Phenetic analysis of natural apricot populations in the Mountainous Dagestan for endocarp (stone) features

Background. Studying the intraspecies diversity of fruit crop wild relatives is one of the leading trends in botanical and genetic resource research associated with identification and utilization of the phenotypic potential of the population and species, the initial stage in plant breeding and introduction processes, and a prerequisite to solving a number of problems posed by the theory of microevolution, biosystematics and population biology. Currently, large tracts of wild apricot populations (Prunus armeniaca L. = Armeniaca vulgaris Lam.) have been preserved in Central Asia, China and Dagestan. The natural populations of apricot in the Mountainous Dagestan are spread along the valleys of the Avar Koysu, Andi Koysu, Kazikumukh Koysu and Kara Koysu rivers, at altitudes of 350–1500 m ASL, and (sporadically) over the southern slopes – up to 1900 m ASL. They prefer crushed limestone hillsides, where they form the so-called ‘apricot savannah’, rarely assembling into dense massifs. With this in mind, it seems theoretically and practically interesting to evaluate various forms in the diversity of natural apricot populations in the Mountainous Dagestan, with qualitative traits of their endocarp (stone) as a target.

Materials and methods. To analyze the diversity of endocarp (stone) forms in natural apricot populations under the conditions of the Mountainous Dagestan, three model cenopopulations (CPs) were selected: in Gunibsky District, along the Kara Koysu (Lower Keger Vlg., 900–1200 m ASL) and Bagdakuli rivers (Salta Vlg., 900–1100 m ASL), and in Levashinsky District, along the Kazikumukh Koysu river (Burtanimakhi Vlg., 1000–1200 m ASL). Stones were collected along the slopes by using transect itineraries. Morphological description of endocarps was made for 328 trees according to 11 qualitative features by standard techniques.

Results. A comparative analysis of natural apricot populations showed high variation in the size and shape of the endocarp. Five classes were identified for stone size; of these, the very small (37.8%) and small (37.5%) types had the highest percentage. There were seven types of the endocarp’s shape (rounded, ellipsoid, ovoid, oblong, prolate, teardrop-shaped, and semicordate). Ovoid or rounded shape was observed in an overwhelming majority of apricot trees: their share was 65.3% of the total diversity. Correlation analysis of the endocarp’s features revealed credible positive correlations between the traits (1) ‘keel height’ and ‘rib width’, and (2) ‘lateral rib type’ and ‘rib width’. Creditable negative correlations were found for the trait ‘keel pattern’ with ‘lateral rib type’ and ‘keel height’.

1. Anatov D. M., Osmanov R. M., Asadulaev Z. M., Gaziev M. A. (2015) Ecological and historical aspects of the diversity of apricot forms in the Mountainous Dagestan (Ekologicheskiye i istoricheskite aspekty raznoobraziya form abrikosa v Gornom Dagestane). Bulletin of Dagestan State University (Vestnik Dagestanskogo gosudarstvennogo universiteta), vol. 30, iss. 1, pp. 73–81 [in Russian]

2. Asadulaev Z. M., Anatov D. M., Gaziev M. A. (2014) Genetic resources of Prunus armeniaca L. natural populations in Mountainous Dagestan. Acta Hort. (ISHS), 1032, pp. 183–190.

3. Avdeev V. I. (2012) Apricots of Eurasia: evolution, gene pool, introduction, breeding (Abrikosy Yevrazii: evolyutsiya, genofond, introduktsiya, selektsiya). Orenburg: Publishing Center OGAU, 408 p. [in Russian]

4. Denisov V. P., Lomakin E. N., Korneychuk V. A. (1988) COMECON wide unified descriptor list for the genus Armeniaca Scop. (Shirokiy unifitsirovanny klassifikator SEV roda Armeniaca Scop.). USSR, Leningrad: VIR, 36 p. [in Russian]

5. Kostina K. F. (1936) Apricot. Bulletin of Applied Botany, Genetics and Plant Breeding, Supplement 83, 290 p. [in Russian]

6. Kostina K. F. (1947) Origin and evolution of cultivated apricot (Proiskhozhdeniye i evolyutsiya kulturnogo abrikosa). Proceedings of Nikita Botanical Garden (Trudy Nikitskogo botanicheskogo sada), vol. 24, iss. 1. pp. 25–39 [in Russian]

7. Kostina K. F. (1965) Phytogeographic study of apricot for the purposes of breeding use (Botaniko-geograficheskoye izycheniye abrikosa v tselyakh selektsionnogo ispolzovaniya: Report for a scientific degree of Dr. Agric. Sci. Moscow, 36 p. [in Russian]

8. Mehlenbacher S. A., Cociu V., Hough L. F. (1991) Apricots (Prunus). In: Moore J. N., Ballington J. R. (eds) Genetic Resources of Temperate Fruit and Nut Crops.Acta Hort., 290, pp. 63–109.

9. Pomology. Stone fruit crops. Vol. 3. (Pomologiya. Kostochkovye kultury. T. 3) (2008), Orel: VNIISPK, 592 p. [in Russian]

10. Rokitsky P. F. (1973) Biological statistics (Biologicheskaya statistika). Minsk: Vyssh. Shkola, 316 p. [in Russian]

11. Vavilov N. I. (1960) Wild relatives of fruit trees in the Asian part of the USSR and the Caucasus and the problem of the origin of fruit trees. In: Selected works in five volumes (Izbrannye trudy v pyati tomakh), vol. II; Moscow; Leningrad: USSR Acad. of Sci. Publ., p. 343–360 [in Russian]

12. Vekhov V. N., Gubanov I. A., Lebedeva G. F. (1978) Cultivated plants of the USSR. Moscow, 336 p. [in Russian]

13. Zhukovsky P. M. (1964) Cultivated plants and their relatives (Kulturnye rasteniya i ikh sorodichi). Leningrad: Kolos, 791 p. [in Russian]