scholarly journals Suppression of Rice Cryptochrome 1b Decreases Both Melatonin and Expression of Brassinosteroid Biosynthetic Genes Resulting in Salt Tolerance

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1075
Author(s):  
Ok Jin Hwang ◽  
Kyoungwhan Back
Keyword(s):  
Rna Interference ◽  
Salt Tolerance ◽  
Blue Light ◽  
Transgenic Rice ◽  
Feedback Regulation ◽  
Wild Type ◽  
Rice Seedlings ◽  
Fresh Weight ◽  
Rice Plants ◽  
The Relationship

We investigated the relationship between the blue-light photoreceptor cryptochrome (CRY) and melatonin biosynthesis by generating RNA interference (RNAi) transgenic rice plants that suppress the cryptochrome 1b gene (CRY1b). The resulting CRY1b RNAi rice lines expressed less CRY1b mRNA, but not CRY1a or CRY2 mRNA, suggesting that the suppression is specific to CRY1b. The growth of CRY1b RNAi rice seedlings was enhanced under blue light compared to wild-type growth, providing phenotypic evidence for impaired CRY function. When these CRY1b RNAi rice plants were challenged with cadmium to induce melatonin, wild-type plants produced 100 ng/g fresh weight (FW) melatonin, whereas CRY1b RNAi lines produced 60 ng/g FW melatonin on average, indicating that melatonin biosynthesis requires the CRY photoreceptor. Due to possible feedback regulation, the expression of melatonin biosynthesis genes such as T5H, SNAT1, SNAT2, and COMT was elevated in the CRY1b RNAi lines compared to the wild-type plants. In addition, laminar angles decreased in the CRY1b RNAi lines via the suppression of brassinosteroid (BR) biosynthesis genes such as DWARF. The main cause of the BR decrease in the CRY1b RNAi lines seems to be the suppression of CRY rather than decreased melatonin because the melatonin decrease suppressed DWARF4 rather than DWARF.

Overexpression of plasma membrane Na+/H+ antiporter OsSOS1 gene improves salt tolerance in transgenic rice plants

2020 ◽  
Vol 57 (4) ◽  
pp. 277-287
Author(s):  
Sushma M Awaji ◽  
Prashantkumar S Hanjagi ◽  
Pushpa BN ◽  
Sashidhar VR
Keyword(s):  
Plasma Membrane ◽  
Salt Tolerance ◽  
Cell Viability ◽  
Chlorophyll Content ◽  
Transgenic Rice ◽  
Screening Test ◽  
Wild Type ◽  
Rice Plants ◽  
Transgenic Rice Plants ◽  
Salt Screening

Crop productivity is greatly affected by soil salinity; therefore, improvement in salinity tolerance of crops is a major goal in salt-tolerant breeding. The Salt Overly Sensitive (SOS) signal-transduction pathway plays a key role in ion homeostasis and salt tolerance in plants. In plants pumping of Na+ from the root cells is mediated by the plasma membrane Na+/H+ antiporter (SOS1) which plays important role in preventing the accumulation of toxic levels of Na+ in cytosol. In the present study, OsSOS1 (NHX7), gene was overexpressed in rice (var-Vikas) by Agrobacterium mediated In Planta transformation technique. To screen putative T1 plants for salt tolerance, stringent salt screening test was followed and root and shoot growth of transformants were used as selection criterion. Some of the putative transgenics showed significantly higher root growth compared to wild type. To confirm the presence of transgene in putative T1 transgenic plants, PCR based approach was followed using genomic DNA. The result showed that 16 % of the selected seedlings from the stringent salt screening test were PCR positives. Five selected lines were positive for RT-PCR analysis. Physiological studies such as chlorophyll content, membrane permeability, cell viability and sodium /potassium content analysis were also conducted to assess their levels of tolerance. Some of the T1 transformants showed lower percent reduction in chlorophyll content and less membrane leakage, higher cell viability and maintained higher K/Na ratio after NaCl treatment compared to wild type. These results clearly demonstrate that transgenic rice plants overexpressing OsSOS1 have better salt-tolerance. This could be attributed to extrusion of excess Na+ from cytosol into the apoplast and thereby reducing the toxic effects of Na+in the cell.

scholarly journals Enhanced Resistance to Seed-Transmitted Bacterial Diseases in Transgenic Rice Plants Overproducing an Oat Cell-Wall-Bound Thionin

2002 ◽  
Vol 15 (6) ◽  
pp. 515-521 ◽  
Author(s):  
Takayoshi Iwai ◽  
H. Kaku ◽  
R. Honkura ◽  
S. Nakamura ◽  
H. Ochiai ◽  
...  
Keyword(s):  
Transgenic Rice ◽  
Rice Seed ◽  
Wild Type ◽  
Rice Seedlings ◽  
Bacterial Diseases ◽  
Rice Plants ◽  
Enhanced Resistance ◽  
Etiolated Seedlings ◽  
High Level ◽  
Bacterial Attack

Bacterial attack is a serious agricultural problem for growth of rice seedlings in the nursery and field. The thionins purified from seed and etiolated seedlings of barley are known to have antimicrobial activity against necrotrophic pathogens; however, we found that no endogenous rice thionin genes alone are enough for resistance to two major seed-transmitted phytopathogenic bacteria, Burkholderia plantarii and B. glumae, although rice thionin genes constitutively expressed in coleoptile, the target organ of the bacteria. Thus, we isolated thionin genes from oat, one of which was overexpressed in rice. When wild-type rice seed were germinated with these bacteria, all seedlings were wilted with severe blight. In the seedling infected with B. plantarii, bacterial staining was intensively marked around stomata and intercellular spaces. However, transgenic rice seedlings accumulating a high level of oat thionin in cell walls grew almost normally with bacterial staining only on the surface of stomata. These results indicate that the oat thionin effectively works in rice plants against bacterial attack.

scholarly journals Plant Hormone Metabolome and Transcriptome Analysis of Dwarf and Wild-type Banana

2021 ◽  
Author(s):  
Biao Deng ◽  
Xuan Wang ◽  
Xing Long ◽  
Ren Fang ◽  
Shuangyun Zhou ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Transcriptome Analysis ◽  
Regulatory Mechanism ◽  
Feedback Regulation ◽  
Wild Type ◽  
Hormone Levels ◽  
Transporter Protein ◽  
Repressor Proteins ◽  
Differential Gene ◽  
The Relationship

AbstractGibberellin (GA), auxin (IAA) and brassinosteroid (BR) are indispensable in the process of plant growth and development. Currently, research on the regulatory mechanism of phytohormones in banana dwarfism is mainly focused on GA, and few studies are focused on IAA and BR. In this study, we measured the contents of endogenous GA, IAA and BR and compared the transcriptomes of wild-type Williams banana and its dwarf mutant across five successive growth periods. We investigated the relationship between hormones and banana dwarfism and explored differential gene expression through transcriptome analysis, thus revealing the possible metabolic regulatory mechanism. We inferred a complex regulatory network of banana dwarfing. In terms of endogenous hormone levels, GA and IAA had significant effects on banana dwarfing, while BR had little effect. The key gene in GA biosynthesis of is GA2ox, and the key genes in IAA biosynthesis are TDC and YUCCA. The differential expression of these genes might be the main factor affecting hormone levels and plant height. In terms of hormone signal transduction, DELLA and AUX/IAA repressor proteins were the core regulators of GA and IAA, respectively. They inhibited the process of signal transduction and had feedback regulation on hormone levels. Finally, the transporter protein PIN, AUX1/LAX protein family and ABCB subfamily played supplementary roles in the transport of IAA. These results provide new insights into GA and IAA regulation of banana growth and a reliable foundation for the improvement of dwarf varieties.

Overproduction of Chloroplast Glyceraldehyde-3-Phosphate Dehydrogenase Improves Photosynthesis Slightly under Elevated [CO2] Conditions in Rice

2020 ◽  
Author(s):  
Yuji Suzuki ◽  
Keiki Ishiyama ◽  
Misaki Sugawara ◽  
Yuka Suzuki ◽  
Eri Kondo ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Elevated Co2 ◽  
Transgenic Rice ◽  
Starch Content ◽  
Co2 Assimilation ◽  
Wild Type ◽  
Rice Plants ◽  
Gapdh Activity ◽  
Low Co2 ◽  
Transgenic Rice Plants

Abstract Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) limits the regeneration of ribulose 1,5-bisphosphate (RuBP) in the Calvin–Benson cycle. However, it does not always limit the rate of CO2 assimilation. In the present study, the effects of overproduction of GAPDH on the rate of CO2 assimilation under elevated [CO2] conditions, where the capacity for RuBP regeneration limits photosynthesis, were examined in transgenic rice (Oryza sativa). GAPDH activity was increased to 3.2- and 4.5-fold of the wild-type levels by co-overexpression of the GAPDH genes, GAPA and GAPB, respectively. In the transgenic rice plants, the rate of CO2 assimilation under elevated [CO2] conditions increased by approximately 10%, whereas that under normal and low [CO2] conditions was not affected. These results indicate that overproduction of GAPDH is effective in improving photosynthesis under elevated [CO2] conditions, although its magnitude is relatively small. By contrast, biomass production of the transgenic rice plants was not greater than that of wild-type plants under elevated [CO2] conditions, although starch content tended to increase marginally.

scholarly journals Enhanced accumulation of gibberellins rendered rice seedlings sensitive to ammonium toxicity

2019 ◽  
Vol 71 (4) ◽  
pp. 1514-1526
Author(s):  
Baolan Wang ◽  
Haifang Wei ◽  
Hui Zhang ◽  
Wen-Hao Zhang
Keyword(s):  
Physiological Function ◽  
Wild Type ◽  
Rice Seedlings ◽  
Gene Encoding ◽  
Ammonium Toxicity ◽  
Rice Plants ◽  
Worldwide Phenomenon ◽  
Increased Sensitivity ◽  
Ga Biosynthesis

Abstract Ammonium (NH4+) phytotoxicity is a worldwide phenomenon, but the primary toxic mechanisms are still controversial. In the present study, we investigated the physiological function of gibberellins (GAs) in the response of rice plants to NH4+ toxicity and polyamine accumulation using GA biosynthesis-related rice mutants. Exposure to NH4+ significantly decreased GA4 production in shoots of wild-type (WT) plants. Both exogenous GA application to the WT and increases in endogenous GA levels in eui1 mutants rendered them more sensitive to NH4+ toxicity. In contrast, growth of sd1 GA-deficient mutants was more tolerant to NH4+ toxicity than that of their WT counterparts. The role of polyamines in GA-mediated NH4+ toxicity was evaluated using WT rice plants and their GA-related mutants. The eui1 mutants with GA overproduction displayed a higher endogenous putrescine (Put) accumulation than WT plants, leading to an enhanced Put/[spermidine (Spd)+spermine (Spm)] ratio in their shoots. In contrast, mutation of the SD1 gene encoding a defective enzyme in GA biosynthesis resulted in a significant increase in Spd and Spm production, and reduction in the Put/(Spd+Spm) ratio when exposed to a high NH4+ medium. Exogenous application of Put exacerbated symptoms associated with NH4+ toxicity in rice shoots, while the symptoms were alleviated by an inhibitor of Put biosynthesis. These findings highlight the involvement of GAs in NH4+ toxicity, and that GA-induced Put accumulation is responsible for the increased sensitivity to NH4+ toxicity in rice plants.

Overexpression of sedoheptulose-1,7-bisphosphatase enhances photosynthesis and growth under salt stress in transgenic rice plants

2007 ◽  
Vol 34 (9) ◽  
pp. 822 ◽  
Author(s):  
Lingling Feng ◽  
Yujun Han ◽  
Gai Liu ◽  
Baoguang An ◽  
Jing Yang ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Salt Stress ◽  
Transgenic Plants ◽  
Transgenic Rice ◽  
Calvin Cycle ◽  
Rice Cultivar ◽  
Wild Type ◽  
Bisphosphate Carboxylase ◽  
Rice Plants ◽  
Transgenic Rice Plants

Activity of the Calvin cycle enzyme sedoheptulose-1,7-bisphosphatase (SBPase; EC3.1.3.37) was increased in the transgenic rice cultivar zhonghua11 (Oryza sativa L. ssp. japonica) by overexpressing OsSbp cDNA from the rice cultivar 9311 (Oryza sativa ssp. indica). This genetic engineering enabled the transgenic plants to accumulate SBPase in chloroplasts and resulted in enhanced tolerance of transgenic rice plants to salt stress at the young seedlings stage. Moreover, CO2 assimilation in transgenic rice plants was significantly more tolerant to salt stress than in wild-type plants. The analysis of chlorophyll fluorescence and the activity of SBPase indicated that the enhancement of photosynthesis in salt stress was not related to the function of PSII but to the activity of SBPase. Western-blot analysis showed that salt stress led to the association of SBPase with the thylakoid membranes from the stroma fractions. However, this association was much more prominent in wild-type plants than in transgenic plants. Results suggested that under salt stress, SBPase maintained the activation of ribulose-1,5-bisphosphate carboxylase-oxygenase by providing more regeneration of the acceptor molecule ribulose-1,5-bisphosphate in the soluble stroma and by preventing the sequestration of Rubisco activase to the thylakoid membrane from the soluble stroma, and, thus, enhanced the tolerance of photosynthesis to salt stress. Results suggested that overexpression of SBPase was an effective method for enhanncing salt tolerance in rice.

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