Development Of Homozygous Lines Research Articles

Development of Homozygous Lines by In Vivo Doubled Haploid Technique in Hybrid Maize Breeding

The maize breeding programs focuses on the development of homozygous parental lines for hybrid breeding to obtain heterosis. The Improvement of homozygous lines in a effective time is crucial for hybrid maize breeding. Objectives of this research were to obtain homozygous lines of maize in a short time by using of in-vivo maternal haploid (DH) technique and characterizing them morphologically. The experiments were carried out at the Eastern Mediterranean Agricultural Research Institute(EMARI). Inducers, RWS, RWK-76 and their hybrid RWS X RWK-76 were used as male parent. As female parent, 56 F2 segregated material obtained by selfing of 66 F1 hybrids developed in maize breeding program of Eastern Mediterranean Agricultural Research Institute (EMARI) and 2 F2 segregated material selected from the open pollinated plants of 9 commercial maize variety. As a result of the experiment, 29 doubled haploid lines (DH) were developed. In the developed DH lines, days to tasseling, plant height, height of first ear , ear length, ear diameter, number of kernel per ear and thousand kernel weight varied as 57-78 days, 151-248 cm, 43-112 cm, 11.20-24.50 cm, 24-45 mm, 224-537 kernels/ear, and 180-320 g, respectively. In conclusion, in-vivo maternal DH technique is a highly effective method for obtaining homozygous lines

Triticale haploidy <i>in vitro</i> (literature review)

Triticale (× Triticosecale Wittmack) is a hybridized grain crop developed from wheat and rye crossings. Today, triticale is a multipurpose commercial grain crop with great potential as a human food and animal feed. The sown area of the new grain crop in the world reached 4 million hectares in 2018, grain production was about 14 million tons. The current climate change, the rapid evolution of pathogens, as well as the requirements of the modern market dictate the necessity for accelerated development of varieties while reducing the cost of their development. The production of double haploids makes it possible to reduce the time required for the development of homozygous lines by an average of 5–7 years. For the mass production of haploid triticale plants in vitro, there are used two methods, namely anther/microspore culture and distant hybridization followed by selective chromosome elimination of the pollinator. The most critical factors for the success of developing haploids in anther culture are a genotype, growing conditions of donor plants, a microspore development stage, stress effects on heads or anthers, and a nutrient media. Among the unresolved problems of the method are a genotypic dependence, a high incidence of albinism and a presence of aneuploids in the androgenic plant progeny. The rye genome is more often involved in chromosomal transformations than the wheat genome. Most aneuploids are nullisomics, most often on the 2R and 5R chromosomes. Nullisomic plants for 2R and 5R chromosomes have fewer number of spikelets per head and fewer number of kernels per head. In order to develop haploids by the method of selective chromosome elimination during distant hybridization, there have been successfully used such grain crops whose pollen is insensitive to Kr-genes, as maize (Zea mays L.) and wild cereal grass ‘Imperata Cylindrical’ (Imperata cylindrical L.). The advantages of the method are less genotypic dependence, absence of albino plants, genetic stability of regenerants, and reduced costs for developing haploid plants. The length of flowering period of ‘Imperata Cylindrical’ and the absence of the need to combine the timing of flowering period of the parents ensure the economy and efficiency of using this species when developing haploid triticale plants. The purpose of the current review was to characterize the methods of mass development of haploid triticale plants, to describe their advantages and disadvantages when being used in the breeding process.