Ecological and phylogenetic constraints determine the stage of anthetic ovule development in orchids

Ovule abortion is a common phenomenon in plants that has an impact on seed production. Previous studies of ovule and female gametophyte (FG) development have mainly focused on angiosperms, especially in Arabidopsis thaliana. However, because it is difficult to acquire information about ovule development in gymnosperms, this remains unclear. Here, we investigated the transcriptomic data of natural ovule abortion mutants (female sterile line, STE) and the wild type (female fertile line, FER) of Pinus tabuliformis Carr. to evaluate the mechanism of ovule abortion during the process of free nuclear mitosis (FNM). Using single-molecule real-time (SMRT) sequencing and next-generation sequencing (NGS), 18 cDNA libraries via Illumina and two normalized libraries via PacBio, with a total of almost 400,000 reads, were obtained. Our analysis showed that the numbers of isoforms and alternative splicing (AS) patterns were significantly variable between FER and STE. The functional annotation results demonstrate that genes involved in the auxin response, energy metabolism, signal transduction, cell division, and stress response were differentially expressed in different lines. In particular, AUX/IAA, ARF2, SUS, and CYCB had significantly lower expression in STE, showing that auxin might be insufficient in STE, thus hindering nuclear division and influencing metabolism. Apoptosis in STE might also have affected the expression levels of these genes. To confirm the transcriptomic analysis results, nine pairs were confirmed by quantitative real-time PCR. Taken together, these results provide new insights into ovule abortion in gymnosperms and further reveal the regulatory mechanisms of ovule development.

Download Full-text

Orchid Bsister gene PeMADS28 displays conserved function in ovule integument development

Scientific Reports ◽

10.1038/s41598-020-79877-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ching-Yu Shen ◽

You-Yi Chen ◽

Ke-Wei Liu ◽

Hsiang-Chia Lu ◽

Song-Bin Chang ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Protein Interaction ◽

Ectopic Expression ◽

Flowering Plants ◽

Complementation Test ◽

Ovule Development ◽

Mads Box ◽

Temporal Expression ◽

Protein Protein Interaction ◽

Silique Length

AbstractThe ovules and egg cells are well developed to be fertilized at anthesis in many flowering plants. However, ovule development is triggered by pollination in most orchids. In this study, we characterized the function of a Bsister gene, named PeMADS28, isolated from Phalaenopsis equestris, the genome-sequenced orchid. Spatial and temporal expression analysis showed PeMADS28 predominantly expressed in ovules between 32 and 48 days after pollination, which synchronizes with integument development. Subcellular localization and protein–protein interaction analyses revealed that PeMADS28 could form a homodimer as well as heterodimers with D-class and E-class MADS-box proteins. In addition, ectopic expression of PeMADS28 in Arabidopsis thaliana induced small curled rosette leaves, short silique length and few seeds, similar to that with overexpression of other species’ Bsister genes in Arabidopsis. Furthermore, complementation test revealed that PeMADS28 could rescue the phenotype of the ABS/TT16 mutant. Together, these results indicate the conserved function of BsisterPeMADS28 associated with ovule integument development in orchid.

Download Full-text

The mac1 Gene: Controlling the Commitment to the Meiotic Pathway in Maize

Genetics ◽

10.1093/genetics/142.3.1009 ◽

1996 ◽

Vol 142 (3) ◽

pp. 1009-1020 ◽

Cited By ~ 3

Author(s):

William F Sheridan ◽

Nadezhda A Avalkina ◽

Ivan I Shamrov ◽

Tatyana B Batyea ◽

Inna N Golubovskaya

Keyword(s):

Female Gametophyte ◽

Embryo Sac ◽

Flowering Plants ◽

Normal Female ◽

Ovule Development ◽

Partial Sterility ◽

Embryo Sac Formation ◽

Female Gametophyte Development ◽

Normal Meiosis ◽

Pleiotropic Mutation

Abstract The switch from the vegetative to the reproductive pathway of development in flowering plants requires the commitment of the subepidermal cells of the ovules and anthers to enter the meiotic pathway. These cells, the hypodermal cells, either directly or indirectly form the archesporial cells that, in turn, differentiate into the megasporocytes and microsporocytes. We have isolated a recessive pleiotropic mutation that we have termed multiple archesporial cells1 (macl) and located it to the short arm of chromosome 10. Its cytological phenotype suggests that this locus plays an important role in the switch of the hypodermal cells from the vegetative to the meiotic (sporogenous) pathway in maize ovules. During normal ovule development in maize, only a single hypodermal cell develops into an archesporial cell and this differentiates into the single megasporocyte. In macl mutant ovules several hypodermal cells develop into archesporial cells, and the resulting megasporocytes undergo a normal meiosis. More than one megaspore survives in the tetrad and more than one embryo sac is formed in each ovule. Ears on mutant plants show partial sterility resulting from abnormalities in megaspore differentiation and embryo sac formation. The sporophytic expression of this gene is therefore also important for normal female gametophyte development.

Download Full-text

Prefertilization ovule development in Capsella: the dyad, tetrad, developing megaspore, and two-nucleate gametophyte

Canadian Journal of Botany ◽

10.1139/b86-114 ◽

1986 ◽

Vol 64 (4) ◽

pp. 875-884 ◽

Cited By ~ 13

Author(s):

Patricia Schulz ◽

William A. Jensen

Keyword(s):

Cell Wall ◽

Electron Microscope ◽

Acid Phosphatase ◽

De Novo ◽

Periodic Acid ◽

Aniline Blue ◽

Ovule Development ◽

Periodic Acid Schiff ◽

Fluorescent Material ◽

Autophagic Vacuoles

Ovules of Capsella bursa-pastoris at the dyad and tetrad stages of meiosis and at the megaspore and two-nucleate stages of the gametophyte were studied with the electron microscope. The cells of the dyad and tetrad are separated by aniline blue fluorescent cross walls and receive all types of organelles and autophagic vacuoles that were present in the meiocyte. Autophagic vacuoles enclose ribosomes and organelles and show reaction product for acid phosphatase. Autophagic vacuoles and some plastids are absorbed into the enlarging vacuoles of the growing megaspore. Other plastids appear to survive meiosis and there is no evidence for their de novo origin. Some mitochondria appear to degenerate in the enlarging megaspore but others look healthy and there is no evidence for the de novo origin of mitochondria. The nucleolus of the developing megaspore becomes very large and the cytoplasm is extremely dense with ribosomes. The cell wall is thickened by an electron-translucent, periodic acid – Schiff negative, aniline blue fluorescent material and contains plasmodesmata that link the megaspore with the nucellus. The plasmalemma of the growing megaspore produces microvilluslike extensions into this wall that disappear with the formation of the two-nucleate gametophyte. Plasmodesmata disappear from the cell wall at the four-nucleate stage.

Download Full-text

Taxon-Dependent Diversification of Life-History Traits and the Perception of Phylogenetic Constraints

Functional Ecology ◽

10.2307/2389415 ◽

1988 ◽

Vol 2 (3) ◽

pp. 417 ◽

Cited By ~ 39

Author(s):

E. M. Derrickson ◽

R. E. Ricklefs

Keyword(s):

Life History ◽

Life History Traits ◽

Phylogenetic Constraints

Download Full-text

Influence of phylogeny on the estimation of diet from dental morphology in the Carnivora

Paleobiology ◽

10.1017/pab.2021.37 ◽

2021 ◽

pp. 1-16

Author(s):

Samantha S. B. Hopkins ◽

Samantha A. Price ◽

Alec J. Chiono

Keyword(s):

Evolutionary History ◽

Morphological Data ◽

Evolutionary Constraints ◽

Dental Morphology ◽

Tooth Shape ◽

Fossil Mammals ◽

Phylogenetic Constraints ◽

Substantial Error ◽

Evolutionary Tempo And Mode ◽

Vertebrate Skeleton

Abstract Because teeth are the most easily preserved part of the vertebrate skeleton and are particularly morphologically variable in mammals, studies of fossil mammals rely heavily on dental morphology. Dental morphology is used both for systematics and phylogeny as well as for inferences about paleoecology, diet in particular. We analyze the influence of evolutionary history on our ability to reconstruct diet from dental morphology in the mammalian order Carnivora, and we find that much of our understanding of diet in carnivorans is dependent on the phylogenetic constraints on diet in this clade. Substantial error in estimating diet from dental morphology is present regardless of the morphological data used to make the inference, although more extensive morphological datasets are more accurate in predicting diet than more limited character sets. Unfortunately, including phylogeny in making dietary inferences actually decreases the accuracy of these predictions, showing that dietary predictions from morphology are substantially dependent on the evolutionary constraints on carnivore diet and tooth shape. The “evolutionary ratchet” that drives lineages of carnivorans to evolve greater degrees of hypercarnivory through time actually plays a role in allowing dietary inference from tooth shape, but consequently requires caution in interpreting dietary inference from the teeth fossil carnivores. These difficulties are another reminder of the differences in evolutionary tempo and mode between morphology and ecology.

Download Full-text