Apomixis expression in Eragrostiscurvula under stress conditions

DIEGO ZAPPACOSTA; ANA OCHOGAVÍA; JOSÉ ROMERO; JUAN MANUEL RODRIGO; MAURO MEIER; PABLO POLCI; INGRID GARBUS; SILVINA PESSINO; VIVIANA ECHENIQUE

San Diego

Conferencia; Plant & Animal Genome XXII; 2014

The international Conference on the status of plant & animal Genome Research

Over the past few years our research group has been analyzing the molecular mechanisms involved in the reproductive control of weeping lovegrass (Eragrostiscurvula [Schrad.] Nees), an apomictic perennial grass.This work was aimed at analyzing apomixis expressivity in Eragrostiscurvula plants subjected to three stress conditions: 1) tissue culture followed by a colchicine-induced ploidy change; 2) tissue culture and 3) water deficit. In the first system, a colchicine-induced polyploid plant (C) changed the expressivity of apomixis in a four year period, being highly sexual shortly after polyploidizationand  highly apomictic four years later. During this interval, genetic and epigenetic changes were also observed. While genetic variation led to diversification with respect to an obligate apomictic control, epigenetic variation resulted in increased similarity. Polymorphic sequences were mainly similar to transposable elementsand/or protein-coding-like sequences. In the second system, explants originated from near obligate apomictic plants were subjected to tissue culture. The expressivity of apomixis of a regenerated plant was analyzed immediately after treatment and nine years later. In this period, the levels of sexuality shifted from 45 to 0%. In the third model, near-obligate apomictic plants subjected to water stress showed an increase in expression of sexuality from 2 to 20%. As a whole, our results suggested that stress can temporarily activate sexuality in apomictic genotypes. At least in one system, this change was correlated with genetic and epigenetic modifications involving retroelementsand/or protein-coding-like sequences.