Similar but different: stability in genomic composition but differences in satellite DNA abundances between Brazilian and Chilean species of the genus Alstroemeria L. (Alstroemeriaceae)

OSCAR TORO; SADER, MARIELA A.; JÉSSICA NASCIMENTO; CARLOS BAEZA

Natal

Congreso; 67 Congreso Brasilero de Genética; 2022

Sociedad Brasilera de Genetica

Plant genomes vary greatly in size and sequence composition, particularly in their repetitive fraction. Repetitive sequences, like transposable elements and satellite DNAs, are the main components of plant genomes, playing an importantrole in the variation of genome size and structure and ultimately impacting species diversification and adaptation. The American genus Alstroemeria is distributed mainly in Brazil and Chile. The species of this genus are similar in relation to chromosome number (2n = 16) and karyotype asymmetry, all having very large genomes (above 18 pg). However, they show marked differences in terms of heterochromatin distribution, with several Chilean species having prominentheterochromatic bands, while Brazilian species have smaller ones. In the present work, we aimed to comparatively characterize the repetitive fraction of Brazilian and Chilean species to understand the influence of different repeat classes on heterochromatin organization in this group. For this, we used low-coverage sequencing of the Chilean species (A.exserens, A. hookeri, A. ligtu, A. philippi, A. pulchra, and A. violaceae) and of the Brazilian species (A. longistaminea, A. monticola and a new species, Alstroemeria sp.) for repeat characterization using the platform RepeatExplorer. Retrotransposons from the lineage Ty3-gypsy Tekay were the most abundant for all species analyzed, contributing to their large genome sizes. All repetitive elements were shared among species, except for some divergent Retand clusters present in Chilean species only. Alstroemeria philippi and A. violaceae were highly similar with respect to the general pattern of repeat abundances, suggesting a close phylogenetic relationship. Most of the highly abundant satellite DNA clusters were shared among all species, with a single cluster restricted to Chilean species, despite the age of the group (ca. 18 mya). Nevertheless, satDNAs showed a high variation in their genome proportions among species. Satellite DNAs were more abundant in four of the six Chilean species, such as Alstroemeria ligtu, with the highest proportion of heterochromatin. Thus, the proportion of different satellite DNAs in the genomes seems directly involved in the karyotype differentiation between Chilean and Brazilian species.