Comparison of tissue culture-induced variation in triticale regenerants obtained by androgenesis and somatic embryogenesis

Abstract

Triticale is becoming an increasingly important livestock crop production. This is evidenced by increasing triticale-producing areas and by improved yields. In addition, meeting the increasing demand for cereals involves the introduction of high-yielding and stress-resistant varieties into breeding. In vitro culture techniques can accelerate the development of new varieties. Therefore, it seems extremely important to develop efficient plant regeneration methods through in vitro cultures and to understand the mechanisms involved in gaining regenerants. Obtaining regenerants of triticale through somatic embryogenesis and androgenesis may lead to tissue culture-induced variation. In the present study, we compared regenerants obtained in both regeneration systems (anther and immature zygotic embryo cultures), considering the level of genetic and epigenetic changes observed in different DNA sequence contexts for methylated cytosine (CG, CHG, CHH). The changes concerning the DNA sequence (so-called sequence variation) and the changes concerning the DNA methylation patterns, i.e., the removal of methylated cytosine (DNA demethylation) and the introduction of methylation to cytosine (de novo DNA methylation), were analyzed. We observed that regenerants derived via somatic embryogenesis and androgenesis differ notably for demethylation in the symmetrical CG sequence context and de novo methylation in the asymmetrical CHH context. These changes may be related to the reprogramming of microspore development from gametophytic to sporophytic and lack of such process in zygotic embryos.