Pear genetic resources

Exploration and conservation of pear genetic resources
Iwateyamanashi (Pyrus ussuriensis Maxim. var. aromatica (Nakai & Kikuchi) Rehd.) is one of the Pyrus species grown wild in Japan.  The origin of the Japanese pear (P. pyrifolia) is uncertain but it has been suggested that Iwateyamanashi is the possible progenitor of the modern Japanese cultivar.  During the last few decades, the number of Iwateyamanashi trees has been decreasing and therefore, conservation is urgently needed.  After thirteen explorations in the northern Tohoku region of Japan, 615 pear trees and 22 local names were recognized mainly in Iwate Prefecture.  The center of the distribution seemed to be somewhere around Mt.Hayachine to the northern area of Kitakami highlands (from lat. 39‹ 20f to 40‹ 10f N, and from long. 141‹ 20f to 141‹ 50f E).  Four morphological characters concerning fruit shape, measured for 85 trees, showed a wide range of continuous variation.  For the skin colour of fruit 51% of trees bore russet type fruits, 22% smooth and 27% intermediate ones.  Most of the fruits had five loculi but Sanenashi fruits (seedless pear), one of the old cultivars, had three, and fruits of another two trees had four.  More than 80% of trees tended to produce fruits with a calyx but some trees bore fruits without a calyx.  These observations indicate a wide range of genetic diversity in Pyrus species which is caused, not only by high heterogeneity in Iwateyamanashi itself, but also by the coexistence of Iwateyamanashi, P. pyrifolia and hybrid progeny in this area.  Already 250 trees have been conserved as genetic resources by grafting at Food Resources Research and Education Center, KobeUniversity

Diversity of pear fruits collected from Iwate, Aomori, and Akita, Japan. Bigger three fruits in right side are Japanese modern cultivars (Uppre: Kousui, Middle: Housui, Lower: Nijisseiki)













@iNatural treasure pear tree, Kunohe-mura, Iwatej


Acknowledgements
Thanks are due to all of the people who allowed us to investigate their trees, who gave us important information about pear trees, especially Mr. T. Miura in Tono-shi and Mr. E. Nishiyama in Kunohe-mura.  This work was supported by a General Research Grant from the Nippon Life Insurance Foundation and Iwate Sanriku Foundation..




Typical fruits of Iwateyamanashi
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Reevaluation and utilization of wild pear genetic resources (Iwateyamanashi) as breeding materials

Many trees in Tohoku bore small fruits which were so hard, sour or astringent that they were not suitable to eat as fresh fruits.  People utilized such fruits after reducing the acidity and astringency by means of long term preservation in a eKamasugof (straw bag), boiling in the water or treating with brine.  Pear liquor prepared by soaking pear fruits in shochu liquor has been used as a cough medicine.  Exceptionally a few trees, including Sanenashi (seedless pear) produced juicy, sweet or scented fruits suitable to eat as fresh fruits.  

The timber of the pear tree is so hard that it is suitable for house construction e.g. as an entrance step or a frame of a hearth.  In Tono-shi, many pear trees were cut down in order to produce hair combs until the end of the Second World War.
One of the characteristics of Iwateyamanashi is an aroma, which is the origin of the Latin name of P. ussuriensis var. aromtatica.  Different aromas were recognized such as apple-like, European pear-like, or sweet aroma.  European pear fruits have a good fragrance, but the fruits of almost all modern Japanese cultivars have no aroma so that some trees found by this investigation can be used as breeding materials to introduce good aroma to Japanese cultivars.




(Other Research interests)

Origin of Japanese pear and iwateyamanashi using molecular markers (SSR, chloroplast DNA)
Chemical feature of fruits flavours in Iwateyamanashi
Molecular analysis of flavours related genes from pear


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600 pear trees collected from Tohoku region. (Food Resources Research and Education center, Kobe University)

There has been concern for a quite long time that plant genetic resources are endangered all over the world because of continuous land development and climate change.  Conservation of genetic diversity is important not only for wild species but also for cultivated plant species.  Monoculturalization has already driven out many local cultivars so the collection, conservation, evaluation, and propagation of local or old cultivars and wild relatives is urgently required before their extinction.  Fruit trees especially are strongly amenable for conservation by grafting or cutting, because generally they have genetically heterogeneous backgrounds.  Conservation of woody species requires a wide area of nursery and manpower. It is also time and money consuming work.  However, it is important to maintain genetic diversity by preserving germplasm collections for the future generations.