A plant-specific TGS1 homolog influences gametophyte development in sexual tetraploid Paspalum notatum ovules
Aposporous apomictic plants form clonal maternal seeds by inducing the emergence of non-reduced (2n) embryo sacs in the ovule nucellus and the development of embryos by parthenogenesis. In previous work, we reported a plant-specific TRIMETHYLGUANOSINE SYNTHASE 1 (TGS1) gene (PN_TGS1-like) showing...
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| Autores principales: | , , , , , , , , , |
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| Formato: | Artículo |
| Lenguaje: | Inglés |
| Publicado: |
Universidad de Carolina del Norte
2024
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| Materias: | |
| Acceso en línea: | http://repositorio.unne.edu.ar/handle/123456789/56240 |
| Aporte de: |
| Sumario: | Aposporous apomictic plants form clonal maternal seeds by inducing the emergence of
non-reduced (2n) embryo sacs in the ovule nucellus and the development of embryos by
parthenogenesis. In previous work, we reported a plant-specific TRIMETHYLGUANOSINE
SYNTHASE 1 (TGS1) gene (PN_TGS1-like) showing expression levels positively
correlated with sexuality rates in facultative apomictic Paspalum notatum. PN_ TGS1-like
displayed contrasting in situ hybridization patterns in apomictic and sexual plant ovules
from premeiosis to anthesis. Here we transformed sexual P. notatum with a TGS1-like
antisense construction under a constitutive promoter, in order to produce lines with
reduced transcript representation. Antisense plants developed prominent trichomes on
the adaxial leaf surface, a trait absent from control genotypes. Reproductive development
analysis revealed occasional formation of twin ovules. While control individuals typically
displayed a single meiotic embryo sac per ovule, antisense lines showed 12.93–15.79%
of ovules bearing extra nuclei, which can be assigned to aposporous-like embryo sacs
(AES-like) or, alternatively, to gametophytes with a misguided cell fate development.
Moreover, around 8.42–9.52% of ovules showed what looked like a combination of
meiotic and aposporous-like sacs. Besides, 32.5% of ovules at early developmental
stages displayed nucellar cells with prominent nuclei resembling apospory initials (AIs),
which surrounded the megaspore mother cell (MMC) or the MMC-derived meiotic
products. Two or more concurrent meiosis events were never detected, which suggest a
non-reduced nature for the extra nuclei observed in the mature ovules, unless they were
generated by proliferation and misguided differentiation of the legitimate meiotic products.
The antisense lines produced a similar amount of viable even-sized pollen with respect to
control genotypes, and formed an equivalent full seed set (~9% of total seeds) after selfpollination.
Flow cytometry analyses of caryopses derived from antisense lines revealed
that all full seeds had originated from meiotic embryo sacs (i.e. by sexuality). A reduction of 25.55% in the germination percentage was detected when comparing antisense lines
with controls. Our results indicate that PN_ TGS1-like influences ovule, gametophyte and
possibly embryo development. |
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