Uncovering Interspecific Genetic Diversity and Detecting Gene Exchange by Sexual and Asexual Stages of Cochliobolus Sativus

Abstract

Throughout the kingdom of fungi's evolutionary history, genome sequence analysis has shown that species within taxa have common genetic information. Interspecies gene exchange played significant role in the fast adaptive development and creation of new species of pathogen. We emphasize the need to enhance our knowledge on the processes and implications of interspecific genetic diversity and detecting gene flow of Cochliobolus sativus. In this experiment, a BLAST search in NCBI GenBank showed that all isolates were 99% identical to Cochliobolus sativus in both sexual and asexual forms. Sequence references for asexual isolates are KU194490.1 and KJ909776.1 and for sexual isolates are KC311473.1 and EF452447.1. Polymorphic fragments were found in 88.3% of asexual isolates and 77.73% of sexual isolates, according to DNA fingerprint analyses. An identical parental genetic similarity (94%) was uncovered between CS 24 and CS22; CS1 and CS11, CS3 and CS11. This experiment revealed the level of genetic relatedness between the parents and the F2 generation of C. sativus. In the asexual stage the maximum genetic distance was 71% and the minimum distance was 5%. Asexual isolate CS-01 (SL 01) and sexual (F2 generation) isolate CS2 were used as a single emerging point (ancestor) in both phases. Due to inbreeding and selfing, evolutionary distances in parent isolates varied from 71-93% to 72-89%. Interspecific genetic diversity exists in both sexual and asexual phase of Cochliobolus sativus which contributed to the quick adaptive development of new species. These findings show that local gene exchange occurs among the C. sativus species throughout both phases of reproduction. This study demonstrated the existence of evolutionary processes among the Cochliobolus sativus via hybridization and gene exchange in both sexual and asexual phases.

Keywords: Cochliobolus, Interspecific genetic diversity, evolution, sexual stage, asexual stage