Transient expression of a green fluorescent protein in tobacco and maize chloroplast

BACKGROUND: Maize is one of the most important crops worldwide and has been a target of nuclear-based transformation biotechnology to improve it and satisfy the food demand of the ever-growing global population. However, the maize plastid transformation has not been accomplished due to the recalcitrant condition of the crop. RESULTS: In this study, we constructed two different vectors with homologous recombination sequences from maize (Zea mays var. LPC13) and grass (Bouteloua gracilis var. ex Steud) (pZmcpGFP and pBgcpGFP, respectively). Both vectors were designed to integrate into rrn23S/rrn16S from an inverted repeat region in the chloroplast genome. Moreover, the vector had the mgfp5 gene driven by Prrn, a leader sequence of the atpB gene and a terminator sequence from the rbcL gene. Also, constructs have an hph gene as a selection marker gene driven by Prrn, a leader sequence from rbcL gene and a terminator sequence from the rbcL gene. Explants of maize, tobacco and Escherichia coli cells were transformed with both vectors to evaluate the transitory expression­an exhibition of green and red fluorescent light under epifluorescence microscopy. These results showed that both vectors were expressed; the reporter gene in all three organisms confirmed the capacity of the vectors to express genes in the cell compartments. CONCLUSIONS: This paper is the first report of transient expression of GFP in maize embryos and offers new information for genetically improving recalcitrant crops; it also opens new possibilities for the improvement in maize chloroplast transformation with these vectors.

Estudio del desarrollo, calidad de planta y acumulación de pigmentos en lígulas de tagetes erecta l: expuestas a dos intensidades de luz / Study of development, quality of plant and accumulation of pigments in ligules of tagetes erecta l: exposed to two light intensities

The carotenoids are photosensitive pigments during photosynthesis. The objective of this work was to study the effect on development and accumulation of carotenoids in ligules of Tagetes erecta exposed under two different lighting ambient (with mesh and without mesh of 50 percent). The plant development was evaluated measuring the height of the plant, number of floral buds, the ligules diameter. In adition, the quantification and identification of carotenoids from ligules was done by HPLC. The results showed significant differences (p<0.05) in the height of the plant, number of floral buds and ligules diameter of T. erecta. The group grown without mesh received greater UV radiation and different temperature, that under a mesh. The first conditions lead to a reduction of the ligules diameter and total content of xanthophylls (lutein and zeaxanthin). The plastids ultrastructure in the cells of T. erecta developed with mesh showed the greatest amount of thylakoid membranes and more conspicuous starch granules.

Los carotenoides son pigmentos fotosensibles frente a un exceso de intensidad luminosa durante el proceso de fotosíntesis. El objetivo de este trabajo fue el estudio del efecto en el desarrollo de la planta y la acumulación de carotenoides por la exposición a dos diferentes intensidades lumínicas (con y sin malla de sombra al 50 por ciento). Se evaluó el desarrollo de T. erecta en cuanto a la altura de la planta, número de botones florales y el diámetro de las lígulas. Adicionalmente, en las lígulas se cuantificaron e identificaron los carotenoides por HPLC. Los resultados mostraron diferencias significativas (p<0.05) en cuanto al desarrollo de las plantas expuestas a mayor radiación UV y temperatura, presentaron reducción del diámetro de las lígulas y disminución en el contenido de Xantófilas totales ( luteína y zeaxantina) con respecto a las cultivadas con malla,. La ultraestructura de los plastidios mostró mayor cantidad de membranas tilacoidales y gránulos de almidón más conspicuos en las células de las plantas de T erecta desarrolladas con malla.

Ultrastructural features of Mimulus aurantiacus (Scrophulariaceae) pollen tubes in vivo

The aim of this study is to give information on ultrastructure of in vivo pollen tubes of Mimulus aurantiacus which were collected from the Botanical Garden of the University of California at Berkeley. Materials were prepared according to electron microscopy methods and examined under Zeiss electron microscope. Four zones were examined in the pollen tubes of Mimulus aurantiacus. APICAL ZONE: Mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, dictyosomes and secretory vesicles were observed. SUBAPICAL ZONE: This area contained abundant rough endoplasmic reticulum and occasionally some smooth endoplasmic reticulum. The polysomes, mitochondria, proplastids that contain starch, small vacuoles and a few lipid bodies were detected. NUCLEAR ZONE: Both generative and vegetative cell nuclei lie in this zone. The vegetative cell nucleus was large and long. Rough endoplasmic reticulum, mitochondria, ribosomes, dictyosomes, and amyloplasts that are rich of starch were observed. VACUOLATION AND PLUG FORMATION ZONE: Cytoplasm of the tubes was full of large vacuoles. Few organelles such as mitochondria, dictyosome and rough endoplasmic reticulum were detected along their periphery.

O objetivo deste estudo é informar sobre a ultraestrutura de tubos de pólen de Mimulus aurantiacus in vivo coletados no "Botanical Garden" da Universidade da Califórnia em Berkeley. O material foi preparado de acordo com os métodos de microscopia eletrônica e examinado em microscópio eletrônico Zeiss. Quatro zonas dos tubos de pólen de Mimulus aurantiacus foram examinadas. ZONA APICAL: foram observados mitocôndrias, retículo endoplasmático liso; retículo endoplasmático rugoso, dictiossomos e vesículas secretoras. ZONA SUBAPICAL: esta área continha retículo endoplasmático rugoso em abundância e, ocasionalmente, algum retículo endoplasmático liso. Foram detectados polissomos, mitocôndrias, proplastídeos que contêm amido, pequenos vacúolos e alguns corpos lipídicos. ZONA NUCLEAR: nesta área, existem tanto núcleos de células geradoras como vegetativas. O núcleo de célula vegetativa é grande e longo. Foram observados retículo endoplasmático rugoso, mitocôndria, ribossomos, dictiossomos e amiloplastos ricos em amido. ZONA DE VACUOLIZAÇÃO E DE FORMAÇÃO DE "PLUG": o citoplasma dos tubos estava cheio de grandes vacúolos. Algumas organelas como mitocôndria, dictiossomo e retículo endoplasmático rugoso foram detectadas em toda a periferia desta área.

Fine structural study of the red seaweed Gymnogongrus torulosus (Phyllophoraceae, Rhodophyta)

The present study analyzed several characters of the red seaweed Gymnogongrus torulosus, such as cellular structure of the thallus, cuticle, pit plug and cell wall ultrastructure, and morphology of some organelles like plastids, Golgi bodies and mitochondria. Also, anomalous chloroplasts with thylakoid disorganization were found in medullary cells. The significance of this thylakoid disposition is still unclear. This is one of the first studies focused on the fine structure of a red alga recorded in Argentina.