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4845. Tocopherols modulate leaf vein arrangement and composition without impacting photosynthesis

Creator:
Stewart, J. J., Adams, William W., Cohu, C. M., and Demmig-Adams, Barbara
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
vitamin E, foliar vasculature, leaf venation, vein density, vitamin E deficiency, xylem, 2, and 581
Language:
Multiple languages
Description:
Growth of the tocopherol-deficient vte1 mutant and Col-0 wild type of Arabidopsis thaliana in a sunlit glasshouse revealed both similarities and differences between genotypes. Photosynthetic capacity and leaf mesophyll features did not differ between mutant and wild type. Likewise, the total volume of water conduits (tracheary elements, TEs), sugar conduits (sieve elements, SEs), and sugar-loading cells (companion and phloem parenchyma cells) on a leaf area basis were unaffected by tocopherol deficiency. However, tocopherol deficiency yielded smaller and more numerous minor veins with fewer phloem cells and smaller TEs, resulting in greater ratios of TEs to SEs. The smaller TEs in the vte1 mutant may present a decreased risk for cavitation under high evaporative demand or in response to freezing. In turn, compensation for fewer phloem cells and smaller TEs by more numerous veins may bolster resistance to cavitation at no cost to photosynthetic capacity., J. J. Stewart, W. W. Adams, C. M. Cohu, B. Demmig-Adams., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4846. Tolerance mechanisms in Cassia alata exposed to cadmium toxicity - potential use for phytoremediation

Creator:
Silva, J. R. R., Fernandes, A. R., Silva Junior, M. L., Santos, C. R. C., and Lobato, A. K. S.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
těžké kovy, heavy metals, kadmium, fytoremediace, cadmium, phytoremediation, detoxifikace, výměna plynu, reaktivní formy kyslíku, remediace, detoxification, gas exchange, reactive oxygen species, remediation, Cassia alata, 2, and 581
Language:
Multiple languages
Description:
Cadmium is often detected in areas contaminated by heavy metals and the incidence of this element in dangerous concentrations has been increasing due to anthropogenic activities. The aim of this research was to determine Cd concentrations in tissues, quantify compounds, pigments and enzymes, and to evaluate the gas exchange. Our aim was also to identify components that can modify and contribute to tolerance of Cassia alata against Cd toxicity. We used five Cd concentrations (0, 22, 44, 88, and 132 μM) to validate our hypothesis. The Cd concentrations in tissues of C. alata plants increased significantly, compared with the control treatment, in the following graduated sequence: root > leaf > stem. Progressive enhancement in glutathione (GSH) was verified in plants treated with all Cd concentrations used, when compared with treatment without Cd. Antioxidant enzyme activities presented similar patterns with progressive enhancements, being a desirable characteristic for plants with a potential to hyperaccumulate Cd. Our results suggest that C. alata plants can be used for phytoremediation programs. Their defense mechanism is based on Cd accumulation in roots, coupled with increase in GSH and the efficient activity of antioxidant enzymes that contribute to minimize the oxidative stress and consequently improve the protection of the metabolic machinery., J. R. R. Silva, A. R. Fernandes, M. L. Silva Junior, C. R. C. Santos, A. K. S. Lobato., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4847. Tolerance of Mitragyna parvifolia (Roxb.) Korth. seedlings to NaCl salinity

Creator:
Bidalia, A., Hanief, M., and Rao, K. S.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fluorescence chlorofylu, výměna plynu, analýza růstu, efektivita využívání vody, dlouhodobá salinita, chlorophyll fluorescence, gas exchange, growth analysis, water-use efficiency, Kadam, long-term salinity, 2, and 581
Language:
Multiple languages
Description:
Increase in salinity is predicted to affect plant growth and survival in most arid and semiarid regions worldwide. Mitragyna parvifolia (Roxb.) Korth. is an important medicinal tree species distributed throughout the semiarid regions of India; however, it is facing a threat of its extinction in its natural habitat. We examined the effects of increasing NaCl salinity on two-month-old M. parvifolia seedlings grown in an environment-controlled chamber and exposed to soils of different electrical conductivity (EC) caused by NaCl [0-5 (control), 5-10, 10-15, 15-20, and 20-25 dS m-1)] for 85 days. Seedlings transferred to soil of EC >15 dS m-¹ did not survive beyond 1 week. Increase in the Na+ concentration negatively correlated with their height and positively correlated with their water-use efficiency (WUE). However, leaf area, net photosynthetic rate (PN), stomatal conductance, and transpiration rate showed varying correlations and an overall decrease in these parameters compared with the control. At EC of 10-15 dS m-1, the seedling height was reduced by 37% and PN was lowered by 50% compared with those of the control. An increase in the Na+/K+ ratio was observed with increasing salinity. The maximum quantum efficiency of PSII significantly decreased with increasing salinity compared with the control. Our results suggest that the increase in salinity reduced the overall performance of the M. parvifolia seedlings. However, the maintenance of WUE and maximum quantum efficiency of PSII might help M. parvifolia to tolerate NaCl salinity of 15 dS m-1., A. Bidalia, M. Hanief, K. S. Rao., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4848. Tolerance to water stress in tomato cultivars

Creator:
Srinivasa Rao, N. K. , Bhatt, R. M., and Sadashiva, A. T.
Format:
bez média and svazek
Type:
model:article and TEXT
Language:
Multiple languages
Description:
The effects of plant water stress imposed at vegetative, flowering, and fruiting stages of four cultivars of tomato (Lycopersicon esculentum Mill.) on net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), osmotic adjustment, and crop water stress index (CWSI) were investigated. Osmotic adjustment was the highest in cv. Arka Meghali, followed by cv. RFS-1. CWSI was lowest in cv. Arka Meghali and highest in cv. Pusa Ruby. Significant reduction in gs, E, and PN was observed in all the cultivars. The maximum reduction in E was observed in cv. Arka Saurabh during the fruiting stage (62.4 %) and maximum reduction in PN at the flowering stage in Pusa Ruby (53.1 %). Maximum PN was observed in Arka Meghali under water stress. The values of internal CO2 concentration (Ci) did not follow the decrease in gs which might be taken as an indication of mesophyll (non-stomatal) limitation to PN. Magnitude of PN decrease accompanying gs reductions varied in the four cultivars. Arka Meghali which had highest rate of gas exchange efficiency (PN/gs) under water deficits can be recommended for rainfed cultivation. and N. K. Srinivasa Rao, R. M. Bhatt, A. T. Sadashiva.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4849. Tolerance to waterlogging in young Euterpe oleracea plants

Creator:
Pereira, T. S., Lobato, A. K. S., Alves, G. A. R., Ferreira, R. N., Silva, O. N., Martins Filho, A. P. , Pereira, E. S., and Sampaio, L. S.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, Amazonka (řeka : oblast), Amazonas (Brazil), abiotic stress, açaí palm, ascorbate, glutathione, submergence, Euterpe oleracea, 2, and 581
Language:
Multiple languages
Description:
This study investigated whether gas exchange and the present content of antioxidant compounds can contribute to the survival of Euterpe oleracea plants in environments of frequent waterlogging. A factorial randomised, experimental design included two distinct water conditions (waterlogging and control) and five evaluation times (0, 6, 12, 18, and 24 d). Gasexchange parameters, leaf temperature, electrolyte leakage, and contents of antioxidant compounds were measured. Waterlogging did not promote significant alterations in net photosynthetic rate and transpiration, and stomatal conductance was reduced only after 18 d. Malondialdehyde and glutathione contents did not significantly change during waterlogging. Additionally, electrolyte leakage was significant only after 18 d of waterlogging. Thus, this study revealed that maintenance in gas exchange and antioxidant compounds might contribute to the survival of E. oleracea plants in environments exposed to waterlogging., T. S. Pereira, A. K. S. Lobato, G.A.R. Alves, R.N. Ferreira, O.N. Silva, A. P. Martins Filho, E.S. Pereira, L.S. Sampaio., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4850. Tolerance vs. avoidance: two strategies of soybean (Glycine max) seedlings in response to shade in intercropping

Creator:
Gong, W. Z., Jiang, C. D., Wu, Y. S., Chen, H. H., Liu, W. Y., and Yang, W. Y.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, sója luštinatá, photosynthesis, Glycine max, Sichuan (Čína : provincie), biomass partitioning, gas exchange, leaf structure, monocropping, palisade mesophyll, stem elongation, intercropping, 2, and 581
Language:
Multiple languages
Description:
Intercropping is a sustainable agricultural practice used worldwide for highly efficient utilization of resources. However, short crops often grow under the shade of the canopy of tall crops in intercropping systems. Plants evolved two main strategies to deal with shade: avoidance and tolerance. Soybean (Glycine max), a legume crop, is often planted in intercropping. But little is known about a strategy that soybean may employ to deal with shade at seedling stage. Therefore, we determined morphological and physiological traits related to shade tolerance and shade avoidance in seedlings of two varieties. Generally, both varieties showed similar shade tolerance traits, such as increased specific leaf area and chlorophyll (Chl) content, and reduced photosynthetic capacity and the Chl a/b ratio. The light-limiting environment eliminated the benefits of shade tolerance traits for the carbon gain, which led to similar real-time photosynthesis and biomass in intercropping. By contrast, two varieties expressed different changes in shade avoidance traits. The variety Guixia 3 exhibited clear preference of shade avoidance that resulted in a high main stem, hypocotyl elongation, and biomass allocation towards the stem. The variety Gongxuan 1 showed those traits less. We suggested that the genetic variation occurs within soybean, thus the shade avoidance related traits might be important for variety selection for intercropping. Hence, the evaluation of performance should focus on shade avoidance in soybean genotypes in future experiments., W. Z. Gong, C. D. Jiang, Y. S. Wu, H. H. Chen, W. Y. Liu, W. Y. Yang., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public