Exogenous Melatonin Improves the Growth of Rice Seedlings by Regulating Redox Balance and Ion Homeostasis Under Salt Stress

This study evaluated the effects of foliar spraying melatonin (MT) on the growth of salt-stressed rice. Seedlings were treated with 50 and 100 mM of NaCl and different concentrations of MT (25, 50, 100, 200, 300, and 400 μM) for 14 days. Different concentrations of MT could promote plant growth significantly under salt stress, particularly at concentrations of 200, 300, and 400 μM. A concentration of 200 μM MT was considered as optimal and used in a subsequent experiment on biomass, water content, antioxidation, mineral nutrition, salt absorption, and distribution of salt-stressed rice seedlings. Results showed that MT’s promoting effect on plant growth under salt stress was evident with time, particularly under high salt stress. MT improved the activities of antioxidant enzymes, reduced membrane lipid peroxidation, alleviated cell injury in plant leaves, and increased N content and Si accumulation in the leaves and roots under salt stress, particularly under high salinity. This compound also inhibited Na uptake and upward transport, but it promoted or maintained the uptake and upward transport of K and Ca in salt-stressed rice. Thus, MT improved the ion homeostasis of K/Na and Ca/Na in plants, particularly in the leaves. Foliar spraying of MT alleviated salt stress on rice by promoting nutrient accumulation or translocation, improving ion homeostasis, which is evident in the leaves, and consequently enhancing its salt resistance. The antioxidative improvement caused by MT might also be related to the improved ion homeostasis.

     

Association Between Pathophysiological Mechanisms of Diabetic Retinopathy and Parkinson’s Disease

Diabetic retinopathy, the most common complication of diabetes, is a neurodegenerative disease in the eye. And Parkinson's disease, affecting the health of 1–2% of people over 60 years old throughout the world, is the second largest neurodegenerative disease in the brain. As the understanding of diabetic retinopathy and Parkinson's disease deepens, the two diseases are found to show correlation in incidence, similarity in clinical presentation, and close association in pathophysiological mechanisms. To reveal the association between pathophysiological mechanisms of the two disease, in this review, the shared pathophysiological factors of diabetic retinopathy and Parkinson's disease are summarized and classified into dopaminergic system, circadian rhythm, neurotrophic factors, α-synuclein, and Wnt signaling pathways. Furthermore, similar and different mechanisms so far as the shared pathophysiological factors of the two disorders are discussed systematically. Finally, a brief summary and new perspectives are presented to provide new directions for further efforts on the association, exploration, and clinical prevention and treatment of diabetic retinopathy and Parkinson's disease.

     

GSK-3β inhibition protects human nucleus pulposus cell against oxidative stress-inducing apoptosis through mitochondrial pathway

Molecular Biology Reports - Oxidative stress in the intervertebral disc leads to nucleus pulposus (NP) degeneration by inducing cell apoptosis. However, the molecular mechanisms underlying this...     

Effect of autophagy on ferroptosis in foam cells via Nrf2

Molecular and Cellular Biochemistry - The progression of atherosclerotic plaque is accelerated by death of foam cells during the development of the plaque. There are several forms of foam cell...     

Hb New York,preliminary results concerning the hematologic characteristics and the effects on thalassemia

Molecular Biology Reports - The hematological phenotype and genotype analysis of hemoglobin New York (Hb New York) combined with α or β thalassemia has been rarely reported, and whether...     

Characterization of Agrobacterium-mediated co-transformation events in rice using green and red fluorescent proteins

Molecular Biology Reports - Biotechnologists seeking to develop marker-free transgenic plants have established co-transformation methods. For co-transformation using mixed Agrobacterium strains,...     

Auxin Resistant1 and PIN-FORMED2 Protect Lateral Root Formation in Arabidopsis under Iron Stress

A stunted root system is a significant symptom of iron (Fe) toxicity, yet little is known about the effects of excess Fe on lateral root (LR) development. In this work, we show that excess Fe has different effects on LR development in different portions of the Arabidopsis (Arabidopsis thaliana) root system and that inhibitory effects on the LR initiation are only seen in roots newly formed during excess Fe exposure. We show that root tip contact with Fe is both necessary and sufficient for LR inhibition and that the auxin, but not abscisic acid, pathway is engaged centrally in the initial stages of excess Fe exposure. Furthermore, Fe stress significantly reduced PIN-FORMED2 (PIN2)-green fluorescent protein (GFP) expression in root tips, and pin2-1 mutants exhibited significantly fewer LR initiation events under excess Fe than the wild type. Exogenous application of both Fe and glutathione together increased PIN2-GFP expression and the number of LR initiation events compared with Fe treatment alone. The ethylene inhibitor aminoethoxyvinyl-glycine intensified Fe-dependent inhibition of LR formation in the wild type, and this inhibition was significantly reduced in the ethylene overproduction mutant ethylene overproducer1-1. We show that Auxin Resistant1 (AUX1) is a critical component in the mediation of endogenous ethylene effects on LR formation under excess Fe stress. Our findings demonstrate the relationship between excess Fe-dependent PIN2 expression and LR formation and the potential role of AUX1 in ethylene-mediated LR tolerance and suggest that AUX1 and PIN2 protect LR formation in Arabidopsis during the early stages of Fe stress.Iron (Fe) is an essential trace element for plants (Pilon et al., 2009), and species differ greatly in how much Fe they require for optimal growth (Wheeler and Power, 1995; Batty and Younger, 2003). As Fe is frequently limiting, Fe deficiency is more commonly studied than toxicity arising from excess Fe exposure (Lei et al., 2014; Bashir et al., 2015; Briat et al., 2015). Fe is also a major focus for efforts in biofortification by targeting Fe transporters (Zhai et al., 2014; Pinto and Ferreira, 2015). However, the excessive presence of Fe in soils is equally common, in particular in soils characterized by low pH and hypoxic or anoxic conditions (Connolly and Guerinot, 2002). Toxicity arising from excess Fe exposure is recognized as one of the major plant diseases attributable to abiotic factors that impact the development and yield potential in the world’s leading cereal crops, rice (Oryza sativa) and wheat (Triticum aestivum; Becker and Asch, 2005; Khabaz-Saberi et al., 2012). Understanding the mechanisms underlying excess Fe toxicity is therefore essential.Plastic responses in the plant’s root system architecture are known to constitute a major mechanism by which plants cope with fluctuating environments. Lateral roots (LRs), which typically comprise the majority of the root system, contribute pivotally to nutrient acquisition from soil, and modulating LR development is a very important avoidance strategy for plants when confronted with unfavorable edaphic conditions, such as high salinity or heavy metals (Ivanov et al., 2003). In the case of excess exposure to Fe, stunting of the root system is among the chief symptoms of toxicity (Becker and Asch, 2005). However, while some information has been emerging on the primary root axis (Li et al., 2015), the specific role of the plant’s LR apparatus remains poorly studied. Yamauchi and Peng (1995) reported retardation of root growth and a reduction in LR length and number under excess Fe conditions. Recently, Reyt et al. (2015) showed that excess Fe had no significant effect on LR initiation in the LR branching zone and that ferritins play an important role in LR emergence under excess Fe in this portion of the root, although the authors had not investigated LR development in the root portions near the growing tip of the primary root. Because LR initiation is restricted to specific pericycle cell files adjacent to a xylem pole in the basal region of the meristem (De Smet et al., 2007; Fukaki and Tasaka, 2009), and LR formation in this new growing root portion may be more susceptible to stress stimuli, such as observed with exposure to high NH₄⁺ and salt (Duan et al., 2013; Li et al., 2013), it is reasonable to suggest that modulation of LR formation near the growing tip of the primary root is critical to the response to excess Fe stress.In Arabidopsis (Arabidopsis thaliana), the development of LRs proceeds through the following stages: lateral root primordia (LRP) initiation, establishment, emergence, activation into mature LRs, and final maintenance of LR elongation (Fukaki and Tasaka, 2009; Péret et al., 2009). The hormones abscisic acid (ABA) and auxin are important internal negative and positive regulators during LR development, respectively (Fukaki and Tasaka, 2009). ABA has been implicated in LRP emergence and meristem activation independent of auxin (De Smet et al., 2003). Auxin is an important internal positive regulator during LR development (Fukaki and Tasaka, 2009), and auxin transport is critical (Blilou et al., 2005). Mutants in auxin efflux carriers such as PIN-FORMED (PIN) and P-Glycoprotein show significant defects in LR formation (Fukaki and Tasaka, 2009; Péret et al., 2009). For example, LR initiation frequency was significantly reduced in pin2 and pin3 mutants (Dubrovsky et al., 2009), and PIN2 was also shown to be involved in exogenous and endogenous signal-mediated LR development (by brassinosteroid, jasmonate, and fungal challenge; Li et al., 2005; Felten et al., 2009; Sun et al., 2009). Similarly, Auxin Resistant1 (AUX1), an auxin influx carrier, also regulates LRP positioning and initiation (De Smet et al., 2007). While both AUX1 and PIN2 are required specifically for the basipetal transport of auxin through the outer root cell layers (Fukaki and Tasaka, 2009), PIN1 localized at the basal end of vascular cells is responsible for direct acropetal auxin flow in the root stele (Blilou et al., 2005). Recently, the roles of ethylene on LR development have also been highlighted, and the ethylene-mediated LR formation is dependent on the auxin pathway (Ivanchenko et al., 2008; Lewis et al., 2011). Ethylene treatment could mediate fluorescence of AUX1 and PIN2 fluorescent protein fusions at the root tip (Růzicka et al., 2007; Lewis et al., 2011). Although ABA, auxin, and ethylene signals have been implicated as important for LR development, it is not known whether and how the three hormones are involved in the response of LR formation to Fe stress.The previously described phenotypes and physiological processes related to Fe toxicity do not clarify the effect of excess Fe on LR formation. In this study, we employed the Arabidopsis wild type and ABA-, auxin-, and ethylene-related mutants to explore the LR formation response to Fe toxicity and to elucidate the roles of ABA, auxin, and ethylene. Potential mechanisms involved in the early stress response to Fe stress are discussed.