**1. Introduction**

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*Eriobotrya* is a genus of at least 22 species and 10 varieties or *forma* of evergreen fruit trees in the family of Rosaceae (Lin, 2007). *Eriobotrya* is native to east and southeast of Asia, of which only loquat (*Eriobotrya japonica* Lindl.) is cultivated for its valuable fruit. The hypothesized center of origin and center of diversity of loquat are located in the medium to lower Daduhe River and the southeast slope of Gongga Mountain in Southwestern China (Qiu and Zhang, 1996). Loquat was domesticated in China at least 2000 years ago and has been widely cultivated for fresh and processed fruit, as well as for its medicinal effect (Qiu and Zhang, 1996). Loquat was introduced into Japan, France, England, United States and various Mediterranean countries between 12th to 19th century. Today loquat is mainly distributed between latitudes 20 and 35° north or south from the equator, but it can be cultivated up to latitude 45° under marine climates (Lin et al., 1999). There are more than 30 loquat producing countries in the world and the production is distributed in Asia, Europe, Africa, Australia, and the America. In addition to the utilization of its fruit, loquat flower is a superior honey source and it mostly blooms in fall and early winter. The white flower is aromatic thus is appreciate as ornamental tree as well.

The global planting area was about 130,000 hectares, with the production over 549,220 tons in 2005. The main producing countries are China, Spain, India, Japan and Pakistan, which account for 97% of the planting area and 94% of the output respectively. In China, the planting area of loquat is more than 120,000 hectares with an output of more than 400,000 tons. The production in China is distributed in 20 provinces and the leading producers include Sichuan, Fujian, Chongqing, Zhejiang, Hunan, Guangdong and Guizhou. Many well-known loquat varieties originated from these provinces and are widely planted in China among which include 'Dawuxing', 'Longquan No.1', 'Zaozhong No.6'(Lin 2007a).

Genetic diversity and the relationships among different varieties of loquat are of great importance for the conservation of genetic resources, breeding, national and international exchange of germplasm (He et al., 2011). Research on genetic diversity of loquat based on pomological traits and molecular markers have been widely carried out (Badenes et al.,

<sup>\*</sup> G. L. Liang – Corresponding author

College of Horticulture and Landscape Architecture, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Southwest University, Chongqing,China

2000; Cai 2000; Vilanova et al. 2001; Soriano et al. 2005; Dong 2008; Qiao 2008; Watanabe et al. 2008; Gisbert et al. 2009; Yang 2009). These studies significantly enhanced our understanding about the distribution and structure of genetic diversity in loquat germplasm around the world.
