Journal of applied botany 

About: Journal of applied botany is an academic journal. The journal publishes majorly in the area(s): Water content & Germination. It has an ISSN identifier of 0949-5460. Over the lifetime, 146 publications have been published receiving 2322 citations.

Protective role of selenium in plant subjected to severe UV irradiation stress

Abstract: Recently selenium (Se) has been found to increase the antioxidative capacity and stress-defending ability of plants and even to enhance the growth of plants subjected to short-term UV episodes. Based on these findings, this study was undertaken to investigate if these effects can be obtained also under severe irradiation stress. Lettuce (Lactuca sativa L.), grown without Se or at two Se addition levels (0.01 and 0.05 mg kg -1 soil) and without UV or subjected to prolonged UV episodes (UV-B and a small amount of UV-C), was monitored for 8 weeks at 1-week intervals using growth and physiological parameters. Electron micrographs revealed that young plants grown without UV used Se to build up energy reserves, which was reflected as increased shoot yields. UV stress caused structural changes and disorders in cells and it also diminished shoot yields. At a low stress level, the thickening of cell walls mechanically protected the cells, which was reflected as diminished lipid peroxidation. Under severe UV stress, lipid peroxidation markedly increased, and the protecting role of Se via enhanced antioxidative capacity became apparent. Selenium was able to promote the growth of the UV-stressed plants, presumably through protection of chloroplast enzymes. It also postponed the death of plants subjected to severe irradiation stress. At the higher addition level Se exerted a toxic effect, but it was alleviated by the UV irradiation episodes, which promoted plant growth.

Bioactive polyphenols: Their role in quality and storability of fruit and vegetables

Abstract: Phenolic compounds are plant secondary metabolites that are naturally present in essentially all plant material, including food products of plant origin. They are particularly prominent in fruit and vegetables where they are important in determining colour, appearance, flavour and taste. These compounds form one of the main classes of secondary metabolites, with a large range of structures: monomeric, dimeric and polymeric phenolics have been identified. Given a free choice the consumer selects foods with a low content of lignin (toughness) and/or tannin (astringency), but sometimes with a relatively high anthocyanin content (appearance and/or ripeness indicator). During the postharvest life of fruit and vegetables and the different technological treatments to which these plant tissues are submitted in order to extend their shelf life, some changes in secondary metabolism occur. These metabolic changes of phenolic compounds, often coupled with the activity of polyphenol oxidase, are responsible for some phenomena affecting the quality of stored plant commodities. In this connection two important aspects, related to the presence of phenolics, receiving increasing attention from biochemists, plant physiologists and food technologists, are the role of phenolics in browning reactions and the resistance mechanism against storage fungi. This paper emphasizes some aspects related to low temperature metabolism of endogenous phenolics in plant tissue under chill stress with reference to shelf life of cold stored fresh fruit and vegetables.

Pacispora, a new vesicular arbuscular mycorrhizal fungal genus in the Glomeromycetes

Abstract: A new genus in the fungal family Glomeraceae, order Glomerales of the Glomeromycetes class is described, named Pacispora. The type species is P. scintillans which, as P. dominikii and P. chimonobambusae, was formerly placed in the genus Glomus of the Glomeraceae. Two of the already known species are re-described in this paper, and four new species of the new genus are published herein: Pacispora franciscana, P. robigina, P coralloidea and P boliviana. Spores of the new genus are formed terminally on hyphae, a feature they share only with Glomus and Paraglomus. An inner, usually three-layered wall is present inside the spores, from which the spores germinate directly through the outer spore wall, which usually is also three-layered. This germination characteristic is shared with Scutellospora, Acaulospora and Entrophospora but not with Glomus and Paraglomus. The formation of vesicular arbuscular mycorrhiza - so far confirmed for two of the seven Pacispora spp. -, the staining characteristics of the root internal fungal structures and the features of the subtending hyphae of the spores are most similar to species of the genus Glomus. For these reasons, we currently suggest to include Pacispora into the Glomeraceae. The seven Pacispora spp. can morphologically be differentiated by the spore surface structure, the characteristics of the spore wall ornamentation, and by the spore color and spore size. An identification key is presented. Three of the Pacispora spp. were abundantly detected in the high altitudes of the Swiss Alps. However, the occurrence of this genus in temperate, mediterranean and tropical regions suggests that Pacispora is ubiquitous and adapted to many terrestrial environments.

Evidence of sodium toxicity for the vegetative growth of maize (Zea mays L.) during the first phase of salt stress

Abstract: Salt stress reduces plant growth, especially that of glycophytic plants such as maize (Zea mays L.). According to the two-phase model proposed by MUNNS (1993), the first phase of salt stress is caused by osmotic effects, which are postulated to be responsible for the growth reduction. In a second phase, Na + accumulates and becomes toxic. In this study, we tested this model for a relatively salt-resistant maize genotype (Pioneer 3906) with particular attention to possible ion-specific effects apart from the osmotic stress during the first phase of salt stress. We induced osmotic stress in hydroponic culture by application of 100 mM NaCI or by equivalent osmotic potential adjusted with polyethyleneglycol (PEG 6000). The growth of the 4 t h leaf 5, 7, and 9 d after stress application of both treatments was strongly reduced in comparison to their corresponding controls. This indicates a prevalence of osmotic stress in the first phase of growth reduction. In comparison to the PEG treatment, a significant reduction in leaf growth under NaCI treatment was observed, which reveals an additional ion effect. An experiment using various salt solutions (NaCI, Na 2 SO 4 and MgCl 2 ) with equivalent ion concentrations and identical osmotic potential adjusted with PEG identified Na + toxicity during the first phase of salt stress. In conclusion, we propose a modification of the two-phase model of salt stress for maize.