AUTHOR=Fernández Helena , Grossmann Jonas , Gagliardini Valeria , Feito Isabel , Rivera Alejandro , Rodríguez Lucía , Quintanilla Luis G. , Quesada Víctor , Cañal Mª Jesús , Grossniklaus Ueli 

TITLE=Sexual and Apogamous Species of Woodferns Show Different Protein and Phytohormone Profiles

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.718932

DOI=10.3389/fpls.2021.718932

ISSN=1664-462X

ABSTRACT=<p>The gametophyte of ferns reproduces either by sexual or asexual means. In the latter, apogamy represents a peculiar case of apomixis, in which an embryo is formed from somatic cells. A proteomic and physiological approach was applied to the apogamous fern <italic>Dryopteris affinis</italic> ssp. <italic>affinis</italic> and its sexual relative <italic>D. oreades</italic>. The proteomic analysis compared apogamous vs. female gametophytes, whereas the phytohormone study included, in addition to females, three apogamous stages (filamentous, spatulate, and cordate). The proteomic profiles revealed a total of 879 proteins and, after annotation, different regulation was found in 206 proteins of <italic>D. affinis</italic> and 166 of its sexual counterpart. The proteins upregulated in <italic>D. affinis</italic> are mostly associated to protein metabolism (including folding, transport, and proteolysis), ribosome biogenesis, gene expression and translation, while in the sexual counterpart, they account largely for starch and sucrose metabolism, generation of energy and photosynthesis. Likewise, ultra-performance liquid chromatography-tandem spectrometry (UHPLC-MS/MS) was used to assess the levels of indol-3-acetic acid (IAA); the cytokinins: 6-benzylaminopurine (BA), trans-Zeatine (Z), trans-Zeatin riboside (ZR), dyhidrozeatine (DHZ), dyhidrozeatin riboside (DHZR), isopentenyl adenine (iP), isopentenyl adenosine (iPR), abscisic acid (ABA), the gibberellins GA<sub>3</sub> and GA<sub>4</sub>, salicylic acid (SA), and the brassinosteroids: brassinolide (BL) and castasterone (CS). IAA, the cytokinins Z, ZR, iPR, the gibberellin GA<sub>4</sub>, the brassinosteoids castasterone, and ABA accumulated more in the sexual gametophyte than in the apogamous one. When comparing the three apogamous stages, BA and SA peaked in filamentous, GA<sub>3</sub> and BL in spatulate and DHRZ in cordate gametophytes. The results point to the existence of large metabolic differences between apogamous and sexual gametophytes, and invite to consider the fern gametophyte as a good experimental system to deepen our understanding of plant reproduction.</p>