Natural leaf senescence: probed by chlorophyll fluorescence, CO2 photosynthetic rate and antioxidant enzyme activities during grain filling in different rice cultivars

AbstractExperiments were carried out on three bread wheat varieties, one barley and one durum wheat variety grown in pots in the phytotron and subjected to water withdrawal for 7 days during grain-filling. Leaf water loss, net assimilation rate and transpiration showed marked differences, allowing the genotypes to be ranked. Although the most resistant variety had the highest activity for ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and glutathione-S-transferase (GST), which did not rise further in response to drought and the most susceptible variety had the lowest values, which increased to the greatest extent under drought, the level of sensitivity could not be predicted for all the genotypes from the enzyme activity values alone. The largest increases were recorded for the APX, CAT and GR activities. In most genotypes the GR activity was correlated with that of GST, CAT and APX. Changes in the enzyme activities were observed after a decline in transpiration and photosynthesis. The range of soil moisture values over which the antioxidant enzyme activity levels remained relatively unchanged was a better indication of tolerance to drought than either basic or stress-induced activity levels.

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Differential modulation of photosynthesis, ROS and antioxidant enzyme activities in stress-sensitive and -tolerant rice cultivars during salinity and drought upon restriction of COX and AOX pathways of mitochondrial oxidative electron transport

Journal of Plant Physiology ◽

10.1016/j.jplph.2021.153583 ◽

2021 ◽

pp. 153583

Author(s):

Dinakar Challabathula ◽

Benedict Analin ◽

Akhil Mohanan ◽

Kavya Bakka

Keyword(s):

Electron Transport ◽

Antioxidant Enzyme ◽

Enzyme Activities ◽

Antioxidant Enzyme Activities ◽

Rice Cultivars ◽

Differential Modulation

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Seed Priming with Brassinosteroids Alleviates Chromium Stress in Rice Cultivars via Improving ROS Metabolism and Antioxidant Defense Response at Biochemical and Molecular Levels

Antioxidants ◽

10.3390/antiox10071089 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1089

Author(s):

Farwa Basit ◽

Min Chen ◽

Temoor Ahmed ◽

Muhammad Shahid ◽

Muhammad Noman ◽

...

Keyword(s):

Antioxidant Enzyme ◽

Enzyme Activities ◽

Dry Weight ◽

Seed Priming ◽

Cellular Damage ◽

Antioxidant Enzyme Activities ◽

Rice Cultivars ◽

Rice Plants ◽

Cr Toxicity ◽

Cr Uptake

This research was performed to explore the vital role of seed priming with a 0.01 µM concentration of brassinosteroids (EBL) to alleviate the adverse effects of Cr (100 µM) in two different rice cultivars. Seed priming with EBL significantly enhanced the germination attributes (germination percentage, germination energy, germination index, and vigor index, etc.), photosynthetic rate as well as plant growth (shoot and root length including the fresh and dry weight) under Cr toxicity as compared to the plants primed with water. Cr toxicity induced antioxidant enzyme activities (SOD, POD, CAT, and APX) and ROS level (MDA and H2O2 contents) in both rice cultivars; however, a larger increment was observed in YLY-689 (tolerant) than CY-927 (sensitive) cultivar. EBL application stimulatingly increased antioxidant enzyme activities to scavenge ROS production under Cr stress. The gene expression of SOD and POD in EBL-primed rice plants followed a similar increasing trend as observed in the case of enzymatic activities of SOD and POD compared to water-primed rice plants. Simultaneously, Cr uptake was observed to be significantly higher in the water-primed control compared to plants primed with EBL. Moreover, Cr uptake was significant in YLY-689 compared to CY-927. In ultra-structure studies, it was observed that EBL priming relieved the rice plants from sub-cellular damage. Conclusively, our research indicated that seed priming with EBL could be adopted as a promising strategy to enhance rice growth by copping the venomous effect of Cr.

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Physiological Aspects of Compatibility and Incompatibility in Grafted Cucumber Seedlings

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.140.4.299 ◽

2015 ◽

Vol 140 (4) ◽

pp. 299-307 ◽

Cited By ~ 10

Author(s):

Qing Xu ◽

Shi-Rong Guo ◽

He Li ◽

Nan-Shan Du ◽

Sheng Shu ◽

...

Keyword(s):

Chlorophyll Fluorescence ◽

Oxidative Damage ◽

Antioxidant Enzyme ◽

Cucumis Sativus ◽

Enzyme Activities ◽

Abiotic Stresses ◽

Early Stage ◽

Antioxidant Enzyme Activities ◽

Vegetable Crops ◽

Cucumber Seedlings

The use of grafted seedlings in vegetable crops has increased in recent years to enhance the resistance to biological and abiotic stresses, and improve yields. However, incompatibility restricts the wide application of grafting. In this study, two pumpkin (Cucurbita) cultivars, with great differences in grafting affinity and symbiotic affinity, were used as rootstocks and cucumber (Cucumis sativus) seedlings were used as the scion. The effects of compatibility or incompatibility on histological aspects, antioxidant enzyme activities, phenylpropanoid contents, and chlorophyll fluorescence were studied. The results showed that compatible graft combinations present a stronger resistance to the oxidative damage resulting from grafting and had relatively weak phenylpropanoid metabolisms. The results also indicated that the chlorophyll fluorescence levels of incompatible combinations were lower, except compared with the original fluorescence. Finally, a necrotic layer existed earlier in compatible graft combinations. These differences at the morphological, physiological, and cellular levels may govern compatibility and incompatibility, and may provide valuable information for determining the symbiotic affinity of grafted seedlings at an early stage.

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