Search results for "plant physiology"
showing 10 items of 118 documents
Increased Auxin Content and Altered Auxin Response in Barley Necrotic Mutant nec1
2012
The role of hormone crosstalk in plant immunity is lately emerging as significant topic of plant physiology. Although crosstalk between salicylic acid and auxin affects plant disease resistance, molecular mechanisms of this process have not yet been uncovered in details. Mutations disrupting cyclic nucleotide-gated ion channel 4 (CNGC4) affect SA-mediated disease resistance in barley Hordeum vulgare and in A. thaliana. Significantly, decreased stomatal apertures of barley CNGC4 mutant nec1 and dwarfed stature of A. thaliana CNGC4 mutant dnd2 suggest that nonfunctional CNGC4 might be affecting also auxin signaling. Excised coleoptile elongation, stomatal conductance, and cell size measuremen…
Changes in pigmentation of phytoplankton species during growth and stationary phase — consequences for reliability of pigment-based methods of biomas…
1991
In applied water ecology several methods for estimating the biomass or activity of phytoplankton depend on the proportion of accessory pigments (xanthophylls) to chlorophyll a. Therefore, changes in pigmentation during growth and stationary phase were investigated in four different species (Amphidinium klebsii, Euglena gracilis, Prymnesium parvum, Cryptomonas ovata) typical representatives of the major algal groups. The ratios of the different xanthophylls to chlorophyll a depended not only on the growth phase, but also on the species. InAmphidinium andEuglena, the ratio of xanthophylls to chlorophyll rises continuously during the growth phase and declined during the stationary phase. InPry…
Potential use of new diphenylurea derivatives in micropropagation of Capparis spinosa L.
2011
A protocol for in vitro multiplication of caper (Capparis spinosa L. subsp. rupestris) from nodal segments collected from mature plants was developed. For shoot multiplication, one auxin (indol-3-butyric acid, IBA) and cytokinins of two different classes were used: the N6-substituted adenine derivatives 6-benzylamino purine (BAP), and the two synthetic phenylurea derivatives N-phenyl-N′-benzothiazol-6-ylurea (PBU) and N-phenyl-N′-(1,2,3-thidiazol-5-yl) urea (thidiazuron, TDZ). Maximum shoot production was achieved from explants cultured with the adeninic cytokinin BAP (4 μM) and the auxin IBA (0.5 μM). New shoots longer than 1 cm were used for rooting. To induce root formation, three auxins…
The influence of α-aminophosphonic acids on the activity of aminopeptidase from barley seeds—an approach to determine the enzyme specificity
2015
Inhibitory potencies of 24 α-aminophosphonic acids against barley seeds (Hordeum vulgare L.) metallo-aminopeptidase have been determined to evaluate structural requirements of this enzyme. The enzyme was sensitive mostly to the influence of phosphonic acid analogues of phenylalanine and its homologues, thus showing narrow specificity if compared with porcine aminopeptidases M1 and M17 and with Plasmodium aminopeptidase M17.
Studies on the Content of Free Amino Acids in Needles of Undamaged and Damaged Spruce Trees at a Natural Habitat
1990
Summary Measurements of the amino acids in needles of undamaged and damaged 90-year-old spruce trees ( Picea abies ) showed different patterns. During the summer months a reduction in total amino acid content of about 60 % was found. In autumn the content of total amino acids rose again. The courses of the single amino acids behave similarly to that of the total amino acids. Quantitatively, the main amino acids were GLU, ASP and GLN with about 37 %, 21 % and 10 %, respectively, followed by PRO, ALA and SER with about 3–4 % each. In the needles of healthy trees large variations in ARG content could be observed. These variations correlate neither with the damage degree of the trees nor with t…
The apparent loss of tissue culture competence during leaf differentiation in yams (Dioscorea bulbifera L.)
1993
Explants taken from the leaves of yams (Dioscorea bulbifera L.) at different stages of development were cultured in vitro on a checkerboard using various combinations and/or concentrations of auxin (2,4-d) and cytokinin (6-BAP). An addition of cytokinin to the culture media was not essential for callus induction from explants derived from young leaves in the very early stages of expansion. When the leaves expanded further they required cytokinin and the requirement increased considerably during expansion. Explants taken from fully expanded leaves were no longer able to proliferate, even when extremely high concentrations of cytokinins were applied. Callus grown from highly immature leaves w…
Plant regeneration from cultured leaves of Lavandula latifolia Medicus: Influence of growth regulators and illumination conditions
1989
Leaves were obtained from 4-week-old seedlings of Lavandula latifolia Medicus grown in vitro. Leaf explants were then cultured on MS medium supplemented with different concentrations and combinations of the auxins IAA or NAA with the cytokinin BA and maintained under three illumination conditions, 16h photoperiod, darkness or darkness followed by a photoperiod, to assess morphogenic responses. Irrespective of illumination conditions, bud regeneration was achieved only in media containing BA or BA/auxin combinations, with the best results being obtained in the presence of BA and 0.06 or 0.6 μM IAA or NAA. A photoperiod of 16h appeared to yield the best response in terms of bud regeneration p…
Factors affecting adventitious bud induction in Pinus elliottii (Engelm.) embryos cultured in vitro
1987
Embryos of slash pine (Pinus elliottii Engelm.) were induced to form adventitious buds when placed in culture on nutrient media supplemented with cytokinin. Buds were induced on media containing Risser & White major salts. The high content in nitrogen of Murashige & Skoog formulation seems to be deleterious for this in vitro system, since morphogenic responses were only promoted when nitrogen concentration was drastically reduced in the macronutrient formulation. Factors such as concentration of cytokinin (6-benzyladenine) and time and method of exposure (liquid or solid induction medium) strongly influenced bud formation and development. The greatest number of buds and shoots were obtained…
Pasaulē lielākā koka čiekuri Latvijas Universitātes Muzejā
2019
LU Muzeja Botānikas un mikoloģijas kolekcijas dāvinājumā no valodnieces Ievas Auziņas Szentivanyi saņēmušas 5 milzu mamutkoka (Sequoiadendron giganteum (Lindl.) J.Buchh.) čiekurus, 3 no kuriem savākti šīs sugas pārstāvja, pašlaik pasaulē lielākā koka pēc koksnes apjoma, Ģenerāļa Šermana (General Sherman), pakājē.
Resilience of hop (Humulus lupulus L.) to salinity, heat and drought stresses: A mini-review
2022
Over recent years, the cultivation of hops (Humulus lupulus L.) has spread widely in the Mediterranean, also affecting the southern regions of Spain and Italy with a typical semi-arid climate. Several and recent studies have investigated the responses of this species to the main abiotic stresses, which is an aspect of absolute relevance to the knowledge of the adaptive capacity of hops to the growing conditions of a new cultivation environment. Moreover, given the fact that hops’ phytochemical composition is determined primarily by genetic and environmental factors, and that the species is perennial, the lack of knowledge on the effects of abiotic stress could be reflected in subsequent yea…