Collecting fruit genetic resources in the North Caucasus region^*

Sammlung von obstgenetischen Ressourcen im Nordkaukasus

Focusing on the genus Malus five gene centres are described by Zhukovsky (1965): The East-Asiatic centre (M. baccata (L.) Borkh.), the Middle-Asiatic centre (M. sie­versii (Ledeb.) Roem.), the Caucasian centre (M. orientalis Uglitzk.), the European centre (Malus sylvestris (L.) Mill. and its south Ukrainian, south Russian relative M. prae­cox (Pall.) Borkh.), and the North-American centre. According to Tzvelev (2001, cited in Schmidt, 2006) the distribution of the European wild apple also expands to the Northern Caucasus foreland. In the genesis of the domesticated apple M. × domestica Borkh., the predominant species is M. sieversii which has its centre of origin in Kazahs­tan. However, other species like the wild Caucasian apple M. orientalis, as well as crabapples from Europe (M. sylvestris), Siberia (M. baccata), Manchuria (M. mandshurica (Maxim) V. Komarov), and China (M. prunifo­lia (Willd.) Borkh.), probably also contributed genes (Hokan­son et al., 1997; Gharghani et al., 2009; Velasco et al., 2010).

M. orientalis (Fig. 1) is the main wild apple species in North Caucasus. It is notable for the dense pubescence of the hypanthium, pedicels and young shoots (Zhukovsky, 1965). According to Schmidt (2006) the species is highly polymorphic and occurs in community with Pyrus caucasica. It can be found in western sections of the east/west trade routes that eventually became the “Silk Road” in the Russian Caucasus as well as in Turkey. Comparative genetic studies using Iranian apple cultivars and landraces, wild Malus species and representative old apple cultivars revealed a high genetic identity between M. orientalis and M. sieversii, and a poor identity between M. orientalis and most other Malus species and cultivars. The close grouping of M. sieversii and M. orientalis is not surprising, probably due to close geographical distribution of these species around the Central Asian region (Gharghani et al., 2009).

Fig. 1. Naturally grown Malus orientalis. (A) Fruits on a tree grown at the roadside, (B) dropped fruits of a tree grown in the wood, (C) fruit diversity of naturally grown apple trees, (D) solitary mature M. orientalis tree grown in the open field.

The diversity of pear in the Caucasus region is tremendous and it may be accepted as the centre of origin of Pyrus; more than 20 Pyrus species can be found in this region (Zhukovsky, 1965; Schmidt, 2006). A range of species are involved in the genesis of domesticated pear. The most important wild relative is Pyrus caucasica Fed. (syn. P. communis L. subsp. caucasica (Fed.) Browicz) which is closely allied with the European wild pear species P. pyraster (L.) Burgsd. P. caucasica (Fig. 2) can be found in broad-leaved forest, on forest glade and edges, often along river valleys. The trees can reach heights of 25 m, characterized by bare shoots, round-ovate leaves and globular fruit (Schmidt, 2006). From the ancient time local people were dealing with selection and grafting. This region is a main centre for evolution of pear. It can be assumed that lots of spontaneous interspecific and intergeneric hybridizations took place. It is proposed that the technology of grafting was developed in particular in North Caucasus (Zhukovsky, 1965).

Fig. 2. Naturally grown Pyrus caucasica. (A + B) P. caucasica fruits, (C) naturally grown P. caucasica tree in the wood.

Besides wild apple and wild pear another fruit tree species which can be found abundantly in forests, forest edges or open areas of this region is Prunus cerasifera Ehrh., the myrobalan or cherry plum. The fruit size and coloration is highly diverse. Ellipsoid and round, yellow, red and blue fruits can be found (Fig. 3). This species obviously contributed to the genesis of the domesticated plum Prunus domestica L. Rybin (1936) reported on hybridization between P. cerasifera (2n = 16) and P. spinosa (2n = 32). In the Caucasus, these two species frequently grow side by side. In Majkop region Rybin detected highly sterile interspecific hybrids. Using artificial hybridization he resynthesized P. domestica. Zohary (1992) assumed that P. domestica evolved directly from the variable P. cerasifera.

Fig. 3. Naturally grown Prunus cerasifera. A Yellow fruits, B red fruits, C blue fruits, D collected stones, E naturally grown P. cerasifera tree with red colored leaves and fruits.

It has to be noticed that everywhere in the forest regions of the Caucasus beside wild relatives large areas are occupied by apple, pear and other fruit trees that have become wild. Old neglected orchards produced seedlings by natural seeding and exhibit an extraordinary genotypic diversity, thus affording a very valuable initial material for selection (Zhukovsky, 1965).

In recent years it was found that M. orientalis being an important species in the genetic background of the domesticated apple is a critical species that lacked representation in the Malus collection at JKI. As present cultivars of the commercial apple have a narrow genetic base and most commercial production is based on very few cultivars (Schwartau, 2011), Malus orientalis could be a valuable genetic resource for the domesticated apple potentially containing more genetic diversity for important horticultural and environmentally adapted traits. It does not have the diversity of fruit quality like M. sieversii, but may have contributed to the domesticated apple other valuable traits such as later blooming, adaptation to a wider array of habitats, and capacity for longer storage of the apples (Forsline et al., 2003). Volk et al. (2008, 2009) identified M. orientalis individuals that exhibited resistance to apple scab (Venturia inaequalis), fire blight (Erwinia amylovora), and cedar apple rust (Gymnosporangium juniperi-virginianae) from Turkey, Russia, Georgia, and Armenia. M. orientalis accessions were evaluated recently as resistant to Alternaria blotch caused by Alternaria alternata (Abe et al., 2010).

The expedition took place between August 22 and September 4, 2011. The main objectives of the expedition were: (1) Collect germplasm of Malus orientalis in its centre of diversity; (2) Collect other crop species found in association with apple; and (3) Expand contacts with Russian scientists to develop cooperation in maintaining ex situ collections and develop strategies for phenotypic and genotypic evaluation. During the expedition eight collection sites were visited which were designated in relation to the nearest village or town (Fig. 4). Most collections were made as seeds, and altogether 7,955 seeds were collected from 103 individual trees of Malus orientalis. Localities of collection are listed in Table 1. A global positioning system device was available for the collection permitting latitude and longitude to be associated with each site. The main area for collection was between 44°10’ N latitude and 40°26’ E longitude. The individual trees selected for seed collection were grown between 67 and 1,033 m elevation. The fruits were selected at random from trees at the collection sites. Depending from the crop load and the accessibility we collected between two and 20 fruits per tree, trying to get 10 samples. Fruit size of M. orientalis from the different sites was diverse (Fig. 1C), but not as much as stated in M. sieversii (Wiedow, 2006). A summary of total seeds collected is listed in Table 2. Besides seeds, from trees of local apple, pear, sweet cherry varieties scion bud wood was obtained for vegetative propagation of the original genotype. Strawberry plants of two species were also collected from the wild. The material obtained is listed in Table 3.

Fig. 4. Schematic illustration of collection sites of the expedition to Adygeâ and Krasnodar region.

Fig. 5. Apple and other fruit trees were mainly find on forest edges and river banks.

Fig. 6. Former Adyghe roads crossing rivers were also used to get deeper into the forest.

On August 25, we started for a one-day expedition from Timirâzeva to the stanica in the valley of the river Fars, south-east of Majkop. This place belonged also to the Circassian tribe of Abadzeks until their expulsion after the Caucasian war. Later there was founded the stanica Carskaâ which was renamed to Novosvobodnaâ in the Soviet era. On a hill plateau named Mamrûk-Ogoj (644 m) outside the stanica a historical monument (called Chapel) was erected in 1881 in honour of impe­rator Aleksandr II to remind his visit on September 17, 1861 at this place (Fig. 7A). Inside of the Monument was a bronze bust of the tsar. The monument was destroyed during the Civil war in the 1920s. On the plateau the tsar met a delegation of chiefs of the Caucasian tribes to negotiate the termination of the Caucasian war (Boromotov, o.J.(b)). The place was not selected by chance. From the hill side opens a beautiful panorama of Adygeâ: the little houses of the stanica in the valley of the river (Fig. 7B), small fields and large meadows, exploited in Soviet time by intensive grain production, the twin peaks of the mountain Fisiabgo and the back of the mountain Bogatyrka (Fig. 7C,D). The hill is surrounded by small forests where wild apple and pear trees can be found.

Fig. 7. Near stanica Novosvobodnaâ. A The historical monument at the hill plateau Mamrûk-Ogoj, B View to stanica in the river valley, C + D panorama around the monument.

On August 26, we discovered the region around the Experimental Station of VIR. The first place was at the hillside of river Šuntuk called Duln’naâ balka where we found very old trees of Pyrus caucasica in the beech forest (Fig. 8). There are also several ponds in the valley where wild apple trees can be found on the banks abundantly. A little higher in the hillside we stopped at large forest glades which were used in Soviet time for agricultural production. In this time they are not under cultivation, and the process of evolution can be followed by necked eye (Fig. 9). There are lots of seedlings of different fruit tree species in various ages on the glades. The seedlings, especially in apple, are very different in the phenotype (morphology and resistance to diseases). Side by side you can find seedlings extremely affected by apple scab and others completely healthy. There is a beautiful view from this place down to the wide Majkop valley and the river Belaâ (Fig. 10). Majkop means valley of apples in local Adyghe language.

Fig. 8. Old trees of Pyrus caucasica in the beech forest.

Fig. 9. The Caucasus region as a hot-spot for fruit tree evolution. A + B Large forest glades which were used in Soviet time for agricultural production, but now they are not under cultivation anymore. There are lots of fruit tree seedlings on these glades. C + D Apple seedlings susceptible and infected by various pathogens, E healthy apple seedling directly side by side to the infected once.

Fig. 10. Beautiful view from the hillside down to the Majkop valley and the river Belaâ.

On August 27, we started a round-trip tour from the Experimental Station of VIR in Timirâzeva, through Apšeronsk (Krasnodar region) to Hadyžensk (Krasnodar region). We found a lot of wild apple trees along the road between these two towns. From Hadyžensk we went along the valley of the river Pšiš through the village Šaumân up to the Šaumân Pass. We collected material along the road and in the nearest forests. Crossing the pass we turned to the East along the river Pšiš uphill through the village Gojth to the Armenian village Terziân where the road ended in the mountain forest. In this place we collected material from old Circassian pear.

The next day we returned from the side valley to the main road leading from Hadyžensk to Tuapse and went south to Black Sea coast crossing the Gojthskij pass. In the village Georgievskoe we turned to east the road into the mountains until we reached the aul Bolšoe Pseušho. In this aul we visited the gardens of Madin and of Ruslan Hagurov where we collected old apple and pear varieties. We found the well-known ancient pear cultivar Circassian Bergamot (Čerkesskij bergamot, in Adyghe – Hutemy) which was selected by local people from the wild (Fig. 11). It still survived in some regions. It is resistant to winter frost and pear scab. During ripening the fruit flesh is browning which is very much favored by local people. The fruits are used for jam and drying. We stayed overnight at village Šepsi on the river of the same name at the Black Sea coast. We collected plant material in forests and old orchards not far from the road.

Fig. 11. The old Circassian pear cultivar ´Bergamot Circassian’. Distinctly visible is the incompatibility of rootstock and scion at the grafting site which is characteristic for trees in Circassian gardens (found in the stanica Sevastopol’skaâ).

From Šepsi we started to return to Majkop. The first leg was from Šepsi through Tuapse when we visited the aul Aguj-Šapsug at the river Aguj north of Tuapse. This aul was the place of the largest community of the Šapsugs, a tribe of the Adyghe branch which is the original folk on the coast of the West Caucasus. In Aguj-Šapsug we visited the garden of Damir Nagučev and others. Here we found the well-known Circassian apple variety Čerkesskij Rozmarin (in Agyghe language – Aguemy). Later on we entered another tributary valley of the river Psebe where we visited the aul Psebe, also a Šapsug’s settlement of descendant families which decided not to emigrate to Turkey after the Caucasian war in 19^th century. The Šapsugs were engaged in agriculture, cattle and horse breeding, gardening, viticulture and bee-keeping. This area has been described for the so-called Circassian gardens. Visiting the above mentioned auls we met the local people and asked for very old Circassian varieties of apple and pear. In Psebe we visited the gardens of Šaban Alalo, V. Ačmizova and O. Alper.

We continued our way to Džubga and then turning northwards direction Gorâčij Klûč the next day, and then turned to east towards Hadyžensk. We collected plant material in the forest along the road, and returned to Timirâzeva.

On September 1, we made a short mission from Majkop south towards the plateau Lagonaki at the Caucasus ridge. We stopped and collected plant material in the surroundings of the village Kamennomostskij. In the forest such fruit species, like pear, apple, cherry, cherry plum, hazelnuts, walnut etc. can be found. In this area beside the wild species there are also single gigantic hundred years old pear trees. Beside top fruit species a lot of berry species can be seen: cornel cherry Cornus mas, hawthorn species Crateagus, arrow-wood Viburnum. The fruits are used by the local population for diet and medicine purposes. On this day we collected samples of Malus orientalis at different altitudes until 1,350 m when the vegetation changed completely from broad-leaved forest to conife­rous woodland. We ascended the mountains up to the Azišskij pass at 1,745 m. Exactly 69 years ago at this place an awful battle has been taken place between the Soviet and the German armies in World War II. The Soviet army succeeded to defend the pass from breakthrough of the German fascist army to the Black Sea. From the pass a beautiful view opens to the broad Alpine meadows between two karst mountain massifs. This area is well-known for the exciting waterfalls and caves. We took the route back to Majkop passing the Svâto-Mihaj­lovskij abbey near the village Pobeda. The abbey founded in 1878 was one of the most important men’s abbeys in the Caucasus region. In 1928 the Abbey was closed, the buildings were destroyed. Since 2001 the Abbey is being rebuilt. Close to the monastery complex there is an old orchard which dates back to the foundation of the abbey. The old trees were planted in rows; the orchard was in good condition. Based on the phenotype of the fruits we collected bud wood for vegetative propagation of old Russian and possibly foreign apple and pear cultivars (Fig. 12).

Fig. 12. The Svâto-Mihajlovskij abbey and the closely located orchard. A Main building of the Svâto-Mihajlovskij abbey, B old pear tree in the orchard of the abbey, C very old trees of traditional Russian and possibly foreign apple and pear cultivars, D Tree of the cultivar ´Antonovka polutorafuntovaâ’.

On September 2, we discovered the region around Timi­râzeva and tried to find another orchard of fruit trees, named orchard of Krylov, in the forests. We drove up to the so-called Kon’ Gora and descended by foot to the assumed place which really was found after a few kilometres. The trees remained in the forest as planted, however the situation of the orchard was awful and no fruits could be found, possibly due to extreme spring frost. The local guide told us that these trees are every year highly crop loaded. On the way back to the station we crossed again former agricultural fields where nature has completely taken over control. Lots of fruit seedlings are growing on meadows and former driveways. It can be assumed that these areas will be dense forests in a few years.

Practically in every region there were special kinds of fruit trees best suited for the region's climate. The Caucasian war in 19^th century and industrial development of agriculture in the 20^th century led to the decline of gardening and numerous old cultivars have been lost. A fundamental research on Circassian (Adyghe) gardens was provided by Nuh Ahmedovič Thagušev. He systematically studied tradition, history and experience of fruit culture which goes back centuries. He prepared maps showing the regions of cultivating apple, pear, plum, cherry, hazelnut, walnut, and chestnut and tried to reanimate the traditional Adyghe horticulture. Thagušev also described ancient cultivars as in apple as in pear (Mafehabl, o.J.) Remaining parts of ancient Circassian gardens can be find until now in places were Circassian people are still living. This is in Abchasia, Adygeâ, Karačaj-Čerkessiâ and other places of the North Caucasus.

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