Sistema Reproductivo de Trichloris (Poaceae, Chloridoideae, Chlorideae)

Abstract

Summary:Reproductive system of Trichloris (Poaceae, Chloridoideae, Chlorideae). Trichloris crinita and T. pluriflora are important native forage species with the potential to be domesticated and introduced to cultivation, but there is scarce basic information on their reproductive biology. The aim of this work was to determine the reproductive system of both plant species in populations coming from north-central Argentina. The following was proposed: 1) determine the reproductive system through the fruit/flower ratio under controlled pollination, 2) quantify the weight of the fruits produced by population under different treatments and 3) confirm or discard the presence of apomixis through embryological observations. In T. crinita, the average fruit/flower ratio was 92.4 ± 6.6%, while in T. pluriflora, it was 70.7 ± 9.9%. These results are consistent with self-compatible species, preferably self-pollinated ones. Embryo sac development indicates sexual origin of seeds in both species. Significant differences in the average weight of one hundred fruits among populations and treatments, in both species, were found. The fruits were lighter in self-pollination. The information presented is a contribution to the tasks of selection and introduction to the culture of both species as well as to the conservation and regeneration of the collected germplasm.Key words: Trichloris, Reproductive success, Self-pollination, Fruit weight.Resumen: Trichloris crinita y T. pluriflora constituyen importantes forrajeras nativas con potencialidades de ser domesticadas e introducidas al cultivo, pero es escasa la información básica sobre su biología reproductiva. El objetivo de este trabajo fue determinar el sistema reproductivo de ambas especies en poblaciones provenientes del centro-norte de Argentina. Se propuso: 1) establecer el sistema reproductivo a través de la relación fruto/flor en polinizaciones controladas, 2) cuantificar el peso de los frutos producidos, por población, bajo diferentes tratamientos y, 3) confirmar o descartar la presencia de apomixis a través de observaciones embriológicas. En T. crinita, la relación fruto/flor promedio fue de 92,4 ± 6,6%, mientras que en T. pluriflora, fue de 70,7 ± 9,9%. Estos resultados se corresponden con especies autocompatibles, preferentemente autógamas. El desarrollo del saco embrionario indica origen sexual de las semillas en ambas especies. Se hallaron diferencias significativas en el peso promedio de cien cariopsis entre poblaciones y entre tratamientos, en ambas especies. Los frutos fueron más livianos en autopolinización. La información que se presenta es un aporte a las tareas de selección e introducción al cultivo como también a la conservación y regeneración del germoplasma recolectado.Palabras clave: Trichloris, Éxito reproductivo, Autopolinización, Peso de frutos.

Exploiting genetic and physiological variation of the native forage grass Trichloris crinita for revegetation in arid and semi‐arid regions: An integrative review

“…Altogether, the above data from the recent studies of Gutiérrez et al. () and Kozub et al. () provide conclusive evidence that Trichloris crinita reproduces mainly—if not exclusively—by sexual reproduction, and it self‐compatible and autogamous.…”

“…The combined data from embryo sac and FCSS analyses, reported by Kozub et al (2017), conclusively demonstrated that T. crinita seeds develop sexually (i.e., through double fertilization). In addition, pollination experiments performed in both studies concluded that T. crinita is self-compatible, because all the plants analysed produced seeds under self-pollination conditions (Guti errez et al, 2016;Kozub et al, 2017). In these studies, self-pollination was ensured by isolating inflorescences in moderately transparent paper bags 2 days prior to anthesis.…”

“…Apomixis or autogamy was initially proposed as the species mode of reproduction based upon the recurrent observation that the entire progeny of a plant had the same phenotype as the mother plant (Cavagnaro et al, 2006). Very recently, Kozub et al (2017) and Guti errez, Richard, and Cerino (2016) T. crinita inflorescences collected at the beginning of emergence and observed that megasporogenesis takes place at this stage, and they described the morphology of the mature megagametophyte. Kozub et al (2017) analysed, cytologically, 1,400 ovules from 20 different T. crinita accessions, finding that all the accessions had a single megagametophyte per ovule and that the embryo sac was eight nucleate and consisted of seven cells: the egg cell and two synergids at the micropylar pole, the central cell (with two polar nuclei) and three antipodal cells at the chalazal pole.…”

“…Very recently, Kozub et al. () and Gutiérrez, Richard, and Cerino () determined that T. crinita reproduces by means of sexuality, being the species self‐compatible and autogamous. Sexuality was determined through embryological analyses in both studies.…”

“…Gutiérrez et al. () performed cytological observations in T. crinita inflorescences collected at the beginning of emergence and observed that megasporogenesis takes place at this stage, and they described the morphology of the mature megagametophyte. Kozub et al.…”