Malus x domestica (apple tree)

Download this page in pdf format (can be old)

Back to top

Taxonomic lineage

cellular organisms - Eukaryota - Viridiplantae - Streptophyta - Streptophytina - Embryophyta - Tracheophyta - Euphyllophyta - Spermatophyta - Magnoliophyta - eudicotyledons - core eudicotyledons - rosids - eurosids I - Rosales - Rosaceae - Maloideae - Malus - Malus x domestica

Brief facts

• The apple is a small deciduous tree reaching 5-12 m tall, with a broad, often densely twiggy crown.
• The apple tree is one of the most widely cultivated tree fruits, and, probably, the earliest tree to be cultivated.
• Selection of apple fruits began millions years ago: over 7-10 million years, mammals, such as bears, acted as distribution vehicles by selecting the largest and juiciest fruits; a small, bird-distributed, cherry-like treat giving way to a large mammal-distributed form. Small apples have been shown to pass intact through a bear's gut. It should be noted, however, that apples seed retained in the apple core do not germinate.
• Molecular data indicate that the Central Asian wild apple could be most closely related to the domesticated apple. Archeological data suggest that in the late Neolithic or Early Bronze age, travellers on the great trade routes that ran from central China to the Danube, carried the seed of the Central Asian wild apple west, either in saddle bags or horses' guts.
• The important technique of grafting, where the variety can be preserved forever, was probably discovered in Mesopotamia at Mari, as early as 3,800 years ago.
• Many thousands of named domestic apple varieties (both dessert and cider) have been selected for hundreds of years in Europe, Asia and North America. Together with wild species, these are maintained in national collections as genetic resources for breeding, particularly as sources of resistance to apple scab (Venturia inaequalis), powdery mildew (Podosphaera leucotricha), and fireblight (Erwinia amylovora).

Photo credit: Jha G et al. J Biomed Biotechnol. 2009
Symptoms of Apple Scab disease.

Back to top

Developmental stages (life cycle)

Life Cycle Stages

• Seed stage MeSH Usually apple cultivars used as a rootstock are grown from seeds
• Seedling MeSH Usually seedling is used as a rootstock for grafting scion of desired cultivar on it after it is about 1 year old; also, most of new cultivars originate as seedlings, which either arise by chance or are bred by deliberately crossing cultivars with promising characteristics
• Sapling 2-4 years old tree wich consists of a rootstock and a graft of desirable cultivar
• Mature 5-10 years old tree; mature tree can bear 40-200 kg of apples per year
  • Flowering Apples must be cross-pollinated to develop fruit
    • Early flowering The center of the flower cluster, King Bloom, has opened
    • Full bloom 80% or more of the flowers on the tree or in the orchard are open
    • Petal fall Flower petals are falling from the tree
  • Ripening
    • Fruit set 8-15 mm fruits; during this period farmers thin the fruits; also, natural dropping of inferior fruits occurs
    • Green fruit 1-2.5 inches fruits (for Red Delicious cultivar); green or mostly green in color; by this time final fruit count has been determin.ged (no more fruit thinning and fruit dropping)
    • Ripe Harvestable fruit; final fruit size is a result of the number of fruit on the tree and the growing conditions that year

Apple fruit anatomy

Back to top

Appendix: apple fruit development

Janssen BJ, Thodey K, Schaffer RJ, Alba R, Balakrishnan L, Bishop R, Bowen JH, Crowhurst RN, Gleave AP, Ledger S, McArtney S, Pichler FB, Snowden KC, Ward S. Global gene expression analysis of apple fruit development from the floral bud to ripe fruit. BMC Plant Biol. 2008 Feb 17;8:16. PMID: 18279528

Apple fruit development. Apple fruit at various stages of development. A, 0 DAA, B, 14 DAA, C, 35 DAA, D, 60 DAA, E, 87 DAA, F, 132 DAA, G, 146 DAA. H, diagram of fruit development showing the timing of major physiological events and the sampling time points, adapted from [17–19]. Ripening is shown as a solid and dashed red, solid from the time of the climacteric and dashed for events prior to the climacteric. Bar = 1 cm.

Back to top

References

• Harris SA et al. Genetic clues to the origin of the apple. Trends Genet. 2002 Aug.
• Hood E. The apple bites back: claiming old orchards for residential development. Environ Health Perspect. 2006 Aug.
• Major topic "Malus": free full text articles in PubMed

Back to top