Highest Number Of Plant Species Research Articles

Phytochelatins are involved in differential arsenate tolerance in Holcus lanatus.

Arsenate tolerance is conferred by suppression of the high-affinity phosphate/arsenate uptake system, which greatly reduces arsenate influx in a number of higher plant species. Despite this suppressed uptake, arsenate-tolerant plants can still accumulate high levels of As over their lifetime, suggesting that constitutive detoxification mechanisms may be required. Phytochelatins are thiol-rich peptides, whose production is induced by a range of metals and metalloids including arsenate. This study provides evidence for the role of phytochelatins in the detoxification of arsenate in arsenate-tolerant Holcus lanatus. Elevated levels of phytochelatin were measured in plants with a range of tolerance to arsenate at equivalent levels of arsenate stress, measured as inhibition of root growth. The results suggest that arsenate tolerance in H. lanatus requires both adaptive suppression of the high-affinity phosphate uptake system and constitutive phytochelatin production.

A new class of Arabidopsis mutants with reduced hexadecatrienoic acid fatty acid levels.

Chloroplast glycerolipids in a number of higher-plant species, including Arabidopsis thaliana, are synthesized by two distinct pathways termed the prokaryotic and eukaryotic pathways. The molecules of galactolipids produced by the prokaryotic pathway contain substantial amounts of hexadecatrienoic acid fatty acid. Here we describe a new class of mutants, designated gly1, with reduced levels of hexadecatrienoic acid. Lipid fatty acid profiles indicated that gly1 mutants exhibited a reduced carbon flux through the prokaryotic pathway that was compensated for by an increased carbon flux through the eukaryotic pathway. Genetic and biochemical approaches revealed that the gly1 phenotype could not be explained by a deficiency in the enzymes of the prokaryotic pathway. The flux of fatty acids into the prokaryotic pathway is sensitive to changes in glycerol-3-phosphate (G3P) availability, and the chloroplast G3P pool can be increased by exogenous application of glycerol to leaves. Exogenous glycerol treatment of gly1 plants allowed chemical complementation of the mutant phenotype. These results are consistent with a mutant lesion affecting the G3P supply within the chloroplast. The gly1 mutants may therefore help in determining the pathway for synthesis of chloroplast G3P.

The Molecular Species of Diacylglycerol Precursors Used in Monogalactosyldiacylglycerol Biosynthesis in the Leaves of a Number of Higher Plant Species

The Molecular Species of Diacylglycerol Precursors Used in Monogalactosyldiacylglycerol Biosynthesis in the Leaves of a Number of Higher Plant Species

Möglichkeiten der Prognose synanthroper Pflanzenausbreitungen )

Summary The established aliens in regional floras share actually at about 5—25 % of the total number of higher plant species, in some urban and island floras more than 50 %. Most of the weeds could spread with trade and travel already during the last century. The influx of newcomers is now decreasing in some highly developed countries. This is to be seen from the years of the first record of all established aliens in Central Europe. A census of the neophytic Asteraceae of Europe and North America reveals that most of the species with a large native distribution have been already introduced into the other continent, whereas the species with a narrow native distribution generally don’t tend to synanthropic range expansion. With respect to the zonal position and the oceanity degrees the potential range in other continents resembles the native distribution. The limits of the potential range are usually reached by the newcomers within a time of some 100 or 200 years. The rapid spread often follows only after a lag-phase of some decennia. It is impossible to predict with certainty the degree of the anthropogenous enlargement of the potential range, but the general distribution character is usually preserved during the spread into the adjoining zones or oceanity degrees (as in the case of “equiformal progressive ranges”). The accelerated evolution of weeds by man’s impact on selection pressure and on possibilities of hybrididization is a further warning of an incautious prediction of range expansion of aliens.

Transgenic rye plants obtained by injecting DNA into young floral tillers

The most successful method currently used to produce transgenic plants is based on the ability of Argobacterium tumefaciens to infect a number of higher plant species and transfer a defined DNA fragment (T-DNA) to the genome of the infected cells1. This procedure cannot be used with the agriculturally important cereals, although preliminary data have suggested2 infection of maize seedlings by A. tumefaciens strains. Purified exogenous DNA can be taken up, integrated and expressed in cells of a variety of plant species including some cereals following direct gene transfer into isolated protoplasts3–7. However, although it is possible to grow isolated cereal protoplast into unorganized tissue (calli)5,7,8, only rice protoplasts have so far been shown to regenerate mature plants9–11. Here we report an alternative approach to transformation of cereal plants which does not involve tissue culture techniques.

Changes in the flora and vegetation of the coastal dunes of Voorne (The Netherlands) in relation to environmental changes

Ecologically the former isle of Voorne is very varied. This is reflected by an exceptionally high number of plant species and vegetation types. Many data regarding flora and vegetation have been collected during more than 25 years. A comparison of the early and the later data show that in this period many changes have taken place in flora and vegetation. The changes are partly the result of a natural development of the vegetation, but to a considerable extent they are due to human activities in the coastal area itself and in its surroundings. Examples of changes produced by natural developments and by human activities are given. The effects on flora and vegetation of the area are illustrated by comparing flora inventories, vegetation maps and permanent plot studies. In addition, the future development in the region which will strongly affect its natural value, is discussed.

Folk use of plant resource at Madi valley of Chitwan District, Nepal

The purpose of this study was to compare the use of the forest plant resources and folk nomenclature in the two communities of the Madi valley a Chitwan District. The information was collected during 2001 from 83 households in Chirauli and 57 households in Dhikurbari using semi-structured questionnaires. The folk nomenclature and relative importance of the plant species for medicine, firewood, fodder and timber differ in the two communities were recorded. A total of 128 species were reported in use by both communities, out of which 64 were common to both communities. The plant species used only in Chirauli accounted for 44 and that in Dhikurbari are 20. Tharu community of Chirauli reported higher number of plant species for medicinal, fodder and forage, fuel wood and timber than that of migrated people of Dhikurbari. 
 
 Banko Janakari Vol.15(2) 2005 pp28-33

Carboxydismutase Activity in Shade‐adapted and Sun‐adapted Species of Higher Plants

AbstractThe activity of the photosynthetic enzyme carboxydismutase (ribulose‐l,5‐diphosphate carboxylase) was measured in leaf extracts of a number of higher plant species from habitats with greatly contrasting light intensities. Plants occupying sunny habitats and capable of light saturated rates of photosynthesis several times higher than those growing in the deep shade of redwood forests also have a considerably higher carboxydismutase activity. Thus, when expressed on the basis of total chlorophyll or even fresh weight, the enzyme activity is several times greater among the sun than among the shade species.The comparatively low content of soluble protein in the shade plants indicates that their content of enzymes other than carboxydismutase also is low. Nevertheless, the activity of carboxydismutase even on the basis of soluble protein appears to be significantly higher in the sun than in the shade species.It is concluded that low carboxydismutase activity probably is one of the factors that limit the capacity for light saturated photosynthesis in the shade plants.