Maize chromatin introgression’s effect in oat × maize addition lines

The addition lines derived from oat (Avena sativa L.) × maize (Zea mays L.) crosses constitute a unique tool for studying gene expression and the structure of chromatin, as well as a source of agronomically desirable traits in the context of new intergeneric hybrid cultivars. Therefore, for a better understanding of the introgression of maize chromatin into the oat genome, a comprehensive analysis of oat × maize lines was conducted. The presence of maize chromatin was confirmed in three tested lines by PCR-based amplification of the maize retrotransposon Grande-1, and verified by genomic in situ hybridization. Interestingly, the addition lines containing cytologically-detectable maize chromosomes showed a possible disturbance of the Rabl-like centromere-telomere polarization typical for oat. Moreover, the maize chromatin was consistently positioned near the nuclear periphery. The maize chromatin introgression caused a prolonged DNA replication phase, altering cell cycle dynamics, and may led to mitotic abnormalities, such as the formation of micronuclei and anaphase chromosome bridges. The introgression lines also showed morphological and physiological changes: smaller seeds, hampered seedlings' growth, and reduced yield parameters (number of flowers/seeds per plant/panicle and seed weight). These findings shed more light on the consequences of the maize chromatin introgression into the oat genome and the stability and utility of the obtained hybrids.