Changes in the genetic parameters of the plus gene pool of Scots pine in Mari El Republic influenced by a single clone selection by phenotype

The current study aims at assessing the risk of transforming the genetic structure and reducing the genetic diversity when the size of the selected population due to the selection of plus tree clones for phenotypic characteristics decrease. From 8 to 16 best clones were sorted out for different areas of selection having analyzed the phenotypic characteristics. The selection intensity was between 6.3–29.9%, while the selection differential was between 108.1–256.6%. Changes in the genetic parameters of selected populations were analyzed with the use of two types of DNA marker, namely nSSR and ISSR. We traced a substantive change in the frequency occurrence of ISSR markers in the groups of selected clones compared with the original sample. The allele frequencies of nSSR markers remained the same. The main threat of reducing the size of the selected population is the loss of allelic diversity in the case of nSSR markers (15.6–31.3%) and the number of PCR fragments in ISSR markers (11.8–19.9%). Other indicators of genetic diversity, such as effective allele number, heterozygosity, and inbreeding coefficient, have minor dependence on the size of the selected population. The number of effective alleles for nSSR markers varied in different groups of selected clones within 2.97–3.77 at an initial value of 3.47, the inbreeding coefficient was within 0.460–0.480 at an initial value of 0.503, and the expected heterozygosity was in the range of 0.325– 0.375 at an initial value of 0.355. We can observe a slight decrease in the number of effective alleles for ISSR markers, due to single selection from 1.31 to 1.28–1.29, and the expected heterozygosity from 0.205 to 0.175–0.193. To enable the monitoring of the genetic transformation of selected populations, we consider it feasible to carry out genetic certification of all selected plus trees. Furthermore, it is necessary to involve as many plus trees as possible in the breeding process while enabling the selection at the next stage of breeding without a crucial loss of genetic diversity.

1. Booy G., Hendriks R.J.J., Smulders M.J.M., Van Groenendael J.M., Vosman B. Genetic diversity and the survival of populations. Plant biology, 2000, no. 2, pp. 379–395. URL: https://doi.org/10.1055/s-2000-5958

2. Chudniy A.V. Selection of highly resin-producing pine trees and their use in the creation of plantations for tapping purposes. Thesis of dissertation, Sverdlovsk: ULTI, 1966, 18 p. (In Russ.)

3. Doyle J.J., Doyle J.L. A rapid DNA isolation procedure for small quanti-ties of fresh leaf tissue. Phytochemical Bulletin, 1987, nо. 19, pp. 11–15.

4. Dzialuk A., Burczyk J. Comparison of genetic diversity of Scots pine (Pi-nus sylvestris L.) from qualified seed – tree stand and clonal seed orchard. Ecological Questions, 2002, no. 2, pp. 89–94.

5. Ilinov А.А., Raevskiy B.V. A Comparative assessment of genetic diversity of natural populations and clonal seed orchard of Scots pine and Picea ×fennica in the Republic of Karelia. Ecological genetics, 2015, vol. 13, no. 4, pp. 55–67. (In Russ.)

6. Ilinov A.A., Raevsky B.V. Genetic diversity of scots pine trees of different selection categories in plus stands of Karelia. Ecological genetics, 2021, vol. 19, no. 1, pp. 23–35. URL: https://doi.org/10.17816/ecogen50176 (In Russ.)

7. Krivorotova T.N., Prochorova E.V., Sheikina O.V., Novikov P.S. Evaluation of clonal progeny of Scots pine plus trees on the collection-brood plot in the Republic of Mari El. Izvestia Orenburg State Agrarian University, 2013, no. 1(39), pp. 18–20. (In Russ.)

8. Krivorotova T.N., Sheikina O.V. Genetic structure of seed orchads and natural stands of Pinus sylvestris in the Middle Volga Region. Vestnik of Volga State University of Technology. Serija: Forest. Ecology. Nature Management, 2014, no. 1(21), pp. 77–86. (In Russ.)

9. El-Kassaby Y.A. Domestication and genetic diversity – should we be concerned? The Forestry Chronicle, 1992, vol. 68, no 6, pp. 687–700.

10. Muona O., Harju A. Effective population sizes genetic variability and mating system in natural stands and seed orchards of Pinus sylvestris. Silvae Genetica, 1989, vol. 38, no. 5–6, pp. 221–228.

11. Novikov P.S., Sheikina O.V. ISSR analysis of Pinus sylvestris trees appurtenant to different selection categories. Polythematic online scientific journal of Kuban State Agrarian University (Scientific Journal of KubSAU), 2012, no. 08(82). URL: http://ej.kubagro.ru/2012/08/ pdf/65.pdf (In Russ.)

12. Peakall R., Smouse P.E. GenAlEx6: Genetic analysis in Excel. Population genetic software for teaching and research. Molecular Ecology Notes, 2006. no. 6, pp. 288–295. URL: https://doi.org/10.1111/j.1471-8286.2005.01155.x

13. Raevsky B.V., Schurova M.L. The method for breeding and genetic assessment of Scotch pine clones at forest seed orchards. Siberian Journal of Forest Science, 2016, no. 5, pp. 91–98. URL: https://doi.org/10.15372/SJFS20160509 (In Russ.)

14. Raevsky B.V., Ignatenko R.V., Novichonok E.V., Prokopiuk V.M., Kuklina K.K. The Current State of Conifer Species Breeding and Seed Production. IVUZ. Forestry Journal, 2022, no. 6, pp. 9–37. URL: https://doi.org/10.37482/0536-1036-2022-6-9-37 (In Russ.)

15. Sheikina О.V., Gladkov Yu.F. Simulation of the indices of genetic diversity depending on the number of plus trees of Scots pine. Vestnik of Volga State University of Technology. Serija: Forest. Ecology. Nature Management, 2018, no. 1(37), pp. 33–44. URL: https://doi.org/10.15350/2306-2827.2018.1.33 (In Russ.)

16. Sheikina O.V., Lebedeva E.P. Experience of creating seed orchard plantation of higher genetic value in Chuvash Republic. IVUZ. Forestry Journal, 2010, no. 3, pp. 35–40. (In Russ.)

17. Shigapov Z.H. A Comparative genetic analysis of forest seed orchards (plantations) and natural populations of Scotch pine (Pinus sylvestris L.). Russian Journal of Forest Science, 1995, no. 3, pp. 19–24. (In Russ.)

18. Vidyakin A.I. Efficiency of plus breeding in woody plants. Conifers of the boreal area, 2010, vol. 27, no.1–2, pp. 18–24. (In Russ.)