The Role of APOSTART in Switching between Sexuality and Apomixis in Poa pratensis.

Gianpiero Marconi,Loriano Storchi,Lara Reale,Niccolò Terzaroli,Alessandro Marrone,Emidio Albertini,Domenico Aiello,Bryan Kindiger

doi:10.3390/genes11080941

Abstract

The production of seeds without sex is considered the holy grail of plant biology. 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. Therefore, a greater molecular understanding of apomixis is fundamental. In a previous work we identified a gene, namely APOSTART, that seemed to be involved in this asexual mode of reproduction, which is very common in Poa pratensis L., and here we present a detailed work aimed at clarifying its role in apomixis. In situ hybridization showed that PpAPOSTART is expressed in reproductive tissues from pre-meiosis to embryo development. Interestingly, it is expressed early in few nucellar cells of apomictic individuals possibly switching from a somatic to a reproductive cell as in aposporic apomixis. Moreover, out of 13 APOSTART members, we identified one, APOSTART_6, as specifically expressed in flower tissue. APOSTART_6 also exhibited delayed expression in apomictic genotypes when compared with sexual types. Most importantly, the SCAR (Sequence Characterized Amplified Region) derived from the APOSTART_6 sequence completely co-segregated with apomixis.

Highlights

Angiosperms reproduce primarily through sexual reproduction, in plants, this requires a series of developmental steps that culminate in the formation of the seed
Due to its START domain and putative involvement in apomixis, we named this gene APOSTART [14]. In this previous work we described the cloning of two APOSTART members (APOSTART_1 and APOSTART_2)
molecular dynamics (MD) simulations corresponding to 250 ns trajectories were performed for the 18 bound complexes; we found a substantial loss of secondary structure, mainly affecting the

Summary

Introduction

Angiosperms reproduce primarily through sexual reproduction, in plants, this requires a series of developmental steps that culminate in the formation of the seed. Meiosis and fertilization as the main signs of sexuality, secure the formation of genetically variable diploid progeny [1]. This is not the only way to produce seed. In an asexual mode of reproduction, namely various forms of apomixis [2], successful apomictic events typically silence sexual development within the same ovule, allowing for the generation of unreduced gametes [2]. The conversion of a sexual reproducing genotype to one that reproduces by apomixis would make it possible to fix the genotype of a superior plant variety selected for a particular environment or market niche, whereby the clonally

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Conclusion