Large vs small genomes in Passiflora: the influence of the mobilome vs the satellitome

SADER MA, VAIO M., ; CAUZ-SANTOS LA., DORNELAS MC.; MELO NF, VIEIRA ML.; PEDROSA-HARAND A.

Mendoza

Congreso; Congresso Latinoamericano de Genética; 2019

Sociedad Argentina de Genética

Passiflora L. shows different chromosome numbers (x = 6, 9, 12, with ancestral x = 6) and high variation in genome size (10-fold). The Passiflora subgenus (~26 Mya, Miocene) had a recent diversification correlated to genome size increase and chromosome change from n = 6 to 9 by ascending dysploidy. To understand how karyotypes evolved in this group, we generated whole-genome data (1× coverage) for Passiflora quadrangularis (2n=18; 1C=2.68 pg), P. cincinnata (2n=18; 1.42 pg), both from the Passiflora subgenus, and P. porophylla (2n=12; 0.21 pg, Decaloba subgenus). We analyzed the repetitive genome fraction using Repeat Explorer and localized the most abundant repeats by fluorescence in situ hybridization (FISH). P. quadrangularis (73% of repeats) and P. cincinnata (60%) showed high proportions of the LTR-retrotransposon Ty1-copia-Angela, with a dispersed chromosomal distribution. The second most abundant was the Ty3-Gypsy-Tekay, the most abundant in P. porophylla (28%), more proximally located. The few satellite DNA (satDNA) found in P. cincinnata and P. quadrangularis were subtelomeric or dispersed. SatDNA diversity and abundance was higher in P. porophylla, with 37 families of located in subtelomeric or pericentromeric positions. Species from the Passiflora subgenus showed a greater accumulation of repetitive DNA sequences, specially Angela, but smaller divergence and total abundance than P. porophylla in relation to satDNA. Thus, the mobilome, not the satellitome, is responsible for differences in genome sizes in the subgenus Passiflora.