A reproductive calendar of apomictic and sexual genotypes of Eragrostis curvula (Schrad.) Ness

Abstract

Weeping lovegrass (Eragrostis curvula) is a perennial forage grass nativeto southern Africa naturalized in semiarid regions of Argentina thatreproduces mainly by apomixis, showing full, facultative and sexualgenotypes. The type of apomixis present in E. curvula is diplospory,where the megaspore mother cell (MMC) undergoes mitosis instead ofmeiosis and there is no fertilization of the egg cell, only the polar nucleusis fertilized to form the endosperm. To study the genetic basis of thedifferent components of apomixis in this grass, it is important to be ableto recognize and isolate pistils at different developmental stages in orderto identify differentially expressed genes. The aim of this work was todevelop a detailed and precise reproductive calendar for its use intranscriptomic analysis. The methyl salicylate clarification method wasused in order to avoid the long process of paraffin embedding protocol,and the male and female developmental stages in anthers and pistilswere confirmed through Differential Interference Contrast microscopy.Five different growth parameters from pistils and anthers from differentgenotypes were registered during the mega and micro-sporogenesis andgametogenesis over more than 500 flowers. Pistil length was found easyto measure and effective to identify different developmental stages. Thisparameter was more reliable than anther length to infer the correct femaledevelopmental stage, providing an effective method to collect pistils atthe desired stage.