to a single season or focused on performance over long-term storage. This work compared non-destructive compression (1 mm deformation) and acoustic stiffness with flesh firmness measured with a penetrometer across three seasons. ‘SunGold’ kiwifruit were harvested from 11, 9 and 3 orchards on multiple occasions in 2020, 2021 and 2022, respectively. Kiwifruit was freighted to Palmerston North and assessed on arrival. Thirty fruit per orchard were measured on lab arrival, whilst 24 fruit per orchard were stored for two weeks at 0°C prior to assessment. The non-destructive methods had a strong (r2 > 0.89–0.92) segmented correlation with flesh firmness (0.52–10 kgf). Flesh firmness could be adequately estimated with the non-destructive methods within a season. However, segmented regression performance was reduced when predicting for a season outside of the training population. Nonetheless, these non-destructive methods may be useful for estimating flesh firmness at harvest and after short-term storage (2 weeks at 0 °C).
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    Resource allocation in kiwifruit (Actinidia chinensis) : a thesis presented in partial fulfilment of the requirements for the degree Doctor of Philosophy in Plant Physiology at Massey University, Albany, New Zealand
    (Massey University, 2012) Boyd, Linda
    Kiwifruit growers in New Zealand receive financial incentives to produce high yields of fruit with high individual dry matter concentrations (DMCs). Several vine management techniques are available to growers to enable them to direct more resources into production of fruit rather than into other sinks such as root growth and shoot extension. The long term consequences of these management techniques are not well understood. The overall objective of the work described in this thesis was to investigate how manipulating whole vine source-sink relationships affects fruit quality, long-term vine health and productivity in ‘Hort16A’ kiwifruit vines. A compensatory reduction in flower numbers occurred as a result of whole vine carbohydrate depletion (famine treatment) and producing high crop loads of high DMC fruit with reduced leaf area (minimal pruning, standard nitrogen). Keeping crop loads low did not result in increased productivity, instead additional resources were allocated to root growth (feast treatment). Isolating the canopy from the roots by extended trunk girdling was the technique that enabled high flower numbers to be maintained across seasons. Increasing individual fruit DMC generally enabled fruit to be harvested earlier than fruit with lower DMC. This was because flesh colour change, the main harvest criterion, occurred earlier in fruit from treatments where DMC was increased. Fruit softening behaviour was less affected by changes in DMC than flesh colour change, meaning that low DMC fruit could be softer at commercial harvest that more mature high DM fruit. The implications of this finding for storage performance were discussed. Vines showed few of the common responses to carbohydrate depletion. There was no evidence of increased individual leaf area, reduced specific leaf weight, upregulated leaf photosynthesis or increased shoot growth. Uptake and allocation of some mineral nutrients within the vines was affected, but few visible signs of leaf nutrient deficiencies were seen. The results suggest that vines respond to carbon depletion primarily be altering resource allocation between flowering and root growth, rather than by altering its ability to capture carbon.
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    The sequences of the tryptic peptides from actinidin : a thesis presented in partial fulfillment for the degree of Doctor of Philosophy [in Biochemistry] at Massey University
    (Massey University, 1976) Carne, Alan
    Actinidin is a plant thiol protease which is isolated from the fruit of Actinidia chinensis, the chinese gooseberry. Determination of the primary amino acid sequence of actinidin was undertaken to extend the limited structural information available on this group of enzymes, and therefore enable a better understanding of their physical and chemical properties. The order of arrangement of the 220 amino acid residues in the primary sequence of actinidin was determined from the sequences of the tryptic peptides. S-carboxy[14C2]methyl actinidin was digested with trypsin, and the twelve tryptic peptides produced were initially separated into seven fractions by gel chromatography on Sephadex G-50. The first four fractions contained tryptic peptides that were purified by DEAE-cellulose chromatography. The last three fractions contained peptides that were sufficiently small to enable purification by paper techniques, and these peptides were sequenced directly by the dansyl-Edman method. Further degradation of the tryptic peptides purified on DEAE-cellulose with either chymotrypsin, thermolysin, pepsin or Staphylococcus aureus V8 protease was necessary to provide smaller peptides that could be sequenced by the dansyl-Edman method. S. aureus V8 protease was particularly useful in the determination of amide residues, because of the enzyme specificity for the carboxyl groups of glutamic acid. The fourth tryptic peptide in the sequence of actinidin could not be located in the tryptic peptide elution profiles of either the Sephadex G-50 or DEAE-cellulose columns. The sequence of this peptide was determined from a tryptic peptide obtained by digestion of maleylated carboxymethyl actinidin. The N-terminal of actinidin was determined by the dansyl Edman method, and the C-terminal by analysis of cyanogen bromide fragments, and by digestion with carboxypeptidase A. Radioactively labelling the active site cysteine residue with iodo[14C2]acetic acid, and subsequent purification of the radioactive tryptic digest peptide, enabled the isolation of the tryptic peptide containing the active site cysteine residue. Further digestion of this peptide with chymotrypsin and determination of the sequence of the smaller radioactive peptide provided the sequence about the active site cysteine residue. Alignment of the tryptic peptides to reconstruct the primary sequence of actinidin was accomplished with information from cyanogen bromide fragments, information from tryptic peptides of maleylated carboxymethyl actinidin, and information from the three dimensional X-ray crystallographic structure of actinidin determined by Dr E.N. Baker. The low proportion of basic residues and high proportion of acidic residues in actinidin are in agreement with the enzyme being an acidic protein. Colorimetric analysis of the tryptophan residue content, using 2-nitrophenylsulphenyl chloride, confirmed the presence of six tryptophan residues in the sequence of actinidin. The amino acid sequences about the seven cysteine residues and the single histidine residue in actinidin were very similar to the analogous sequences in papain and other plant thiol proteases. Furthermore, comparison of the primary sequence of actinidin with that of papain, and the fragments of sequence available for other plant thiol proteases, indicated a considerable homology throughout the sequences of these proteins.