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UDC 633.12:631.527
ELEMENTS OF GENETIC TESTING DIFFERENCES BETWEEN FAGOPYRUM ESCULENTUM AND F. HOMOTROPICUM AND SOME RESULTS OF INTERSPECIFIC HYBRIDIZATION IN SELECTION OF COMMON BUCKWHEAT
Fesenko А.N., Doctor of Biological Sciences Fesenko I.N., Candidate of Biological Sciences All-Russia Scientific Research Institute of Grain Legumes and Groats, Orel City, Russia E-mail: fesenko.a.n@rambler.ru, ivanfesenko@rambler.ru
ABSTRACT
It has been studied the inheritance of the differences between Fagopyrum esculentum and F. homotropicum for a number of features which important for breeding (weight of 1000 seeds, the number of nodes in a zone of ramification of the stem, seed dormancy). New approaches to accelerate the improvement of the interspecific hybrids were tested.
KEY WORDS
Buckwheat; Interspecific hybridization; Breeding; Genetics; Seed dormancy; Weight of 1000 seeds.
Interspecific hybridization with wild-type of autogamous Fagopyrum homotropicum considered as a promising tool selection of buckwheat, in the first and foremost, to increase resistance to inbred depression [1]. Besides, the wild species has several characteristics that could improve the efficiency of common buckwheat as cultivated form, for example, high homeostasis formation of the fruit, decreased remontant at inflorescence.
On the other hand, it is characterized by a number of wild species traits that are incompatible with modern representations of cultivated buckwheat (fine-particular, late ripening, dormancy of seeds, etc.). To improve efficiency of type F. homotropicum in the breeding program in 1996 and 2012. genetic studies of interspecies differences on several grounds were conducted, and also the methods accelerate adaptation of interspecific hybrids involving minimizing loss of genetic material in the form of being worked out wild populations were tested. The results of this work can be found in this article.
MATERIALS AND METHODS
Plant material. F. esculentum: sorts Molva (morphotype indeterminate), Demeter and Dikul (determinate morphotype) gomostilnaya line kk-2. F.homotropicum: sample (line) S9139 from the collections of the University of Kyoto. Interspecific hybrids in combination Molva x S9139, S9139 x Dikul, kk-2 x S9139.
Procedure. The investigations were carried out in the field. To characterize the architectonic vegetative hybrids efficient system the number of vegetarian nodes on the stem, the branches of the first order B1, B2, etc were determined. (Respectively, the first, second, etc. branches, count of branches from top to bottom). By no less than 100 plants of hybrid populations grown under in wide (10 x 30cm) seeding were analyzed. According to the analysis metameric formula of population (weighted average number of nodes on the stem and branches of the first order) was calculated: Stem + B1 + B2 + B3 ... B7. The study of yields was carried out according to the competitive crop variety testing: in northern soldier, an area of 10m2 plots, repeatability 4-fold. For genetic analysis of quantitative characters the algorithm of N.A. Sobolev was used [2].
Research was supported by the State contract 14.512.11.0063.
RESULTS AND DISCUSSION
Branching area of the stem and weight of 1000 seeds. Genetic analysis showed that the wild species are dominant negative alleles at loci controlling the variation in grain size (Table 1).
The number of vegetative nodes on the stem inherits additively (difference between the mean values of the trait in the hybrids of the first and second generations are not reliable). This indicates the possibility of the effective selection of morphotypes with optimal number of vegetative nodes on the stem and grain size in the early generations of interspecific hybrids, however, as the number of genes involved in the cleavage, usually large, for detection plants of desired phenotype a large sample study of plants requires.
Table 1 - Genetic control of quantitative differences between the number of attributes F. esculentum (P1) and wild-type F. homotropicum, line C9139 (P2) (1996)
Index Character
weight of 1000 seeds, gr the number of nodes in the area of stem branching, pieces
P1 (average) 21,5+0,34 5,0+0,08
P2 (average) 15,4+0,17 9,5+0,12
F1 (average) 20,1+0,16 7,6+0,14
F2 (average) 17,0+0,23 7,7+0,08
Measure of dominance -2,44 0,62
Epistasis measure 2,98 -0,51
Approximate number of genes 4 3
Period of Dormancy. The use of interspecific hybrids in breeding is complicated by the long period of dormancy, peculiar to type F. homotropicum and hybrids with its participation. It is believed that the period of rest may be due to either the influence of surface structures (seed coat, endosperm or perisperm) or characteristics of the embryo [3]. Research made by Wang YJ, Campbell CG [4] found that the period of dormancy of F. homotropicum concerned with the influence of the seed coat and endosperm, and the authors recommend the removal of these structures as a way to overcome dormancy. We have successfully used the standard method of improving germination of buckwheat seeds by heating for 3 weeks at 35-45°C. As a result of processing laboratory germination F. homotropicum and hybrids with his participation has increased significantly (Table 2).
Analysis of hybrids F2 (kk-2 x S9139) allows to suggest that an alternative to «the presence / absence of seed dormancy» in this combination is controlled by one locus (Table 3).
The validity of this assumption is confirmed by the fact that in obtaining lines based on hybrids F2 (F.esculentum x C9139 F. homotropicum) just one freshly harvested seed for replanting the selection of plants was enough, seeds of which had a period of rest, which is close to the seed F.esculentum.
Linkage of Genes of Determinate Type Shoots and of Limbic Fruit. Studies have shown that the D locus is linked to a gene controlling the limbic fruit: when crossed with the determinant form F.esculentum with F.homotropicum in F2 122 indeterminate type plants (114 of them — with limbic fruits and 8 - with usual) and 43 determinate type plants (4 of them - with limbic fruits and 39 - with usual) were received. From the above data it is clear that the signs of the "type of growth" and "a form of fruits" are inherited by single-gene. The frequency of recombination between them was 2.8%. Linkage of these features increases the proportion of determinants of nonlimbic fruit in worked population, and facilitates the selection of such plants.
Table 2 - Effect of heat treatment on the germination of freshly harvested seeds of interspecific
hybrids of buckwheat (1997)
Seed Germination,% (In brackets the number of analyzed seeds is indicated)
fresh seeds heated seeds
F.esculentum kk-2 87,0 (200) 94,5 (200)
F. homotropicum C 9139 3,5 (57) 56,3 (48)
F1 (kk-2 x C 9139) 5,5 (200) 86,0 (200)
F2 (kk-2 x C 9139) 22,6 (199) 92,5 (200)
Table 3 - Inheritance of the «period of dormancy» trait in the hybrid population F2 (F. esculentum line kk-2 x F. homotropicum C 9139) (1997)
Splitting Seeds share (%) 2 X 3 : 1 p** 3 : 1
not germinated germinated
observed 77,4 22,6
theoretically expected * 74,6 25,4 0,41 0,52
* Including the actual germination of parental forms and hybrids of F1. ** Probability of confirming a working hypothesis
Adapting of Indeterminate Interspecific Hybrids. The use of interspecific hybrids is complicated by "extensive" signs of F. homotropicum (late ripening, small-seeded etc.). At the same time, the dominance of such signs of wild species as a period of rest, late ripening and small-seeded increases the efficiency of selection in fissile generations morphotypes, more in line with modern notions of "cultural" buckwheat.
Interspecific hybrids retained the main shortcomings of F. homotropicum: late ripening, increased growth of branches, etc. In view of this, the time of ripening of zoning in the Orel region buckwheat varieties hybrids were unable to generate enough seed yield, despite the good ear grain content.
To adapt the interspecific hybrids with indeterminate type of growth we used reseeding hybrids with disabilities in the field of high seeding rate (3 million germinating seeds per hectare) and harvesting in the optimal for mid-season buckwheat varieties terms. Filter by habit wasn’t carried out in order to conserve the genetic diversity of hybrids. Morphological analysis of the plants of the initial population and in populations of passing to adapt to field conditions showed that in the three passages significantly increased the share of overripening (4-5 knots PDC) morphotypes in populations, which provided a significant reduction in the capacity of branching plants (Table 4). The data obtained confirms our early made conclusion that a major adaptive mechanism for improving of natural populations of buckwheat is the reduction of potential of the branch plants [5].
The yield of adapted population increased nearly five times, but its level did not exceed 30% of the varieties of the standard (Table 5).
Table 4 - Architectonics of vegetative sphere of interspecific hybrid plants (F. esculentum x f. homotropicum) indeterminate type (2008)
Population Average number of vegetative nodes, pieces. Metameric population formula
on the stem on the branches on the plant
initial 6,70 16,02 22,71 6,70+3,03+3,39+3,45+3,06+2,03+0,76+0,24+0,05
1 reseeding 5,93 14,92 20,85 5,93+2,67+3,07+3,47+2,67+1,80+0,93+0,29+0,03
2 reseeding 5,72 13,10 18,82 5,72+2,47+2,91+3,13+2,19+1,69+0,56+0,16
3 reseeding 5,48 12,04 17,42 5,48+2,42+2,80+3,12+2,20+1,20+0,20
Table 5 - Yield of interspecific hybrids of buckwheat (2008)
Variety Yield
t/ga % from the standard
Molva (reference) 2,58 -
FsiF.esculentum x F.homotropicum) - non-adapted population 0,35 13,6
F7 (F.esculentum x F.homotropicum), 3-time reseeding field 1,02 39,5
HCP05 0,353 -
Adaptation of Determinant Interspecific Hybrids. Interspecific hybrids of determinate types were much less suitable for breeding than indeterminate: determinate plants formed only 1-2 buds on the shoot [6] and differ by stunting (up to 30-40 cm), abundant branching and very low grain productivity.
For their improvement method of «evolutionary» selection was used. Seeds of hommostile plants of inter-species hybrids were sown in the field as a private method in a mixture of seeds of indeterminate varieties Molva. Stiff competition with taller indeterminate plants in condition of coenosis provided culling the least competitive genotypes, the presence of morphological markers (determinate type of growth) provided culling of intercrossed plants in the progeny. The next stage was to reseeding progenies and selection of long-columnar plants (giving only the offspring of noncrossing pollination) in order to overcome inbreeding depression and recombination of favorable alleles. This was followed by the next round of selection. Vector of selection in such an environment is aimed at improving the overall cardinality of plants, a large amount of the work through population (4-5 thousand plants) provides the screening of more productive genotypes, and the use of self-pollination - fixing the best genetic combinations of the progeny.
Holding three rounds of this selection allows not only reducing the potential for branching plants (Table 6) and the length of their growing season significantly, but also increasing the plant height and number of inflorescences on shoots up to grade level Dikul. Established as a result of this selection homostyle population did not differ significantly in terms of the yield of standard varieties Dikul (Table 7).
Table 6 - Vegetative sphere architectonics of interspecific hybrid plants (F. esculentum x f. homotropicum) of determinate type (2012)
Population Average number of vegetative nodes, pieces. Metameric population formula
on the stem on the branches on the plant
initial 7,14 22,07 29,21 7,14+2,38+2,82+3,29+3,58+3,51+3,11 + 1,93+0,87+0,40+0,18
elaborated 5,66 15,84 21,50 5,66+2,74+3,04+3,40+3,58+2,50+0,48+0,10
Table 7 - Yield of interspecific hybrids of buckwheat of determinate type (2012)
Variety Yield
t/ga % from the standard
Dikul (reference) 1,82 -
F11 (F.esculentum x F.homotropicum), 3-time 'evolutionary' selection 1,62 89,0
HCP05 0,251 -
Thus, although the species F.homotropicum can serve as a donor of features which are absent in cultivated buckwheat (low remontant, ability to adaptive management of the time of formation of the fetus, self-fertility), hybrids with a high proportion of germplasm of wild species in the genome (single crossing of F.esculentum x F . homotropicum) need serious exploring selection, first and foremost in the selection for earliness and accelerated rhythm of development. Effective method for breeding accelerating may serve the selection in a tough competition from more adapted plants of cultivated buckwheat.
REFERENCES
1. Fesenko, A.N. The use of interspecific hybridization in breeding buckwheat / A.N.Fesenko, N.N.Fesenko // Reports of the Academy of Agricultural Sciences. - 2002. -№ 5. - P.11-13.
2. 2. Sobolev, N.A. Hybridological analysis of polygenic traits / N.A. Sobolev // Cytology and genetic. -1976. Vol. 10. Number 5. P.424-436.
3. 3. Bewley, J.D. Seed germination and dormancy J.D. Bewley / / Plant Cell. - 1997. - V.9. -P.1055-1066.
