Origin and Evolution of Pyrus

ORIGIN AND EVOLUTION OF PYRUS

Pears and their wild relatives have been cultivated for thousands of years in various regions, including Anatolia, Italy, France, and Belgium. British and French colonies were among the first to adopt pear cultivation, with Turkey being considered the homeland of Pears due to its abundance of diverse species and varieties. In Turkey alone, over 600 pear varieties are cultivated, boasting various characteristics in terms of morphology, ecology, and biochemistry.

Pears and apples are less resistant to cold and can only be cultivated up to 55 degrees latitude in the northern hemisphere, with pear cultivation possible in all regions of Turkey except the Mediterranean coastline. Specific varieties are indigenous to certain regions and are therefore essential for breeding.

Research suggests that Pears originated in the Caucasus region and spread to both Europe and Asia. Pear cultivation dates back over 4000 years, with different species of Pyrus available in most countries worldwide. In the Corvallis gene bank (Oregon, USA), 2031 Clonal Pyrus accessions, 327 seed lots of 36 taxa have been reported, including 844 European cultivars, 144 Asian cultivars, 87 hybrid cultivars, and 159 Pyrus species rootstocks.

European Pear cultivars were established in Greece over 2000 years ago and were well known by 300 B.C. Oriental Pears arose and were independently grown in China for more than 2000 years. Approximately 25.2 million tons of pears are harvested from 1.6 million hectares each year, second only to apples in the Maloideae family. Despite this, the genetic diversity in Pyrus species and their wild relatives and naturalized forms remains underexplored.

Pear export production is mainly from countries such as Argentina, China, Belgium, Netherlands, USA, South Africa, Chili, amongst others. In Pakistan, for example, the total area under cultivation is over 2115 ha.

Research has shown that the genetic diversity of Pyrus species is vast, with a large amount of variability within the cultivar Pyrus communis in the Spanish region. Studies have also revealed that Japanese Pear cultivars have evolved from Wild P. Pyrifolia, with western varieties evolving separately and independently from their eastern counterparts.

Pears have an intricate genetic composition that makes their generative cycle complicated. In general, pears demonstrate a disassociative inheritance that permits a polygenic inheritance assumption. Maximum agronomic structures also display a constant dissimilarity in ancestry, allowing a bi-genic disomic inheritance, with stable heterozygosity.

Overall, Pear cultivation is an essential part of economic activity in various countries around the world, with researchers continually exploring the phylogeny and genetic diversity of Pyrus species to improve and increase the variety and quality of the fruit.