The Utilization of Translocation Lines and Microsatellite Markers for the Identification of Unknown Cotton Monosomic Lines

Simple sequence repeats (SSR) have been applied as useful markers for understanding cotton genetics. In the last decade, chromosome-deficient stocks of Gossypium hirsutum L. were used in the development of chromosome substitution lines for G. barbadense L., G. tomentosum Nuttall et Seemann, and G. mustelinum Watt chromosomes or chromosome segments. Several DNA markers have already been assigned to the individual chromosomes of G. hirsutum. We created new cotton monosomic lines in Uzbekistan after irradiation of seeds by thermal neutrons or pollen gamma‐irradiation to complement other global efforts in the development of cotton chromosome substitution lines. The primary objective of this chapter is to report the use of chromosome-specific SSR markers and a well-defined tester set of cotton translocation lines from the Cotton Cytogenetic Collection at Texas A&M AgriLife Research to confirm chromosome specificity of monosomic lines in Uzbekistan cytogenetic collection of cotton. Our results have assigned several different monosomic lines to the chromosomes 2, 4, 6, and telosome 11 At‐subgenome and chromosomes 18 and 20 or 22 Dt‐subgenome. These lines will be very useful in molecular mapping, the creation of substitution lines, and cotton breeding

IDENTIFICATION OF CHROMOSOME DEFICIENCY IN MONOSOM HYBRIDS USING DNA MARKERS TECHNOLOGY

There are many monosomic lines in a unique cytogenetic collection of cotton (G.hirsutum L) in Uzbekistan. It is not possible to determine the number of missing or defective chromosomes in monosomic lines. Obtained results from elucidating of monosomic hybrids of cotton using DNA marker technology were described in this article

Features of Chromosome Introgression from Gossypium barbadense L. into G. hirsutum L. during the Development of Alien Substitution Lines

The creation of G. barbadense L./G. hirsutum L. chromosome-substitution lines is an important method to transfer agronomically valuable traits from G. barbadense into G. hirsutum. In this study, 30 monosomic lines of G. hirsutum from the Cytogenetic Collection of Uzbekistan, created in the genotypic background of line L-458, were used in crosses with the G. barbadense line Pima 3-79 to create substitution lines. In the course of this work, new monosomic lines were identified for chromosome 12 and monotelodisome 6 of the Atsubgenome and for chromosomes 17, 21, and 22 of the Dtsubgenome using chromosome-specific SSR markers and a well-defined tester set of cotton translocation lines (USA). Compared to those in the F1 hybrids, a strong decrease in the crossing and setting rates was found in the BC1F1 backcross lines, with the substitution of chromosomes 2, 4, 6, 7, and 12 of the Atsubgenome and 17, 18, 21, and 22 of the Dtsubgenome. The F1 and BC1F1 offspring from interspecific crosses differed in their transmission of univalents. Despite the regular pairing of chromosomes and the high meiotic index, interspecific aneuploid hybrids were characterized by a decrease in pollen fertility, which may indicate hidden structural variability in these genomes that did not affect meiotic division. The identification of chromosomes using chromosome-specific SSR markers in the early stages of plant development has greatly accelerated the detection of monosomic plants. The analysis of morphobiological traits revealed that monosomic F1 hybrids were more similar to the donor line, while BC1F1 hybrids were more similar to the recurrent parent but also showed previously undetected traits