Submitted to: Journal of Heredity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/13/2006
Publication Date: 4/2/2007
Citation: Abdurakhmonov, I.Y., Kushanov, F., Djaniqulov, F., Buriev, Z., Pepper, A.E., Fayzieva, N., Mavlonov, G., Saha, S., Jenkins, J.N., Abdukarimov, A. 2007. The role of induced mutation in conversion of photoperiod dependence in cotton. Journal of Heredity. 98:258-266. Interpretive Summary: The genetic control of flower development in cotton has been the subject of considerable research interest. This is also important because a wealth of genetic variability exists in the primitive accessions of cotton, Gossypium hirsutum, and most primitive accessions require short days to initiate flowering and will not flower under termperate conditions. Many scientists are involved in developing day neutral types from the wild race accessions to utilize the wealth of genetic variability from wild race stocks using conventional backcross methods. DNA markers linked to day neutral traits can be helpful to expedite such breeding methods. The objectives of this work were to: 1)study the genome-wide effect of induced mutagenesis in photoperiod converted induced cotton mutants from their wild types; 2) study the genetic diversity between mutant and wild types using simple sequence repeats (SSR) markers; and 3) identify some potential SSR markers associated with day-neutral traits in cotton. SSR markers were used to study the differences between the wild types and their photoperiod converted induced mutant types in cotton. The 40 SSR markers revealed the same SSR mutation profile in at least two independent mutant lines that were different from original wild types. These results suggested that some of these SSR markers might be potential candidates as useful markers for day-neutral types. Genetic diversity based on SSR analysis showed the range from 0.09 to 0.60 in the cotton genotypes suggesting significant changes in some of the mutants compared to their originals. Outcomes of the research will help in understanding the photoperiod related induced mutations and finding potential markers useful for conversion programs from photoperiodic to day neutral types in cotton.
Technical Abstract: Wild cotton germplasms are largely underutilized because of photoperiodic flowering of exotic cottons. The objectives of this work were to explore the genome-wide effect of induced mutagenesis in photoperiod converted induced cotton mutants, estimating the genetic diversity between mutant and wild type cottons using simple sequence repeats (SSR) marker system as well as understand the pattern of SSR mutation in induced mutagenesis. Three groups of photoperiod converted radiomutants (32P) including their wild types and typical cotton genotypes were screened with 250 cotton SSR primer pairs. The 40 SSRs revealed the same SSR mutation profile in at least two independent mutant lines that were different from original wild types, demonstrating the same type of SSR mutations had occurred in these loci. Genetic distance obtained based on 141 informative SSR alleles ranged from 0.09 to 0.60 in all studied cotton genotypes. Genetic distance within all photoperiod converted induced mutants was in a 0.09-0.25 range, showing homogenizing effect of induced mutagenesis that created 75-91% similarity between these three independently mutated groups. The genetic distance among photoperiod converted mutants and their originals ranged from 0.28 to 0.50. This demonstrated that at least 28% change occurred in a genome around genotyped regions, revealing significant diversification of mutants from their originals. Typical G. hirsutum cultivars revealed close mutational patterns to induced radiomutants in 40 informative SSR loci, implying possible pressure to these SSR loci not only in radiomutagenesis, but also during common breeding processes. Outcomes of the research should be useful in understanding the photoperiod related induced mutations, and markers might have a potential in mapping of photoperiodic flowering genes in cotton using experimental populations in the future.