The role of APOSTART in switching between sexuality and apopmixis in poa pratensis

Authors: ALBERTINI, EMIDIO - Universita Degli Studi Di Salerno; MARCONI, GIANPIERO - Universita Degli Studi Di Salerno; AIELLO, DOMENICO - Universita Degli Studi Di Salerno; Kindiger, Bryan; STORCHI, LORIANO - Dipartimento Di Agraria, Universita Degli Studi Di Sassari; MARRONE, ALESSANDRO - Dipartimento Di Agraria, Universita Degli Studi Di Sassari; REALE, LARA - Universita Degli Studi Di Salerno; TERZAROLI, NICCOLO - Universita Degli Studi Di Salerno

Submitted to: Genes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2020
Publication Date: 11/11/2020
Citation: Albertini, E., Marconi, G., Aiello, D., Kindiger, B.K., Storchi, L., Marrone, A., Reale, L., Terzaroli, N. 2020. The role of APOSTART in switching between sexuality and apopmixis in poa pratensis. Genes. 11(8):941-965. https://doi.org/10.3390/genes1108094.
DOI: https://doi.org/10.3390/genes1108094

Interpretive Summary: Apomixis, the asexual production of seeds without sex, is a major method of reproduction in numerous grass species. An understanding of the mechanism, control and transfer of the trait has the potential to transform plant breeding since it will allow newly generated cultivars to retain their traits from generation to generation. A molecular study of apomixs in the forage and turf species Kentucky bluegrass (Poa pratensis) were performed to identify the molecular mechanisms of apomixs. Previous efforts have identified a potential gene controlling apomixs in P. pratensis that was assigned the name, APOSTART. Studies performed on derivatives of various APOSTART gene expression products identified that it plays a major role in apomixs in bluegrass. This study indicates one derivative, identified as APOSTART-6, is expressed only in the flower tissue and exhibits delayed expression in apomictic genotypes when compared with sexual genotypes. Characterization of APOSTART-6 in a Texas bluegrass-Kentucky bluegrass population segregating for apomixe and sexuality, identified the APOSTART-6 sequence conclusively co-segregated with apomixs. This research identifies a gene controlling apomixs in Kentucky bluegrass. The identification of the gene controlling apomixs in allows more efficient early generation breeding and selection of sexual or apomictic forms of bluegrass.

Technical Abstract: The transfer of apomixis to various crop species has the potential to transform plant breeding, since it will allow new varieties to retain valuable traits thorough asexual reproduction. To increase the understanding of apomictic mechanisms in various species, a greater molecular understanding of apomixis is fundamental. In previous research, a gene identified as APOSTART, appeared to be associated to the apomictic mode of reproduction in Poa pratensis. This research presents a significant effort aimed at clarifying its role in apomixis. In situ hybridization studies indicated that PpAPOSTART is expressed in reproductive tissues from pre-meiosis to embryo development. APOSTART was also expressed early in a few nucellar cells of apomictic Poa pratensis individuals, possibly switching from a somatic to a reproductive cell form as understood in aposporic apomictics. Out of 13 evaluated APOSTART members, only one, APOSTART_6, was specifically expressed in the flower tissue. APOSTART_6 also exhibited delayed expression in apomictic genotypes when compared with sexual types. An APO-SCAR (Apomictic - Sequence Characterized Amplified Region) derived from the APOSTART_6 sequence was generated and observed to clearly discriminate between apomictic and sexual genotypes of Poa sp. The APO-SCAR marker studies and performed qPCR analysis, suggest APOSTART 6 to be the candidate gene controlling apomixes in P. pratensis.