BackgroundThe polyphenolic products of the phenylpropanoid pathway, including proanthocyanidins, anthocyanins and flavonols, possess antioxidant properties that may provide health benefits. To investigate the genetic architecture of control of their biosynthesis in apple fruit, various polyphenolic compounds were quantified in progeny from a 'Royal Gala' × 'Braeburn' apple population segregating for antioxidant content, using ultra high performance liquid chromatography of extracts derived from fruit cortex and skin.ResultsConstruction of genetic maps for 'Royal Gala' and 'Braeburn' enabled detection of 79 quantitative trait loci (QTL) for content of 17 fruit polyphenolic compounds. Seven QTL clusters were stable across two years of harvest and included QTLs for content of flavanols, flavonols, anthocyanins and hydroxycinnamic acids. Alignment of the parental genetic maps with the apple whole genome sequence in silico enabled screening for co-segregation with the QTLs of a range of candidate genes coding for enzymes in the polyphenolic biosynthetic pathway. This co-location was confirmed by genetic mapping of markers derived from the gene sequences. Leucoanthocyanidin reductase (LAR1) co-located with a QTL cluster for the fruit flavanols catechin, epicatechin, procyanidin dimer and five unknown procyanidin oligomers identified near the top of linkage group (LG) 16, while hydroxy cinnamate/quinate transferase (HCT/HQT) co-located with a QTL for chlorogenic acid concentration mapping near the bottom of LG 17.ConclusionWe conclude that LAR1 and HCT/HQT are likely to influence the concentration of these compounds in apple fruit and provide useful allele-specific markers for marker assisted selection of trees bearing fruit with healthy attributes.

The comparative abundance of orchard pest leafroller larvae was determined on eight host plants in the vicinity of pipfruit orchards. The greatest numbers occurred in Canterbury, followed by Nelson, Hawke's Bay, and Central Otago. In Hawke's Bay, leafroller larvae were Ctenopseustis H9800Q obliquana (41%), Planotortrix octo (15%), Epiphyas postvittana (16%), and Cnephasia jactatana (9%), and were most abundant on poplar, willow, and alder. In Nelson, leafrollers were E. postvittana (25%), Planotortrix excessana (23%), C. obliquana (23%), and C. herana (22%), found on willow, alder, clover, poplar, gorse, broom, dock, and plantain. In Canterbury, larvae were C. herana (51%), E. postvittana (34%), and P. octo (15%), mainly on broom, gorse, alder, poplar, dock, and clover. Leafrollers were very rare on host plants sampled in Central Otago, despite their pest status in horticulture. A total of 1460 larvae were reared to adults from the four regions, with 31% parasitism, of which two thirds were Dolichogenidea tasmanica (Braconidae). Parasitism varied significantly between leafroller larval host plants. Removal of leafroller host plants through mowing, pruning, careful shelter selection or other means could usefully reduce the leafroller pest density, and risk of incidence on crops.

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Otago apricots (Prunus armeniaca L.) are damaged by the endemic leafroliers, Planotortrix octo Dugdale and Ctenopseustis obliquana (Walker), and an Australian species, Epiphyas postvittana (Walker), all of which are quarantine pests on export fruit. Mating disruption, using sex pheromones, represents one promising option for pest management with reduced insecticidal inputs for apricots. Two pheromone blends were used: one, designed to disrupt the two endemic species, was (Z)-5-tetradecenyl acetate and (Z)-8-tetradecenyl acetate, (25:75) and the other, for E. postvittana, was (E)-1 1tetradecenyl acetate and (E)-9,(E)-11-tetradecenyl-1 acetate (95:5). No moths of three leafroller species were caught in pheromone traps at the centre of 0.1 ha plots of apricot trees treated with polyethylene tubing dispensers, at 1000/ha, whereas those outside the treated area (70 m distant) continued to catch. In commercial orchards, dispenser blends prevented trap catch and reduced damage in apricots on 1-3 H97062

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