Research Articles (Horticulture)

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Browsing Research Articles (Horticulture) by Subject "Apples"

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    Classification of 'Granny Smith' apples with different levels of superficial scald severity based on targeted metabolites and discriminant analysis
    (German Botanical Society, 2016) Mditshwa, Asanda; Fawole, Olaniyi A.; Vries, Filicity; Van der Merwe, Kobus; Crouch, Elke; Opara, Umezuruike Linus
    To study the metabolic changes in ‘Granny Smith’ apples with different severities of superficial scald, fruit were stored in normal refrigerated air (0°C, 95% RH) for 12 weeks followed by 7 d shelf-life under room conditions (20°C, 65% RH). Fruit were graded to five groups based on scald severity and analysed for ethylene, α-farnesene and 6-methyl-5-hepten-2-one (MHO) levels. Reactive oxygen species (ROS) were measured by confocal laser-scanning microscopy on apple peel treated with fluorescent probe 2’,7’-dichlorodihydrofluorescein diacetate. Ethylene production rate, α-farnesene and MHO contents and ROS intensity increased with increasing scald severity but declined in severely scalded fruit. Malondialdehyde (MDA) concentration in fruit peel, a measure of membrane damage, increased linearly (R=0.891) with increase in scald severity. Discriminant analysis was used to classify fruit by scald severity on the basis of metabolites accumulated. The stepwise model indicated that three attributes (ROS, ethylene production and MDA) contributed significantly (R2≥0.5) to the separation of the five scald severity indexes, with ROS having the highest contribution (partial R² =0.961; p<0.0001), followed by ethylene (R2=0.718; p<0.0001) and MDA (R2=0.578; p<0.0001).
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    Molecular characterisation of apple accessions with respect to aminocyclopropane-1-carboxylic acid synthase gene (ACS1) polymorphism
    (Czech Academy of Agricultural Sciences, 2020-02-07) Mhelembe, Khethani; Kriel, Johan; Bester, Cecilia; Louw, Esme; Roodt-Wilding, Rouvay; Tobutt, Kenneth
    The ARC apple gene bank collection was genotyped for the fruit expressed gene ACS1, in which a short-interspersed element (SINE) in the promoter is known, when homozygous, to correlate with the delayed ethylene production. Primers were designed amplifying products less than 500 bp and 224 cultivars of domestic apple were analysed, 169 not previously genotyped. Of these, 82 were aa (homozygous for the high ethylene allele at 202 bp), 73 were ab and 14 bb (homozygous for the low ethylene allele, with the SINE, at 339 bp). The difference between the allele sizes, 137 bp, observed in the current study is consistent with the indel of 138 bp originally described, but differs considerably from the indel of 166 bp reported in literature. In addition, 21 accessions of other Malus species were analysed. Only one, M. ‘Golden Hornet’, had the b allele, which suggests it may have been introgressed from M. pumila.