Germination profiling of lentil genotypes subjected to salinity stress

• Salinity is one of the most severe environmental stresses, negatively affecting productivity of salt‐sensitive crop species. Given that germination is the most critical phase in the plant life cycle, the present study aimed to determine seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt‐tolerant lentil genotypes.
• The genetic material consisted of six lentil genotypes whose adaptation to various agroclimatic conditions is not well elucidated. Salinity stress was applied by addition of NaCl at three different levels of stress, while non‐stressed plants were included as controls. Evaluation of tolerance was performed on the basis of germination percentage, seed water absorbance, root and shoot length, seedling water content, seedling vigour index and number of seedlings with an abnormal phenotype.
• Overall, our findings revealed that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the level of stress applied. It is noteworthy, however, that genotypes responded differently to the varying salinity levels. In this context, Samos proved the most salt‐tolerant genotype, indicating its possible use for cultivation under stress conditions.
• In conclusion, the determination of seed germination and early growth potential may be exploited as an efficient strategy to reveal genetic variation in lentil germplasm of unknown tolerance to salinity stress. This approach allows selection of desirable genotypes at early growth stages, thus enabling more efficient application of various breeding methods to achieve stress‐tolerant lentil genotypes.

     

Protein catabolism in growing Bacillus megaterium during adaptation to salt stress

Elevated concentration of NaCl in liquid medium caused a concentration-dependent growth delay (adaptation lag) and decrease in the maximal growth rate of Bacillus megaterium. The adaptation to salt stress was accompanied by transformation of some otherwise stable (long-lived; LLP) cell proteins into quickly degraded (short-lived; SLP) ones. Exposure to the strongly growth-reducing 1 M NaCl increased the size of the SLP 'pool' of intracellular proteins from about 5 to about 15% of total protein. The major intracellular proteolytic capacity of B. megaterium is represented by intracellular serine proteinases (ISP). Paradoxically, their specific activity was lowered or masked during the adaptation phase marked by increased catabolism of short-lived and/or destabilized proteins by the stress. This documents that intracellular proteolytic activity cannot be a key regulator of protein catabolism during adaptation to stress.     

细胞程序性死亡在植物适应逆境中的意义

细胞程序性死亡是近年来生命科学的研究热点之一,它不仅在植物生长发育中起重要作用,而且与植物适应逆境也密切相关。本文就细胞程序性死亡在植物适应逆境中的重要作用进行了综述,以期对细胞程序性死亡的研究进一步深入和对植物适应逆境的潜力有新的认识。     

Rapid loss of stress resistance in Drosophila melanogaster under adaptation to laboratory culture

We investigate changes in resistance to desiccation and starvation during adaptation of Drosophila melanogaster to laboratory culture. We test the hypothesis that resistance to environmental stresses is lost under laboratory adaptation. For both traits, there was a rapid loss of resistance over a three-year period. The rapidity of the response suggested that mutation accumulation could not account for it. Rather, resistance to environmental stresses appeared to be lost as a correlated response to selection on another trait, such as early fertility, with which stress resistance is negatively genetically correlated. These results suggest that caution is needed when extrapolating from evolution of stress resistance in long-established laboratory stocks to patterns of responses and correlated responses in natural populations.     

Metabolic adaptation of Escherichia coli to long-term exposure to salt stress

The aim of this work was to understand the relevance of central carbon metabolism in salt stress adaptation of Escherichia coli. The cells were grown anaerobically in batch and chemostat reactors at different NaCl concentrations using glycerol as a carbon source. Enzyme activities of the main metabolic pathways, external metabolites, ATP level, NADH/NAD⁺ ratio, l-carnitine production and the expression level of the main genes related to stress response were used to characterize the metabolic state under the osmotic stress. The results provided the first experimental evidence of the important role played by central metabolism adaptation and cell survival after long-term exposure to salt stress. Increased glycolytic fluxes and higher production of fermentation products indicated the importance of energy metabolism. Carbon fluxes under stress conditions were controlled by the decrease in the isocitrate dehydrogenase/isocitrate lyase ratio and the phosphoenolpyruvate carboxykinase/phosphoenolpyruvate carboxylase ratio, and the increase in the phosphotransferase/acetyl-CoA synthetase ratio. Altogether, the results demonstrate that, under salt stress, E. coli enhances energy production by substrate-level phosphorylation (Pta–Ack pathway) and the anaplerotic function of the TCA cycle, in order to provide precursors for biosynthesis. The results are discussed in relation with the general stress response and metabolic adaptation of E. coli.     

海洋微藻对重金属镉胁迫的抗氧化应激适应性

近海海域重金属镉污染已成为全球性的环境灾难。镉对有机体的氧化应激胁迫是引发有机体毒害效应的关键原因。海洋微藻是海域生态系统中初级生产者,研究其抵抗镉氧化应激毒害的过程和机理对海洋生态学具有重要科学意义。海洋微藻在长期进化发展过程中,形成了耐受重金属镉毒害的生长适应性反应,抵抗镉氧化应激胁迫是海洋微藻减轻或消除镉毒害的关键所在。文章概述当前近海重金属镉的污染现状,归纳重金属镉对海洋微藻的氧化应激毒害效应,提出海洋微藻对镉胁迫的抗氧化应激适应性,简介几种典型的抗氧化应激酶类与非酶类物质,最后指出该领域的关键问题并进行展望。     

Oxidative stress tolerance in plants: Novel interplay between auxin and reactive oxygen species signaling

Biotic and abiotic stress conditions produce reactive oxygen species (ROS) in plants causing oxidative stress damage. At the same time, ROS have additional signaling roles in plant adaptation to the stress. It is not known how the two seemingly contrasting functional roles of ROS between oxidative damage to the cell and signaling for stress protection are balanced. Research suggests that the plant growth regulator auxin may be the connecting link regulating the level of ROS and directing its role in oxidative damage or signaling in plants under stress. The objective of this review is to highlight some of the recent research on how auxin’s role is intertwined to that of ROS, more specifically H₂O₂, in plant adaptation to oxidative stress conditions.     

Adaptation to ER stress as a driver of malignancy and resistance to therapy in human melanoma

Primary events in the development of melanoma are gradually being pieced together but a more complete picture of evolution of the disease requires additional understanding of secondary events consequent on initiation of the malignancy. Arguably, the most important driver of secondary events is signals resulting from induction of endoplasmic reticulum (ER) stress for example due to hypoglycaemia and anoxia. This may result in a variety of responses such as apoptosis, autophagy and senescence depending on the initiating event and cell type but most importantly it may result in progression of melanoma due to adaptation and selection of melanoma cells to ER stress. The following reviews what is known about the adaptive responses and how this information may provide new initiatives in treatment of the disease.     

Epigenetic responses to heat stress at different time scales and the involvement of small RNAs

The hypothesis that plants can benefit from a memory of past stress exposure has recently attracted a lot of attention. Here, we discuss two different examples of heat stress memory to elucidate the potential benefits that epigenetic responses may provide at both the level of acclimation of the individual plant and adaptation at a species-wide level. Specifically, we discuss how microRNAs regulate the heat stress memory and thereby increase survival upon a recurring heat stress. Secondly, we review how a prolonged heat stress in a small interfering RNA-deficient background induces retrotransposition that is transmitted to the next generation, thus creating genetic variation for natural selection to act on. Collectively, these studies reveal a crucial role of short RNAs in heat stress memory across different time scales.     

Lactobacillus,Bifidobacterium and Lactococcus response to environmental stress: Mechanisms and application of cross-protection to improve resistance against freeze-drying

The review deals with lactic acid bacteria in characterizing the stress adaptation with cross-protection effects, mainly associated with Lactobacillus, Bifidobacterium and Lactococcus. It focuses on adaptation and cross-protection in Lactobacillus, Bifidobacterium and Lactococcus, including heat shocking, cold stress, acid stress, osmotic stress, starvation effect, etc. Web of Science, Google Scholar, Science Direct, and PubMed databases were used for the systematic search of literature up to the year 2020. The literature suggests that a lower survival rate during freeze-drying is linked to environmental stress. Protective pretreatment under various mild stresses can be applied to lactic acid bacteria which may enhance resistance in a strain-dependent manner. We investigate the mechanism of damage and adaptation under various stresses including heat, cold, acidic, osmotic, starvation, oxidative and bile stress. Adaptive mechanisms include synthesis of stress-induced proteins, adjusting the composition of cell membrane fatty acids, accumulating compatible substances, etc. Next, we reveal the cross-protective effect of specific stress on the other environmental stresses. Freeze-drying is discussed from three perspectives including the regulation of membrane, accumulation of compatible solutes and the production of chaperones and stress-responsive proteases. The resistance of lactic acid bacteria against technological stress can be enhanced via cross-protection, which improves industrial efficiency concerning the survival of probiotics. However, the adaptive responses and cross-protection are strain-dependent and should be optimized case by case.     

Transient stress and stress enzyme responses have practical impacts on parameters of embryo development, from IVF to directed differentiation of stem cells

In this review, we discuss the expression, regulation, downstream mechanisms, and function of stress-induced stress enzymes in mammalian oocytes, peri-implantation embryos, and the stem cells derived from those embryos. Recent reports suggest that stress enzymes mediate developmental functions during early mammalian development, in addition to the homeostatic functions shared with somatic cells. Stress-induced enzymes appear to insure that necessary developmental events occur: many of these events may occur at a slower rate, although some may occur more rapidly. Developmental events induced by stress may be mediated by a single dominant enzyme, but there are examples of responses that require the integration of more than one stress enzyme. The discussion focuses on the consequences of stress as a function of duration and magnitude, and this includes an emerging understanding of the threshold levels of duration and magnitude that lead to pathology. Other topics discussed are the reversibility of the developmental as well as homeostatic consequences of stress, the further problems with readaptation after stress subsides, and the mechanisms and functions of stress enzymes during early mammalian development. The analyses are done with specific concern for their practical impact in assisted reproductive technology (ART) and stem cell technologies.     

Changes in the topological state of DNA duringEscherichia coli adaptation to oxidative stress under glucose starvation and after the transition to growth

Changes in the topological state of DNA occur in a starvingEscherichia coli culture under oxidative stress caused by the addition of hydrogen peroxide. The addition of a carbon and energy source to this culture results in a second stress reaction. This supports previous data indicating that different mechanisms are responsible for the cell defense against oxidative stress in exponential and starvingE. coli cultures. Polyamine synthesis is involved in the cell adaptation to the stress. Putrescine binding to DNA and its dissociation seem to modulate the DNA topological state, which regulates the expression of the adaptive genes. An increase in the activity of the polyamine-synthesizing system in response to oxidative stress leads to a putrescine flux across the cytoplasmic membrane, due to which the antioxidant activity of putrescine protects the membrane phospholipids and contributes to the restoration of the cell energy-generating function     

JNK signaling in insulin-producing cells is required for adaptive responses to stress in Drosophila

Adaptation to environmental challenges is critical for the survival of an organism. Repression of Insulin/IGF Signaling (IIS) by stress-responsive Jun-N-terminal Kinase (JNK) signaling is emerging as a conserved mechanism that allows reallocating resources from anabolic to repair processes under stress conditions. JNK activation in Insulin-producing cells (IPCs) is sufficient to repress Insulin and Insulin-like peptide (ILP) expression in rats and flies, but the significance of this interaction for adaptive responses to stress is unclear. In this study, it is shown that JNK activity in IPCs of flies is required for oxidative stress-induced repression of the Drosophila ILP2. It is found that this repression is required for growth adaptation to heat stress as well as adult oxidative stress tolerance, and that induction of stress response genes in the periphery is in part dependent on IPC-specific JNK activity. Endocrine control of IIS by JNK in IPCs is thus critical for systemic adaptation to stress.     

Oxidative stress adaptation with acute,chronic, and repeated stress

Oxidative stress adaptation, or hormesis, is an important mechanism by which cells and organisms respond to, and cope with, environmental and physiological shifts in the level of oxidative stress. Most studies of oxidative stress adaption have been limited to adaptation induced by acute stress. In contrast, many if not most environmental and physiological stresses are either repeated or chronic. In this study we find that both cultured mammalian cells and the fruit fly Drosophila melanogaster are capable of adapting to chronic or repeated stress by upregulating protective systems, such as their proteasomal proteolytic capacity to remove oxidized proteins. Repeated stress adaptation resulted in significant extension of adaptive responses. Repeated stresses must occur at sufficiently long intervals, however (12-h or more for MEF cells and 7 days or more for flies), for adaptation to be successful, and the levels of both repeated and chronic stress must be lower than is optimal for adaptation to acute stress. Regrettably, regimens of adaptation to both repeated and chronic stress that were successful for short-term survival in Drosophila nevertheless also caused significant reductions in life span for the flies. Thus, although both repeated and chronic stress can be tolerated, they may result in a shorter life.     

植物应对干旱胁迫的阶段性策略

干旱是影响植物生存、生长和分布的最重要的非生物胁迫之一,全球暖干化将加剧干旱胁迫.植物对干旱胁迫的响应和适应机制一直是
学术研究的热点领域.本文综述了植物应对干旱胁迫的生长和生理响应,在已有的研究结果基础上,提出了植物应对干旱胁迫的阶段性响应策略.从干旱开始到干旱致死,植物经历了干旱开始-轻度干旱-中度干旱-严重干旱-极端干旱5个阶段,分别对应着应激响应-主动适应-被动适应3种响应方式和适应机制.不同阶段中植物抗旱机制的核心任务不同.最后提出了研究植物阶段性响应策略需要解决的关键科学问题及研究方向.     

Inheritance of osmotic adjustment to water stress in three grain sorghum crosses

Water stress is one of the major constraints to the grain yield of sorghum in tropical and sub-tropical areas of the world. Osmotic adjustment has been widely proposed as a plant attribute that confers adaptation to water stress. The inheritance of osmotic adjustment to water stress was investigated in a series of generations derived from the three possible bi-parental crosses between two inbred sorghum lines with a high capacity for osmotic adjustment (Tx2813 and TAM422; high-OA lines) and one with a low capacity (QL27; low-OA line). Broad-sense heritability on a single-plant basis was generally found to be high. Analysis of segregation ratios by the mixture method of clustering identified two independent major genes for high osmotic adjustment. The line Tx2813 possessed a recessive gene which is given the symbol oa1; the line TAM422 possessed an additive gene which is given the symbol OA2. There was some evidence that there may be other minor genes which influence the expression of osmotic adjustment in these crosses as two putative transgressive segregants, with higher osmotic adjustment than the parents, were identified from the cross between Tx2813 and TAM422. Populations of recombinant inbred lines were developed and characterised for osmotic adjustment for two of the crosses (QL27 x TAM422, low-OA x high-OA; Tx2813 x TAM422, high-oal x high-OA2). These will be used to conduct experiments which test hypotheses about the contribution of the high-osmotic-adjustment genes to the grain yield of sorghum under a range of water-stress conditions.