Search results for "Shoot"
showing 10 items of 298 documents
Ni2+ toxicity in rice: effect on membrane functionality and plant water content.
2007
The heavy metal nickel is an essential mineral trace nutrient found at low concentrations in most natural soils. However, it may reach toxic levels in certain areas and affect a number of biochemical and physiological processes in plants. Wilting and leaf necrosis have been described as typical visible symptoms of Ni(2+) toxicity. The plasma membrane (PM) of root cells constitutes the first barrier for the entry of heavy metals but also a target of their toxic action. This work studies the relationship between disturbances of membrane functionality and the development of the typical symptoms of Ni(2+) toxicity. Rice plants (Oryza sativa L. cv. Bahia) grown in nutrient medium containing 0.5m…
Drought tolerance of clonal Malus determined from measurements of stomatal conductance and leaf water potential.
2003
We examined tolerance to soil drying in clonally propagated apple (Malus domestica Borkh.) rootstocks used to control shoot growth of grafted scions. We measured leaf conductance to water vapor (g(L)) and leaf water potential (Psi(L)) in a range of potted, greenhouse-grown rootstocks (M9, M26, M27, MM111, AR69-7, AR295-6, AR360-19, AR486-1 and AR628-2) as the water supply was gradually reduced. Irrespective of the amount of available water, rootstocks that promoted scion shoot growth (M26 and MM111) generally had higher g(L) and more negative Psi(L) than rootstocks that restricted scion shoot growth (M27 and M9). After about 37 days of reduced water supply, there were significant decreases …
Effects of partial rootzone drying and rootstock vigour on growth and fruit quality of 'Pink Lady' apple trees in Mediterranean environments
2008
We investigated the effects of partial rootzone drying (PRD) and rootstock vigour on water relations, and vegetative and productive performance of ‘Pink Lady’ apple (Malus domestica Borkh.) trees in central Sicily. In a first field trial, trees on MM.106 rootstock were subjected to: Conventional irrigation (CI), maintaining soil moisture above 80% of field capacity; PRD irrigation, where only one alternated side of the rootzone received 50% of the CI irrigation water; and continuous deficit irrigation (DI), where 50% of the CI water was equally applied to both sides of the rootzone. In a second trial, trees on M.9 or MM.106 were subjected to CI and PRD irrigation. PRD reduced stomatal condu…
Short-term response to waterlogging in Quercus petraea and Quercus robur: A study of the root hydraulic responses and the transcriptional pattern of …
2015
International audience; We characterized the short-term response to waterlogging in Quercus petraea (Matt.) Liebl. and Quercus robur L. as the initial response towards their known long-term differences in tolerance to waterlogging. One-month old seedlings were subjected to hypoxic stress and leaf gas exchange, shoot water potential (Psi(s)) and root hydraulic conductivity (Lp(r)) were measured. In parallel, the expression of nine aquaporins (AQPs) along the primary root was analysed by quantitative RT-PCR. Results showed a similar reduction in net assimilation (A) and stomatal conductance (g(s)) for the two species. Notably, the response of Lpr differed temporally between the two species. Q…
Cryopreservation of Digitalis obscura selected genotypes by encapsulation-dehydration
2001
Shoot-tips from several genotypes of the cardenolide-producing perennial shrub Digitalis obscura L. were successfully cryopreserved using the encapsulation-dehydration technique. Precultivation on MS medium containing 0.5 M sucrose, followed by 2.5 h dehydration (final weight 30 %) induced shoot regrowth in 42 % of cryopreserved shoot-tips. Cold-hardening of the in vitro cultures before sucrose treatment dramatically increased shoot recovery up to 86 %. The optimized cryopreservation protocol was then employed using different shoot cultures from five D. obscura genotypes. Responses to cryopreservation depended mainly on the genotype, best results being obtained when shoot tips from HU3 and …
Direct Organogenesis from Cotyledons in Cultivars of Citrus clementina Hort. ex Tan
2011
An efficient protocol to induce shoot buds regeneration in Citrus clementina cultivars (“Monreal”, “SRA 63” and “SRA 64”) by direct organogenesis has been developed using cotyledons as explants. Cotyledons transversely cut in three segments and entire ones were cultured on Murashige and Skoog (1962) solidified medium containing vitamins, 500 mg·l−1 malt extract, 50 g·l−1 sucrose and supplemented with three different concentrations of BAP (8.8, 13.2 and 17.6 μM). In all three cultivars the entire cotyledons showed more shoot morphogenic potential than transversely cut ones and after 60 incubation days the optimum BAP concentration was 17.6 μM in “Monreal” (50% ± 2.89% of frequency regenerati…
Carbohydrate metabolism of vegetative and reproductive sinks in the late-maturing peach cultivar ‘Encore’
1999
Activities of NAD(+)-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX), sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI) in 'Encore' peach (Prunus persica L.) fruits and developing shoot tips were assayed during the growing season to determine whether carbohydrate metabolizing enzymes could serve as indicators of sink strength. In fruit flesh, SS activity was detected during Stage I of growth, when cells were actively dividing, and SDH activity was detected during Stage III, when cells were actively enlarging. Acid invertase activity was detected during Stage I and showed a closer correlation with relative increase in fruit weight during the growing season…
Cryopreservation of white mulberry (Morus alba L.) by encapsulation-dehydration and vitrification
2011
Shoot apices of in vitro-grown plantlets of white mulberry, Morus alba L. cv Florio, were cryopreserved using either encapsulation-dehydration or vitrification. For encapsulation-dehydration, alginate beads containing apices were dehydrated for 1, 3, 5 or 7 days in a liquid medium containing various sucrose concentrations (0.5, 0.75, 1.0 or 1.25 M). Bead desiccation was performed using silica gel for either 0, 4, 6, 8, 9 or 14 h. For vitrification, apices were directly immersed for either 5, 15, 30 or 60 min in a vitrification solution (PVS2). Following encapsulation-dehydration, treatment of alginate beads with 0.75 M sucrose was more effective in promoting re-growth of explants after imme…
Effect of drought on sorbitol and sucrose metabolism in sinks and sources of peach
2000
In peach (Prunus persica [L.] Batsch.), sorbitol and sucrose are the two main forms of photosynthetic and translocated carbon and may have different functions depending on the organ of utilization and its developmental stage. The role and interaction of sorbitol and sucrose metabolism was studied in mature leaves (source) and shoot tips (sinks) of'Nemaguard' peach under drought stress. Plants were irrigated daily at rates of 100, 67, and 33% of evapotranspiration (ET). The relative elongation rate (RER) of growing shoots was measured daily. In mature leaves, water potential (ψ w ), osmotic potential (ψ s ), sorbitol-6-phosphate dehydrogenase (S6PDH, EC 1.1.1.200), and sucrose-phosphate synt…
Activities of Sucrose and Sorbitol Metabolizing Enzymes in Vegetative Sinks of Peach and Correlation with Sink Growth Rate
1999
Terminal portions of `Flordaguard' peach roots [Prunus persica (L.) Batsch] were divided into six segments and the activities of NAD+-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX), sucrose synthase (SS), soluble acid invertase (AI), and soluble neutral invertase (NI) were measured in each segment 10, 15, and 20 days after seed germination. The same type of experiment was conducted with terminal portions of `Flordaguard' and `Nemaguard' peach shoots except that one of the six segments consisted of the leaflets surrounding the apex. Independent of the age of individual roots, activities of SDH and AI were consistently highest in the meristematic portion and decreased with tis…