The genus Actinidia contains more than 66 species and 118 taxa. The best-known species is A. deliciosa C.F. Liang et A.R. Ferguson, the commercially developed kiwifruit. The natural range of Actinidia is remarkably wide, extending from the tropics (latitude 0°0′) to cold temperate regions (500°N). However, the original distribution of most taxa of Actinidia is centered around the mountains and hills of south-central and southeast China, with the QinLing mountain as its northern boundary and the HengDuan mountain as its western boundary. Sixty-two species, 114 taxa have been found in China. Genetic variation ranging from morphological traits to DNA is discussed in here. 1) Morphological variation (mainly horticulturally important traits): fruit size varies from 2 to 100 g, fruit skin color ranges from brown to green to white to purple, fruit surface from setose to villose, and flesh color from green to purple. 2) Nutritional value and flavor: vitamin C content varies from 10 mg/100 g to 1000 mg/100 g fresh fruit, soluble solids ranges from 2% to 22%, and flavor includes variation form bitter and astringent to desirable sour-sweet. 3) Gender variation includes six phenotype/genotypes of female, inconstant female, male, fruiting male, neuter and hermaphrodite. 4) Ploidy variation is consist of 2x, 4x, 6x, 8x in both intra- and inter-taxa variation. 5) Isozyme genetic variation: high polymorphisms were detected in commercial cultivated species and 28 wild species. 6) Genetic diversity was evaluated by RAPD, SSR, PCR-RFLP of mtDNA and cpDNA, a high level of genetic diversity was found in both inter-taxa and intra-taxa. Conservation strategy for diverse genetic resources of Actinidia in China is also discussed.
Social and environmental factors in the diversity of tomato landraces from the South-Central region of Mexico
