Roles of glycine betaine and proline in improving plant abiotic stress resistance

https://www.cell.com/trends/plant-science/pdf/S1360-1385(10)00032-4.pdf

WRKY transcription factors.

As the result of intensive research and breeding efforts over the last 20 years, the yield potential and yield quality of cereals have been greatly improved. Nowadays, yield safety has gained more importance because of the forecasted climatic changes. Drought and high temperature are especially considered as key stress factors with high potential impact on crop yield. Yield safety can only be improved if future breeding attempts will be based on the valuable new knowledge acquired on the processes determining plant development and its responses to stress. Plant stress responses are very complex. Interactions between plant structure, function and the environment need to be investigated at various phases of plant development at the organismal, cellular as well as molecular levels in order to obtain a full picture. The results achieved so far in this field indicate that various plant organs, in a definite hierarchy and in interaction with each other, are involved in determining crop yield under stress. Here we attempt to summarize the currently available information on cereal reproduction under drought and heat stress and to give an outlook towards potential strategies to improve yield safety in cereals.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3040.2007.01727.x

The effect of drought and heat stress on reproductive processes in cereals.

One-fifth of irrigated agriculture is adversely affected by soil salinity. Hence, developing salt-tolerant crops is essential for sustaining food production. Progress in breeding for salt-tolerant crops has been hampered by the lack of understanding of the molecular basis of salt tolerance and lack of availability of genes that confer salt tolerance. Genetic evidence suggests that perception of salt stress leads to a cytosolic calcium-signal that activates the calcium sensor protein SOS3. SOS3 binds to and activates a ser/thr protein kinase SOS2. The activated SOS2 kinase regulates activities of SOS1, a plasma membrane Na + /H + antiporter, and NHX1, a tonoplast Na + /H + anti-porter. This results in Na + efflux and vacuolar compartmentation. A putative osmosensory histidine kinase (AtHKI)-MAPK cascade probably regulates osmotic homeostasis and ROS scavenging. Osmotic stress and ABA (abscisic acid)-mediated regulation of LEA (late-embryogenesis-abundant)-type proteins also play important roles in plant salt tolerance. Genetic engineering of ion transporters and their regulators, and of the CBF (C-repeat-binding factor) regulons, holds promise for future development of salt-tolerant crops.

Understanding and Improving Salt Tolerance in Plants

Pigments are present in all living matter and provide attractive colors and play basic roles in the development of organisms. Human beings, like most animals, come in contact with their surroundings through color, and things can or cannot be acceptable based on their color characteristics. This review presents the basic information about pigments focusing attention on the natural ones; it emphasizes the principal plant pigments: carotenoids, anthocyanins, and betalains. Special considerations are given to their salient characteristics; to their biosynthesis, taking into account the biochemical and molecular biology information generated in their elucidation; and to the processing and stability properties of these compounds as food colorants.

Natural Pigments: Carotenoids, Anthocyanins, and Betalains — Characteristics, Biosynthesis, Processing, and Stability

An OsWRKY11 gene, which encodes a transcription factor with the WRKY domain, was identified as one of the genes that was induced by both heat shock and drought stresses in seedlings of rice (Oryza sativa L.). To determine if overexpression of OsWRKY11 confers heat and drought tolerance, OsWRKY11 cDNA was fused to the promoter of HSP101 of rice and introduced into a rice cultivar Sasanishiki. Overexpression of OsWRKY11 was induced by heat treatment. After heat pretreatment, the transgenic lines showed significant heat and drought tolerance, as indicated by the slower leaf-wilting and less-impaired survival rate of green parts of plants. They also showed significant desiccation tolerance, as indicated by the slower water loss in detached leaves. Our results indicate that the OsWRKY11 gene plays a role in heat and drought stress response and tolerance, and might be useful for improvement of stress tolerance.

Enhanced heat and drought tolerance in transgenic rice seedlings overexpressing OsWRKY11 under the control of HSP101 promoter

http://directory.umm.ac.id/Data%20Elmu/jurnal/P/PlantScience/PlantScience_Elsevier/Vol148.Issue2.2000/5192.pdf

Salt tolerance of transgenic rice overexpressing yeast mitochondrial Mn-SOD in chloroplasts

Accumulation of glycinebetaine in rice plants that overexpress choline monooxygenase from spinach and evaluation of their tolerance to abiotic stress.

Accumulation of glycinebetaine during cold acclimation and freezing tolerance in leaves of winter and spring barley plants

Exposure of 28-day-old rice seedlings for 6 days to 150 mm NaCl was found to induce drastic decreases in relative water contents, chlorophyll, and proteins in the leaves. This effect was largely prevened when before the exposure to NaCl the seedlings were treated for 4 days with 15 mm glycinebetaine. Although rice plants do not accumulate glycinebetaine endogenously, added glycinebetaine was found to be taken up by the roots and to accumulate in the leaves to reach a concentration of up to 5.0 μmol per gram fresh weight. The level is comparable with those of barley and wheat, which are well known glycinebetaine accumulators, under salt stress. The quantum yield of PSII was decreased by 27% under salt stress. This decrease was also largely prevented by glycinebetaine application.

Sachie Kishitani

Papers

Enhanced heat and drought tolerance in transgenic rice seedlings overexpressing OsWRKY11 under the control of HSP101 promoter

Salt tolerance of transgenic rice overexpressing yeast mitochondrial Mn-SOD in chloroplasts

Accumulation of glycinebetaine in rice plants that overexpress choline monooxygenase from spinach and evaluation of their tolerance to abiotic stress.

Accumulation of glycinebetaine during cold acclimation and freezing tolerance in leaves of winter and spring barley plants

Exogenous Glycinebetaine Accumulation and Increased Salt-tolerance in Rice Seedlings.