Diversification of SEC15a and SEC15b isoforms of an exocyst subunit in seed plants is manifested in their specific roles in Arabidopsis sporophyte and male gametophyte

0561590 - ÚEB 2023 RIV GB eng J - Článek v odborném periodiku
Batystová, Klára - Synek, Lukáš - Klejchová, Martina - Drdová, Edita - Sabol, P. - Potocký, Martin - Žárský, Viktor - Hála, Michal
Diversification of SEC15a and SEC15b isoforms of an exocyst subunit in seed plants is manifested in their specific roles in Arabidopsis sporophyte and male gametophyte.
Plant Journal. Roč. 110, č. 5 (2022), s. 1382-1396. ISSN 0960-7412. E-ISSN 1365-313X
Grant CEP: GA MŠMT(CZ) EF16_019/0000738; GA ČR(CZ) GC18-18290J; GA MŠMT(CZ) LM2018129
Institucionální podpora: RVO:61389030
Klíčová slova: Arabidopsis thaliana * cell expansion * exocyst * functional specialization * hypocotyl elongation * polarized secretion * pollen tube growth * sec15 * seed coat mucilage * seed plants
Obor OECD: Cell biology
Impakt faktor: 7.2, rok: 2022
Způsob publikování: Open access
https://doi.org/10.1111/tpj.15744

The exocyst complex is an octameric evolutionarily conserved tethering complex engaged in the regulation of polarized secretion in eukaryotic cells. Here, we focus on the systematic comparison of two isoforms of the SEC15 exocyst subunit, SEC15a and SEC15b. We infer that SEC15 gene duplication and diversification occurred in the common ancestor of seed plants (Spermatophytes). In Arabidopsis, SEC15a represents the main SEC15 isoform in the male gametophyte, and localizes to the pollen tube tip at the plasma membrane. Although pollen tubes of sec15a mutants are impaired, sporophytes show no phenotypic deviations. Conversely, SEC15b is the dominant isoform in the sporophyte and localizes to the plasma membrane in root and leaf cells. Loss-of-function sec15b mutants exhibit retarded elongation of hypocotyls and root hairs, a loss of apical dominance, dwarfed plant stature and reduced seed coat mucilage formation. Surprisingly, the sec15b mutants also exhibit compromised pollen tube elongation in vitro, despite its very low expression in pollen, suggesting a non-redundant role for the SEC15b isoform there. In pollen tubes, SEC15b localizes to distinct cytoplasmic structures. Reciprocally to this, SEC15a also functions in the sporophyte, where it accumulates at plasmodesmata. Importantly, although overexpressed SEC15a could fully complement the sec15b phenotypic deviations in the sporophyte, the pollen-specific overexpression of SEC15b was unable to fully compensate for the loss of SEC15a function in pollen. We conclude that the SEC15a and SEC15b isoforms evolved in seed plants, with SEC15a functioning mostly in pollen and SEC15b functioning mostly in the sporophyte.
Trvalý link: https://hdl.handle.net/11104/0334168