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Melatonin Modulates Plant Tolerance to Heavy Metal Stress: Morphological Responses to Molecular Mechanisms.
Hoque, MN, Tahjib-Ul-Arif, M, Hannan, A, Sultana, N, Akhter, S, Hasanuzzaman, M, Akter, F, Hossain, MS, Sayed, MA, Hasan, MT, et al
International journal of molecular sciences. 2021;(21)
Abstract
Heavy metal toxicity is one of the most devastating abiotic stresses. Heavy metals cause serious damage to plant growth and productivity, which is a major problem for sustainable agriculture. It adversely affects plant molecular physiology and biochemistry by generating osmotic stress, ionic imbalance, oxidative stress, membrane disorganization, cellular toxicity, and metabolic homeostasis. To improve and stimulate plant tolerance to heavy metal stress, the application of biostimulants can be an effective approach without threatening the ecosystem. Melatonin (N-acetyl-5-methoxytryptamine), a biostimulator, plant growth regulator, and antioxidant, promotes plant tolerance to heavy metal stress by improving redox and nutrient homeostasis, osmotic balance, and primary and secondary metabolism. It is important to perceive the complete and detailed regulatory mechanisms of exogenous and endogenous melatonin-mediated heavy metal-toxicity mitigation in plants to identify potential research gaps that should be addressed in the future. This review provides a novel insight to understand the multifunctional role of melatonin in reducing heavy metal stress and the underlying molecular mechanisms.
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Tolerance analysis of chloroplast OsCu/Zn-SOD overexpressing rice under NaCl and NaHCO3 stress.
Guan, Q, Liao, X, He, M, Li, X, Wang, Z, Ma, H, Yu, S, Liu, S
PloS one. 2017;(10):e0186052
Abstract
The 636-bp-long cDNA sequence of OsCu/Zn-SOD (AK059841) was cloned from Oryza sativa var. Longjing11 via reverse transcription polymerase chain reaction (RT-PCR). The encoded protein comprised of 211 amino acids is highly homologous to Cu/Zn-SOD proteins from tuscacera rice and millet. Quantitative RT-PCR revealed that in rice, the level of OsCu/Zn-SOD gene expression was lowest in roots and was highest in petals and during the S5 leaf stage. Moreover, the expression level of OsCu/Zn-SOD gene expression decreased during the L5 leaf stage to maturity. The level of OsCu/Zn-SOD gene expression, however, was increased under saline-sodic stress and NaHCO3 stress. Germination tests under 125, 150, and 175 mM NaCl revealed that OsCu/Zn-SOD-overexpressing lines performed better than the non-transgenic (NT) Longjing11 lines in terms of germination rate and height. Subjecting seedlings to NaHCO3 and water stress revealed that OsCu/Zn-SOD-overexpressing lines performed better than NT in terms of SOD activity, fresh weight, root length, and height. Under simulated NaHCO3 stress, OsCu/Zn-SOD-overexpressing lines performed better than NT in terms of survival rate (25.19% > 6.67%) and yield traits (average grain weight 20.6 > 18.15 g). This study showed that OsCu/Zn-SOD gene overexpression increases the detoxification capacity of reactive oxygen species in O. sativa and reduces salt-induced oxidative damage. We also revealed the regulatory mechanism of OsCu/Zn-SOD enzyme in saline-sodic stress resistance in O. sativa. Moreover, we provided an experimental foundation for studying the mechanism of OsCu/Zn-SOD enzymes in the chloroplast.
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Proteomic analysis of the function of sigma factor σ54 in Helicobacter pylori survival with nutrition deficiency stress in vitro.
Sun, Y, Liu, S, Li, W, Shan, Y, Li, X, Lu, X, Li, Y, Guo, Q, Zhou, Y, Jia, J
PloS one. 2013;(8):e72920
Abstract
H. pylori can survive under a nutrition-deficient environment. During infection and transmission, H. pylori is confronted with nutrient limitation and the bacterium requires rapid alteration in gene expression for survival under stress conditions. However, the mechanism underlining this regulation remains unknown. A previous study showed that σ(54) is an important regulation factor for H. pylori survival in the nutrition-deficient environment. Our results show that the expression of σ(54) (rpoN) is significantly induced in the stationary phase (nutrition deficiency) and the rpoN mutant showed a significantly lower viability than wild-type H. pylori in the late stationary phase. Thus, σ(54) is involved in H. pylori survival during nutrient limitation. We used comparative proteomics to analyze the protein differentiation between wild-type and rpoN mutant during the stationary phase. With depleted nutrients, σ(54) can slow the process of proliferation by negatively regulating genes involved in energy metabolism and biosynthesis and enhance stress-resistant ability by positively regulating genes involved in protein fate and redox reaction. Especially, NapA positively regulated by σ(54) plays an important function in H. pylori survival both in the stationary phase and in water, and the latter situation would be beneficial for bacterial in vitro transmission. Our investigations give new light on the adaptive regulation of H. pylori under stress conditions.
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Isolation and characterization of ethylene response factor family genes during development, ethylene regulation and stress treatments in papaya fruit.
Li, X, Zhu, X, Mao, J, Zou, Y, Fu, D, Chen, W, Lu, W
Plant physiology and biochemistry : PPB. 2013;:81-92
Abstract
Ethylene response factors (ERFs) play important roles in fruit development, ripening, defense responses and stress signaling pathways. After harvest, climacteric fruit such as papaya are subject to a range of problems associated with postharvest handling and storage treatments. There have been few attempts to evaluate the role of ERFs in fruit's responses to environmental stimuli. To investigate the transcriptional mechanisms underlying fruit developmental, ripening and stresses, we cloned four ERFs from papaya. The deduced amino acid sequence of CpERFs contained the conserved apetalous (AP2)/ERF domain, which shared high similarity with other reported AP2/ERF domains. The phylogeny, gene structures, and putatively conserved motifs in papaya ERF proteins were analyzed, and compared with those of Arabidopsis. Expression patterns of CpERFs were examined during fruit development, under 1-MCP treatment, ethephon treatment, biotic stress (temperature stress) and pathogen stress. CpERFs displayed differential expression patterns and expression levels under different experimental conditions. CpERF2 and CpERF3 showed a close association with fruit ripening and CpERFs had a high expression level in the earlier stages during the fruit development period. The expression of CpERFs strongly associated with stress response. These results support the role for papaya ERFs in transcriptional regulation of ripening-related or stress-respond genes and thus, in the regulation of papaya fruit-ripening processes and stress responses.