Identification of genetically plastic forms among Belarusian ancient flax (Linum usitatissimum convar. elongatum Vav. et Ell.) varieties using the Linum Insertion Sequence LIS-1

The Linum Insertion Sequence 1 (LIS-1) occurs in the genetically plastic flax genotypes in response to the lack or excess of mineral and water nutrition, but also naturally, and can be transmitted to the progeny. We have analyzed 21 ancient Belarusian varieties of flax Linum usitatissimum convar. elongatum Vav. et Ell. The LIS-1 presence or absence was checked for individual plants in at minimum two generations with primer-specific polymerase chain reaction (PCR) and agarose gel electrophoresis. The studied flax varieties formed four groups: non-responsive varieties (LIS-1 was not found, group NR); responsive, which formed and completely lost the insertion (group R0); responsive, which formed and retained LIS-1 (group R1); and responsive unstable (group R2). A statistically significant difference was found in ‘plant height’ (p < 0.05), ‘technical length of the stem’ (p < 0.05) between R0 and NR, and R2 and NR LIS-1 groups. The machine learning algorithm random forest classifier was used to predict the presence, absence or heterozygosity of LIS-1 in flax plants based on their growth and reproductive characteristics. As a result, the accuracy of the prediction was 98% on test data. In terms of sources for the selection of fibre flax varieties adaptive to environmental challenges, the most promising group consists of responsive varieties that have formed LIS-1 insertion (R0, R1 and R2 groups).