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Aspects related to sunflower parasite orobanche cumana wallr with special reference to genetic resistance


Author: Gîscă Ion
Degree:doctor of agriculture
Speciality: 06.01.05 - Breeding and Seed Production
Year:2019
Scientific adviser: Maria Duca
doctor habilitat, professor, Moldova State University
Institution: Institute of Genetics, Physiology and Plant Protection of the ASM

Status

The thesis was presented on the 2 November, 2018
Approved by NCAA on the 25 January, 2019

Abstract

Adobe PDF document – 1.76 Mb / in romanian

Thesis

CZU 630.165.7+575.16+632.53]:633.854.78

Adobe PDF document 5.79 Mb / in romanian
128 pages

Keywords

sunflower, Orobanche cumana Wallr, diversity, resistance, genetic determinism, aggressivity, virulence, broomrape, physiological races

Summary

The thesis includes introduction, 4 chapters, conclusions and recommendations, bibliography consisting of 181 sources, 128 pages of text, 55 figures, 26 tables and an annex. The results of the research are reflected in 19 publications.

Field of study: plant breeding and seed production.

The purpose was to evaluate the virulence and impact of different populations of broomrape on the productivity indexes and the screening of sunflower germplasm to obtain resistant hybrids.

Objectives of the work: analysis of virulence and evolution of different populations of broomrape parasite; study of the genetic determinism of sunflower resistance to O. cumana.; evaluating of the initial ameliorative material and transferring of broomrape resistance genes using conventional amelioration methods; evaluation of the initial ameliorative material using molecular analysis methods (SCAR, RAPD markers); the evaluation of experimental and commercial sunflower hybrids to broomrape resistance; studying the influence of the broomrape attack on sunflower productivity indices.

Scientific novelty and originality. The paper presents a complex approach focused on the comprehensive analysis of the evolution of broomrape races and their virulence, in parallel with the germplasm evaluation related to parasite resistance, the study of genetic determinism of resistance and extensive comparative assessments of experimental hybrids in the field to reveal the impact of the broomrape on the qualitative and quantitative indices of productivity. For the first time, the genetic, molecular and physiological screening of sunflower genotypes used for breeding has been done and a series of perspective lines and hybrids resistant to broomrape under natural and artificial infection conditions were identified. Important scientific problem solved consists in the scientific validity of methodology for breeding to broomrape resistance using the complex of molecular, laboratory and field experiments, which allowed the revealing of the Or 5 gene in the most lines, the association of RAPD primers with resistance, tolerance and sensitivity to broomrape, identification of new sources of resistance and demonstration of the possibility for Or's genes transferring to perspective lines through backcross, which ensures the improvement of the breeding process and creation of competitive sunflower hybrids resistant to broomrape.

The theoretical significance. The study is a fundamental methodological basis of sunflower breeding for resistance to broomrape. Analysis of the genetic determinism of resistance to broomrape and identification of the mechanism of inheritance of dominant genes Or, demonstrates that resistance to the races of O. cumana more virulent than F is controlled by several genes and not just by a single dominant gene, as in the case of less virulent races (from A to F). These results of genetic determinism found up in two lines resistant to new races with increased virulence are of interest in the creation of resistant hybrids.

The applicative value of the work. Using the sources of resistance to O. cumana Wallr. the resistance genes were transferred to elite lines and lines with superior agronomical traits. They were created sunflower hybrids resistant to broomrape, 7 of them have been tested and admitted for production and marketing by the State Commission for Variety Testing. A method of early diagnosis of broomrape attack that allows rapid analysis of a large number of genotypes in a short time has been developed. RAPD markers tested in the paper may be recommended for primary screening of germplasm related to broomrape resistance.

Implementation of scientific results. The results of the scientific researches have been used in the elaboration of more than 25 sunflower hybrids, resistant to broomrape, which have shown a high productivity on the areas with increased infection in the Republic of Moldova and Romania. Seven of these are homologated and marketed on the domestic and international seed market. Annually, "AMG-Agroselect Comert" SRL produces 800.0 t of certified seeds and 30.0 t of basic seeds.