Comparative analysis of molecular and morphological diversity in two diploid Paspalum species (Poaceae) with contrasting mating systems.

Interspecific comparison of two Paspalum species has demonstrated that mating systems (selfing and outcrossing) contribute to variation (genetically and morphologically) within species through similar but mutually exclusive processes. Mating systems play a key role in the genetic dynamics of populations. Studies show that populations of selfing plants have less genetic diversity than outcrossing plants.

Alternative Evolutionary Pathways in Involving Allotetraploidy, Sexuality, and Varied Mating Systems.

The genetic systems of species have not been extensively studied. We analyzed the ploidy, reproductive mode, mating system, and fertility of four species-, , , and . An analysis of 378 individuals from 20 populations of northeastern Argentina was conducted.

Variation of Residual Sexuality Rates along Reproductive Development in Apomictic Tetraploids of .

Most apomictic plants are facultative, maintaining the ability to reproduce sexually at different frequencies depending on the taxa, ploidy, and reproductive stage. In this context, species are good model systems for studies evaluating the varying levels of apomixis expression. We aimed to identify, in apomictic tetraploid species, the degree of apomixis and residual sexuality in three stages of reproductive development, and if their expression varies along them in order to predict their realized impact on the genetic diversity of future generations.

First Glimpse on Spring Starflower Domestication.

The cultivation and domestication of plants are human-driven processes that change the biology and attributes of a plant. is a bulbous geophyte known as Spring Starflower whose cultivation dates back to the first half of the 19th century. At least seven cultivars have been developed from natural stands.

Genomic, karyological and morphological changes of South American garlics (Ipheion) provide insights into mechanisms of speciation in the Pampean region.

Speciation proceeds through mechanisms that promote reproductive isolation and shape the extent of genetic variation in natural populations, and thus its study is essential to understand the evolutionary processes leading to increased biodiversity. Chromosomal rearrangements are known to facilitate reproductive isolation by hybrid sterility and favour speciation events. The genus Ipheion (Amaryllidaceae, Allioideae) is unique as its species exhibit a remarkable karyological variability but lack population-level genetic data.

Sexual modulation in a polyploid grass: a reproductive contest between environmentally inducible sexual and genetically dominant apomictic pathways.

In systems alternating between sexual and asexual reproduction, sex increases under unfavorable environmental conditions. In plants producing sexual and asexual (apomictic) seeds, studies on the influence of environmental factors on sex are equivocal. We used Paspalum intermedium to study environmental effects on the expression of sexual and apomictic developments, and on resulting reproductive fitness variables.

A novel indicator of karyotype evolution in the tribe Leucocoryneae (Allioideae, Amaryllidaceae).

The tribe Leucocoryneae is taxonomically and cytogenetically complex, mainly due to its extraordinary morphological and karyological variation. Robertsonian translocations had long been recognized as a central factor contributing to karyotype diversity within the Leucocoryneae, but so far no major tendency prevailing on the observed complexity of karyotype formula among species has been identified. The assessment of nuclear DNA contents by flow cytometry using propidium iodide in 23 species, representing all genera within the tribe, showed a monoploid genome size variation of 1Cx = 9.

Harnessing apomictic reproduction in grasses: what we have learned from Paspalum.

Background: Apomixis is an alternative route of plant reproduction that produces individuals genetically identical to the mother plant through seeds. Apomixis is desirable in agriculture, because it guarantees the perpetuation of superior genotypes (i.e.

Competition between meiotic and apomictic pathways during ovule and seed development results in clonality.

Meiotic and apomictic reproductive pathways develop simultaneously in facultative aposporous species, and compete to form a seed as a final goal. This developmental competition was evaluated in tetraploid genotypes of Paspalum malacophyllum in order to understand the low level of sexuality in facultative apomictic populations. Cyto-embryology on ovules, flow cytometry on seeds and progeny tests by DNA fingerprinting were used to measure the relative incidence of each meiotic or apomictic pathway along four different stages of the plant's life cycle, namely the beginning and end of gametogenesis, seed formation and adult offspring.

Chromosome studies in Orchidaceae from Argentina.

The center of diversity of Argentinean orchids is in the northeast region of the country. Chromosome numbers and karyotype features of 43 species belonging to 28 genera are presented here. Five chromosome records are the first ones at the genus level; these taxa are Aspidogyne kuckzinskii (2n = 42), Eurystyles actinosophila (2n = 56), Skeptrostachys paraguayensis (2n = 46), Stigmatosema polyaden (2n = 40) and Zygostates alleniana (2n = 54).

Segregation for sexual seed production in Paspalum as directed by male gametes of apomictic triploid plants.

Background And Aims: Gametophytic apomixis is regularly associated with polyploidy. It has been hypothesized that apomixis is not present in diploid plants because of a pleiotropic lethal effect associated with monoploid gametes. Rare apomictic triploid plants for Paspalum notatum and P.