Mixed-nitrogen nutrition-mediated enhancement of drought tolerance of rice seedlings associated with photosynthesis, hormone balance and carbohydrate partitioning

Mycorrhizas are known to improve host plant nutritional status as a consequence of water transport from the soil to the host plant through the external mycelium as a direct effect or improved host plant nutrition primarily, phosphorus as an indirect effect. The direct hyphal water transport is quantified to be meager and a major part of the benefits of mycorrhizal symbiosis is indirect and nutritionally related. In arid and semi-arid regions where drought occurrence is very frequent and soil moisture content is highly restricted, mycorrhizas can assist in exploiting the soil beyond the rhizosphere that helps the host plant to withstand drought stress conditions. The drought tolerance in mycorrhiza-inoculated plants is quite complex and such response is due to a series of processes such as improved nitrogen (N) availability in soils, extensive root surface area and cationic exchange capacity, collective N assimilatory pathways in plant-mycorrhizal system, luxuriant uptake of nutrients besides remobilization of nutrients to support grain growth. These physiological, biochemical, nutritional and morphological changes in the mycorrhizas associated host plants have contributed to the ability of the host plants to survive under limited water environments. Despite mycorrhiza-assisted and N nutritionally enabled host plant drought tolerance is evident, more research is required to gain insights into the mechanisms involved. This review highlights the role of mycorrhizas on N dynamics in the rhizosphere and enhanced host plant N nutrition that collectively contributes to the sustained crop productivity under drought stress conditions.

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Characteristics of Drought Tolerance in ppc Overexpressed Rice Seedlings

ACTA AGRONOMICA SINICA ◽

10.3724/sp.j.1006.2008.01220 ◽

2008 ◽

Vol 34 (7) ◽

pp. 1220-1226 ◽

Cited By ~ 5

Author(s):

Li-Feng FANG

Keyword(s):

Drought Tolerance ◽

Rice Seedlings

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Exogenous salicylic acid and hydrogen peroxide attenuate drought stress in rice

Plant Soil and Environment ◽

10.17221/472/2019-pse ◽

2020 ◽

Vol 66 (No. 1) ◽

pp. 7-13 ◽

Cited By ~ 22

Author(s):

Abdullah Al Mamun Sohag ◽

Md. Tahjib-Ul-Arif ◽

Marian Brestic ◽

Sonya Afrin ◽

Md. Arif Sakil ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Salicylic Acid ◽

Drought Stress ◽

Drought Tolerance ◽

Oxidative Damage ◽

Photosynthetic Pigments ◽

Oryza Sativa L ◽

Water Status ◽

Protective Effects ◽

Rice Seedlings

Hydrogen peroxide (H2O2) and salicylic acid (SA) exhibit protective effects against a wide array of stresses. In this study, we investigated the relative efficacy of exogenous H2O2 and SA in conferring drought tolerance in rice (Oryza sativa L.). The experiment was repeated two times, firstly in a hydroponic system and secondly in soil. The results revealed that drought hampered germination indices, seedling growth, photosynthetic pigments, and water content, whereas increased proline content. It also triggered higher H2O2 production and consequently elevated lipid peroxidation, which is a particular indication of oxidative damage. However, exogenous H2O2 or SA treatment effectively alleviated oxidative damage in rice seedlings both in hydroponic and soil systems via upregulating antioxidant enzymes. Nevertheless, regulation of proline level and augmentation of plant-water status were crucial to confer drought tolerance. Exogenous H2O2 or SA also protected photosynthetic pigments from oxidative damage that might help to maintain normal photosynthesis under drought. Besides, 5 mmol/L H2O2 and 0.5 or 1 mmol/L SA showed similar effectiveness on mitigating drought stress. Finally, our findings suggest that exogenous H2O2 or SA could evenly be effectual in the amending growth of rice seedlings under drought conditions.

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598 Drought Stress Affects Carbohydrate Partitioning in Three Species of Herbaceous Perennials

HortScience ◽

10.21273/hortsci.34.3.550b ◽

1999 ◽

Vol 34 (3) ◽

pp. 550B-550

Author(s):

Kelly J. Prevete ◽

R. Thomas Fernandez ◽

William B. Miller

Keyword(s):

Molecular Weight ◽

Drought Stress ◽

Drought Tolerance ◽

High Molecular Weight ◽

Leaf Tissue ◽

Low Molecular Weight ◽

Carbohydrate Partitioning ◽

Herbaceous Perennials ◽

Drought Tolerant ◽

Crown Tissue

Drought stress durations of 2, 4, and 6 days were imposed on Boltonia asteroides `Snowbank', Eupatorium rugosum, and Rudbeckia triloba to determine the effects on carbohydrate partitioning in the plant. Drought stress was imposed on 19 Sept. 1997 on 1.9-L containerized plants. Plants were planted in the field the day following release from stress. Crown and leaf samples of the three species were collected 21, 23, 25 Sept. 1997 and 30 Jan. and 4 May 1998 and were analyzed for low molecular weight sugars and fructans. The species differed in the time it took for longer chain fructans to break down to shorter chain fructans and low molecular weight sugars (glucose, fructose). The drought tolerant Boltonia and Rudbeckia had shifts from longer chain to shorter chain fructans by day 4 of stress. Boltonia had a change in carbohydrate partitioning in the leaf tissue, while Rudbeckia had a change in crown tissue carbohydrate partitioning. Eupatorium did not have a shift in longer chain fructans to shorter chain fructans in crown tissue until day six of stress. The slower shift from longer chain fructans to shorter chain fructans by Eupatorium, compared to Boltonia and Rudbeckia, could explain the lack of drought tolerance of Eupatorium. The shift from high molecular weight sugars to low molecular weight sugars suggests that the higher molecular weight sugars broke down to lower molecular weight sugars in response to drought stress.

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