The Exposure of Intra-specific Diversity of Linum usitatissimum as a Basis of the Development of Particular Flax Genetics and Breeding
Dr. Brutch N., Prof. Kutuzova S., Porochovinova E. ( )


The flax collection of N.I.Vavilov Research Institute of Plant Industry now consists of about 6 000 accessions. In this collection one can find the wide spectrum of intra-specific diversity for lots of morphological, biochemical, agronomic and other characters. It includes a large scale of differences in the duration of separate stages of vegetative period, plants height, fibre contents and quality, oil quality, colour of petals, anthers, seeds, resistance to diseases, etc. This is an inexhaustible source of any kind of initial material for creation of genetic collection and breeding.

About 20 years ago the creation of flax genetic collection was started in the department of industrial crops. At present it contains about 250 inbred lines carrying such traits as different duration of vegetative period, plants height, resistance to rust, colours of petals, anthers, seeds and plants, etc. Analyses of genetic control of this characters is carried out. In genetic collection there are lines carrying 5 rust resistance genes, allelic to those discovered by Flor and a new gene, which was found in our department. 11 genes, controlling colour and shape of flowers and seeds were identified. They determine white, violet and different hues of pink petal colours, yellow anthers pigmentation, yellow, light-brown and spotted seeds, star shape of flowers. 3 of them are allelic to those, reported by Plonka, but 2 were newer described by other others (star shape of violet flowers and sported seeds). In addition to that we always try to fined possible linkage between genes in order to start the creation of flax genetic maps. On the basis of genetic analyses donors of some agronomic characters were created for use in breeding programs.

The collection of flax and linseed in All Russia Institute of Plant Industry (VIR) is the oldest and one of the biggest collections in the world. It consists of about 6 000 accessions, originating from all continents. Also different kinds of material is included in the collection. In majority they are local folk breeded varieties, commercial varieties and some breeded accessions. Unfortunately, now in Russia and some other countries new commercial varieties are breeded using narrow circle of initial material. In addition to that, in Europe big areas are occupied by small amount of varieties. To prevent dramatic consequences of such situation, connected with possibility of epidemics and to breed new varieties well adopted to particular conditions of each region, a large scale of specific initial material is needed. Our collection was evaluated already for about 80 years [1-5]. During this time it was discovered that among accessions one can find sources for the majority of breeding characters. On the other hand, the development of flax genetics requires the use of wide scale of intra-specific diversity. To contribute to genetic research in flax, the creation of genetic collection was started in the beginning of 80s. Now this collection contains about 250 inbred lines, carrying different agronomic and morphological characters. For part of them genes, controlling their traits, are identified [6].

One of the most important agronomic character for both types of varieties is vegetative period. Especially earliness is needed for flax cultivated as spring crop. In high latitudes it gives an opportunity to obtain stable yields before cold period. In dry areas early varieties can reach maturity before the beginning of summer drought. First of all we must say, that oil type of plants has longer vegetative period, then fibre one. Unless flowering of linseed accessions often starts very fast, they are late in maturity. Among fibre type the majority of early accessions are old landraces, originating from the north of European part of Russia. From the best of them we have selected inbred lines (tabl.1).

Genetic analyses of each character requires maximum phenotypic diversity of it. Among fibre type we have some accessions, which ripen in 2-3 weeks later, then standard early variety Priziev 81: variety P-9 from Russia (k-6148), accession from Hungary (k-5969), varieties Medra (k-6577) and Mermilloid (k-6634) from former Czechoslovakia, Lin N 225 from Holland (k-5896).

The whole vegetative period consists of two main parts: period from germination to flowering and period from flowering to maturity. In our collection we have several accessions and lines with short phase from germination to flowering. Fast maturation after pollination is a very rear character. To accelerate the process of cultivation, breeder can diminish both periods. Evaluation of genetic control of needed character makes the breeding process easier. In order of this we have made genetic analyses of some lines with contrast duration of vegetative period phases [7,8]. We picked out the line 1, k-512, having maximum dominant genes, controlling period from germination to flowering, and the line 1, k-48, carrying dominant genes, controlling short period from flowering to maturity. On the basis of these lines later we created 2 donors of earliness, combining two short stages of the development.

It is known, that duration of vegetative period is positively correlated with the number of leaves [9]. The number of leaves was evaluated only for lines of genetic collection. The diversity of ripening time was confirmed by the diversity of leaves number. Minimum leaves number on the stem (less then 50) was found in early line 1, k-512 (Russia, Severo-Dvinsk). Late genotypes l-1, k-6917 (Versailles, France), l-1, k-6148 (P-9, Russia) and l-1, k-6634 (Mermilloid from former Czechoslovakia) had about 100 leaves. Maximum distance between leaves on the stem was also demonstrated by early tall lines: l-1, k-5522 (Russia, Palkinskiy Kriash), l-1, k-48 (Russia, Altgausen) and k-7880 (VIR-4, donor of rust resistance, created in VIR).

Another important character, especially for fibre flax, is the plants height. Some of early Russian landraces, mentioned above, have sufficiently toll plants (tabl.1). Maximum height of about 110 sm. was obtained in lines: l-1, k-6917 (Versailles, France), l-1, k-6148 (P-9, Russia), l-1, k-6815 (K-6, Russia), l-4, k-5512 (Russia, Leningradskaia region). Genetic control of this character was also evaluated in crosses between contrast lines [7,8]. L-1, k-48 was discovered to have maximum dominant genes, controlling plant's height. This line was recommended to be used in breeding programs for earliness and height improvement.

Fibre content in stem of flax plant is a very important breeding character. In VIR collection one can find the display of wide diversity of this trait (tabl.2). It shows the real possibility of breeding flax varieties with 40% of fibre in stems.

Unfortunately, lately breeders aspire to obtain varieties with maximum fibre contents. Usually it leads to the decrease of products quality. Our collection places to breeders and geneticists a disposal initial material with excellent characters of fibre quality. A wide scale of intra-specific diversity is also represented (tabl.3). The best in fibre quality commercial variety Orsanskiy 2 from Byelorussia is used as a standard. It has average number of long fibre - 20,3; line density - 2,25 teks; breaking load - 23,4 kgs; flaxibility - 68,8 mm.

For linseed varieties one of the most important characters is contents of oil. It should be mentioned, that flax has a great amount of oil in seeds and the scale of diversity for this trait is not so big. The difference of oil contents between fibre and oil types also is not essential (tabl. 4). The greatest success with this character was achieved in commercial linseed varieties, breeded in All Russia Institute of Oil Crops.

Flax oil is used for many purposes and it is important to have definite quality of the product. One of the main indications of oil quality is iodine number. The diversity of this character in flax is not very high (tabl. 5). For nutritional utilization contents of linolenic acid in oil is very important. Normally this substance forms the major part of oil. But this leads to fast oil oxidation. In Canada two famous low linolenic varieties, called Linola were breeded [10,11]. On the other hand, for medical purposes particularly linolenic acid is needed [12,13]. In VIR collection of flax high diversity of linolenic acid contents in oil was not found. Minimum amount of it presents k-8093 (R-7 from Canada) - 41,2%, the highest contents of linolenic acid has k-7924 (SV 65077, 80-41028 from Sweden) - 66,3%.

In breeding of each crop, resistance to the diseases occupies an important place. In VIR collection we have donors of the resistance to main flax diseases [14]. Flax rust now is the best evaluated disease. In our collection we have all differentiating varieties for rust resistance genes, identified by Flor. Genetics of rust immunity is studied in our department already for more then 25 years. Among old Russian landraces several accessions with resistance to rust were found. The genetic analyses of them and traditional differentiating varieties on infection background of Russian population of Melampsora lini discovered one new dominant resistance gene, named Q [15]. Later 10 donors of rust resistance were breeded (tabl. 6). Genetically they are lines - analogs of commercial varieties Orshanskiy 2 and Priziev 81. They were created by multiple backcrossing of lines, selected from resistant accessions by lines of varieties. In each generation phenotypes of father varieties with rust resistance were selected.

Besides, in VIR collection we have donors of rust resistance, created in All Russia Institute of Flax. Part of them shows some symptoms of the decease (tabl. 7).

In VIR collection we have donors of fusarial wilt resistance, created in All Russia Institute of Flax and Institute of Bust Crops of Ukraine (tabl. 8). Resistance to this disease could be controlled by one dominant gene, two duplicate genes or two complementary interacting genes [16]. Evaluation of donors of fusarial wilt resistance showed different degree of sensibility in different conditions. It could be due to different race compositions in populations of fungi.

In All Russia Institute of Flax donors of complex resistance to rust and fusarial wilt were created with the help of hybridization and further selection of resistant lines on infection background (tabl.9). Genes of rust resistance of donors G-5062 and G-4918 are identical. Additional gene of G-4918 gives an age resistance to the disease.

Cultivated flax does not have genotypes with high resistance to anthracnose, that's why varieties with maximum sensibility of 25-30% are considered to be good for growing. Inheritance of anthracnose resistance is polygenic. Development of the disease depends on the balance between dominant and recessive genes. Low degree of sensibility is determined by simple additive genetic system, without inter-allelic interactions [17]. In our collection we have donors, breeded in All Russia Institute of Flax (tabl. 10). They have 1-2 R-genes, which direction of dominance depends on the interaction of genotype and environment. During further evaluation of these donors it was discovered, that in several years they have worse resistance to the disease on the infection background. It shows the grate influence of the environment on phenotype. This situation makes difficult the creation of resistant varieties. But from the progeny of crosses between donors and susceptible lines and varieties, relatively resistant forms were selected. It confirms the possibility of their use in breeding.

Cultivated flax does not have forms with high resistance to pasmo disease. Several linseed accessions were found to have relative resistance (20-40%). Donors of this character were created in All Russia Institute of Flax by method of multiple selection from hybrid populations on the infection background (tabl. 11). Resistance to pasmo disease has polygenic inheritance and is sufficiently influenced by additive and non additive dominant genes, especially in k-7868 and k- 7889 [18].

The successful development of particular crop genetics requires maximum amount of morphological characters. They also could be used in breeding for marking commercial varieties, as it was made in Canada for Linola. In flax sufficient phenotypic diversity is presented only by shape and colours of flower organs and seeds. In our genetic collection we have lines with wide diversity of these characters. Several years ago the genetic analyses of them was started. Now 12 genes are identified. 9 of them expresses the same phenotype, as genes reported by Plonka [19]. For full identification of these genes, we selected lines from varieties, used by Plonka. For 3 of them test for allelism was carried out. One gene, fe was selected from variety Stormont Motley, evaluated in France. 2 genes, identified in our department have no analogs in bibliography. Here we display the list of identified genes.
rs1 - light brown seeds, acts only in seeds, manifest itself in genotype PF1- (phenotype is identical to rm gene, identified by Plonka)
pf1 - pink petals, orange anthers and light brown seeds (allelic to ad gene, identified by Plonka)
RPF1 - reduced pink colour of petals, manifest itself in genotype pf1, acts only in petals (phenotype is identical to Lr gene, identified by Plonka)
sfc1 - strengthens blue petals colour (PF1-) to violet and pink (pf1 pf1) - to dark pink, acts only in petals (phenotype is identical to nf gene, identified by Plonka)
s1 - white star shaped flower, orange anthers, yellow seeds, no anthocyanins in the plant; stops action of rs1; in genotype pf1pf1 petals have normal shape and seeds are light brown (allelic to pb1 gene, identified by Plonka)
wf1 - white colour of petals, filaments and stigma, codominant in petals and recessive in filaments and stigma; genotype WF1wf1s1s1 has semi star flowers; genotype wf1wf1pf1pf1 has white petals, orange anthers and light brown seeds; in genotype WF1wf1pf1pf1 petals are white, but become pink in HCl (allelic to nc gene, identified by Plonka)
ora1 - orange anthers and pollen, acts only in anthers, does not manifest itself in genotypes pf1pf1 and s1s1; in genotype WF1wf1 ora1ora1 petals are liter, then in WF1wf1ORA1- (phenotype is identical to ah gene, identified by Plonka)
sps1 - in genotype sps1sps1ora1ora1 manifest itself in spots on seeds (has no analogs in bibliography)
sbs1 - white star shaped flower, orange anthers, no anthocyanins in hypocotyl and flower (phenotype is identical to fan gene, identified by Plonka)
waf1 - white filaments, reduction of petal veins and stigma pigmentation (phenotype is identical to fb gene, identified by Plonka)
svf1 - star shape in violet flowers (has no analogs in bibliography)
fe - in the morning petals are pail blue, in one hour they become white (selected from Stormont Motley, in which Plonka had identified it).

In genetic collection we have lines with different combinations of genes (tabl. 12). During genetic analysis we continue to create new lines with new genes combinations. Also we try to find any linkage between characters. It was discovered that in l-3, k-6099 (Argentina) gene wf1(nc) is linked with early flowering. Except the described phenotypes, in collection we have lines with absolutely exotic appearance. Flowers can have star and semi-star shape of different colours, combined with different colours of seeds. Seeds can have various kinds of spots. The distribution of pigment in petals can also verify. Filaments can have bends. The whole plant and leaves can have pail green colour. The search for new phenotypes and their genetic evaluation is going on.

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By article: Brutch N.B., Kutuzova S.N., Porohovinova E.A.: The Exposure of Intra-specific Diversity of Linum usitatissimum as a Basis of the Development of Particular Flax Genetics and Breeding. - Proceedings of the second global workshop. Bust plants in the new millennium. 3-6 June 2001, Borovets, Bulgaria, p. 94-104    Top page

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