Morphology and microsatellites in Spanish apple collections
By A. M. RAMOS-CABRER, M. B. DÍAZ-HERNÁNDEZ and S. PEREIRA-LORENZO* Universidad de Santiago de Compostela (USC), Departamento de Producción Vexetal, Campus de Lugo, 27002 Lugo, Spain (e-mail: email@example.com) (Accepted 24 October 2006)
SUMMARY The populationof apple, Malus pumila Mill., indigenous to northwest Spain shows a wide range of ripening periods and fruit quality and is an unexploited resource for breeding programmes. The main purpose of this study was to fingerprint these accessions and to construct a molecular database including the cultivars commonly grown in Spain. A total of 77 indigenous and 26 international accessions were analysedusing ten microsatellite [simple sequence repeat (SSR)] markers. Some of the main morphological and agronomic characteristics, such as fruit weight, colour, shape, sweetness in ºBrix, flavour type according to content of malic and tannic acids, and harvest time were recorded. The 77 Spanish cultivars showed a unique fingerprint. We propose to preserve these 77 genetically different cultivars in ourGermplasm Bank, and recommend that 31 of them should be considered for a core collection to maintain all the diversity recorded. Some 29% of the cultivars showed three alleles at several loci and were confirmed, cytometrically, as triploids. These tended to produce larger fruit (15% by weight) than diploids. The use of ten polymorphic microsatellite markers provided a useful technique forfingerprinting apple cultivars in the Spanish germplasm resource and for indicating triploids. The fingerprints indicated that the famous triploid Dutch cultivar ‘Belle de Boskoop’ may be derived from an unreduced gamete of ‘Reinette de Caux’.
pple (Malus pumila Mill.) was cultivated in Egypt in the 12th century BC. Columella, a Roman writer on agriculture, born in Spain, wrote about graftingselected apple cultivars in the year 42 AD Greeks and Romans spread the crop across Europe. In the Middle Ages, apple culture was promoted around monasteries and, by the end of the 12th century, some famous cultivars such as ‘Pearmain’ and ‘Costard’ were already named (Morgan and Richards, 1993). Vavilov (1951) located the centre of origin for apple in Turkestan, Central Asia. The use of molecularmarkers has confirmed that the wild apple located in Central Asia (Malus sieversii) could be the major maternal contributor to the domesticated apple (Harris et al., 2002). Boré and Fleckinger (1997) and Luby (2003) pointed out that hybridisation with European crabapple, M. sylvestris, could have contributed to the diversity of local apple cultivars. The main use of apples is for the fresh market(O’Rourke, 2003), although processing is also important (Way and McLellan, 1989). Thus, in the USA, Germany and Australia, apples are processed into products such as juice, canned sauce, canned slices, dried apples, and frozen slices. Apples are also processed into vinegar, jelly, apple butter, mincemeat, and fresh slices, and small quantities are also made into apple wine, apple essence, baked wholeapples, apple rings, and apple nectar. Such products account for about 45% of apple production in the USA (Way and McLellan, 1989). Another important product is cider, made from fermented juice mainly in France, the UK and Spain and increasingly in the USA (Smock and Neubert, 1950).
*Author for correspondence.
In Asturias, in northern Spain, in an area where wine and beer are scarce, Straboreported that a beverage named “zytho” was common in 60 BC (Rivas, 2004). In the first century, “sicere” was described in manuscripts found in the Oubona monastery as being produced from apples collected from orchards named “pomaregas”. In the 10th century, cider was used to pay for goods (Rivas, 2004) and, in the 18th century, apple trees were planted profusely. In the 13th century, the press...