REPRODUCTIVE BEHAVIOUR AND SEED ORIGIN IN Habranthus robustus Herb. ex Sweet. (AMARYLLIDACEAE)

ANA I. HONFI; DAVIÑA JULIO R.; GIANINI AQUINO AC

Foz de Iguazu

Congreso; XXII International Congress of Genetics; 2018

SBG

Habranthus robustus is a South American bulbous ornamental species that behaves as self-compatible, with hercogamy and entomophilous pollination. Details of megagametogenesis and embryo sac constitution are unavailable for this taxon. The objective of this work is to characterize the reproductive behaviour of two accessions of H. robustus from Misiones, Argentina. Cytogenetic techniques, cleared ovaries observation by differential interference contrast microscope and the relative DNA content estimation by flow cytometry in seeds were used. H. robustus is a diploid species with 2n=2x=12 chromosomes and regular formation of 6 bivalents at meiosis. Megagametogenesis is bipolar on the micropile-chalazal axis and develops by two rounds of asynchronous mitosis. Mature embryo sacs have one oosphere, 1-2 sinergids, two polar nuclei and 1-2 antipodals. Relative DNA content of 60 seeds showed an embryo:endosperm DNA relationship of 2C:3C in 100% of the seeds analyzed. The embryo 2C value originates from the fusion of the reduced (n) egg cell nucleus with a reduced (n) male nucleus. The 3C value of the endosperm is the result of the fusion of two reduced polar nuclei from the embryo sac (n+n) and a reduced male nucleus (n). These results reveal that H. robustus progeny originates by sexual reproduction.