An analysis of vascular system in the compound tendrilled afila leaf in Pisum sativum.

Recent work on the venation patterning and morphogenesis of leaf/leaflet has posed the question how different are these in tendrils, which are another type of vegetative lateral organ. Here, the venation patterns of leaflets, stipules and tendrils were compared in the model species, P. sativum. Unlike reticulated venation in leaflets and stipules, venation in tendrils comprised of one or more primary veins. A few secondaries were attached to a primary vein, mostly distally. Bilaterally symmetrical secondary veins were rare. The primary veins in tendrils were daughter strands from dichotomously divided mother veins in rachis, connected finally to vascular strands in stem. A tendril received primary vein from one or more mother strands. Some mother strands contributed primary veins to proximal, distal and terminal domain tendrils of af leaf. The tendrils shared the multi-primary vein character with stipules. Vein redundancy provided a mechanism for survival of tendril/leaf against injury to some of the veins/mother veins. The presence of aborted primary veins that did not reach apex, rows of cambium cells attached to primary vein(s) at apex, the pattern of attachment of primary veins to mother veins and cessation of vein growth in apical direction in aborted tendrils of af lld genotype indicated that the growth of primary veins and tendril was acropetal. Loss-of-function of AF extended the repression of TL and MFP genes on leaflet development from distal and apical domains to proximal domain of leaves in af mutants.

Estudios de transformación genética en arveja voluble cultivar Santa Isabel / Genetic transformation study in climbing pea Santa Isabel cultivar

Se probaron diferentes alternativas de transformación genética en arveja cultivar "Santa Isabel" con el fin de estudiar los factores que afectan el proceso. Se emplearon los métodos de infiltración mediante vacío, infección directa de explantes, transformación de polen, y microinyección de ovarios. La prueba histoquímica de expresión gus fue escogida como método de análisis en la determinación de transformantes positivos. Con las metodologías empleadas se detectaron puntos azules en el tejido vegetal, lo cual indica la expresión transitoria del transgen en los explantes utilizados. Los resultados obtenidos sugieren que la transformación genética en arveja cultivada en Colombia puede ser utilizada para la introducción de genes de interés como apoyo a los procesos de mejoramiento genético.

Different genetic transformation alternatives were tested in pea, "Santa Isabel" cultivar, with the purpose of studying the factors that affect the process. The methods of infiltration with vacuum, direct infection of the explants, pollen transformation and ovary microinjection were used. The hystochemical test of the gus expression was chosen as analysis method in the determination of positive transformants. With the used methodologies, blue spots in the plant tissue were detected, which indicates transient expression of the transgene in utilized explants. The obtained results suggest that the genetic transformation in pea genotypes planted in Colombia can be utilized for the introduction of genes of interest as support to genetic improvement.

Interaction between cochleata and stipule-reduced mutations results in exstipulate hypertrophied leaves in Pisum sativum L.

In the wild type P. sativum, each of the adult plant stem nodes, bears a pair of sessile foliaceous stipules and a petiolated unipinnately compound leaf of 4 to 6 leaflets and 7-9 tendrils. The stipule-reduced (st) and cochleata (coch) single null mutants and coch st double null mutant differ fom the wild type in respectively having sessile stipules of much reduced size, petiolated simple and/or compound leaf-like stipules and no stipules. It is also known that coch leaves are somewhat bigger than st and wild type leaves. Here, pleiotropic phenotype of coch st double mutant was investigated. The morphologies of stipules and leaf were quantified in the field grown plants and microcultured shoots, latter in the presence and absence of gibberellic acid and N-1-naphthylphthalamic acid. The observations showed that as compared to the corresponding plants or shoots of COCH ST (WT) genotype, (a) coch st plants bore leaves in which all the organs were hypertrophied; (b) full complement of leaflets and 3-5 tendrils were formed on leaf; (c) the microcultured coch st shoots were taller despite lower number of nodes, and (d) they also produced leaves in which all the organs were bigger and the ratio of leaflets/tendrils was higher. It was concluded that in coch st double mutant (a) ST function is essential for stipule primordium differentiation, in the absence of COCH function and (b) absence of negative feedback loops between simple stipules and compound leaf for metabolite utilization allows hypertrophied growth in leaves.

The lld mutation in Pisum sativum used as a genetic tool to discern the plant leaflet/leaf developmental process.

Leaves of P. sativum the double mutant genotype tendril-less (tl) leaflet-development (lld), due to the action of lld mutation, produce many leaflets that are aborted at different stages of development. Morphological, vein pattern and histological observations showed that aborted leaflets became cup/bell/trumpet (cup) shaped because of segmental differentiation in the leaflet primordium. Cup’s inside lamina surface was adaxial and outer surfaces of cup and its stem were abaxial. The lld cups were phenotypically homologous to aborted leaves described in Arabidopsis thaliana mutants, angustifolia and those which underexpressed the HD-ZIP III proteins. Leaflet primordium was found to grow and establish three dimensional polarities apex-downwards. Primordium produced lateral outgrowth on one side of midvein. Differentiation, in the outgrowth, of secondary veins, whose xylem tissues faced each other, established the adaxial-abaxial polarity. Lateral outgrowth then developed a cavity which got bounded by future adaxial epidermis. Further growth, veinlet formation, differentiation of palisade parenchyma and spongy parenchyma followed. Opening of lateral outgrowth at its outer midline produced a flat leaflet with lateral lamina spans. The structural and functional correspondence between leaflet and simple leaves suggested commonality between leaf and leaflet development mechanisms. A molecular model for the lld led leaflet abortion was also provided.

Effects of fly ash, Pseudomonas striata and Rhizobium on the reproduction of nematode Meloidogyne incognita and on the growth and transpiration of pea.

Glasshouse experiments were conducted twice to assess the ash amendments (0, 20, and 40% with soil), a phosphate solubilizing microorganism Pseudomonas striata and a root-nodule bacterium Rhizobium sp on the reproduction of root-knot nematode Meloidogyne incognita and on the growth and transpiration of pea. Amendments of fly ash with soil had no effect on transpiration. However, M. incognita reduced the rate of transpiration from 1st week onward after inoculation while inoculation of Rhizobium sp and P. striata increased transpiration from 1st week onward after their inoculation both in nematode inoculated and uninoculated plants. Increase in transpiration was greater when both organisms were inoculated together. Addition of 20 and 40% fly ash with soil was beneficial for plant growth both in nematode inoculated and uninoculated plants. Inoculation of above organisms also increases plant growth of nematode inoculated and uninoculated plants in different fly ash soil mixture but increase in growth was greater when both organisms were inoculated together. Use of 20% fly ash increased galling and nematode multiplication over plants grown in without fly ash while 40% fly ash had adverse effect on galling and nematode multiplication. Rhizobium sp had greater adverse effect on galling and nematode multiplication than P. striata. Use of both organisms together had greater adverse effect on galling and nematode multiplication than caused by either of them alone. Highest reduction in galling and nematode multiplication was observed when both organisms were used in 40% fly ash amended soil. However, highest transpiration was observed in plants without nematodes and inoculated with both organisms together both in with or without fly ash amended soil.