Rice Lesion Mimic Mutants (LMM): The Current Understanding of Genetic Mutations in the Failure of ROS Scavenging during Lesion Formation

Rice lesion mimic mutants (LMMs) form spontaneous lesions on the leaves during vegetative growth without pathogenic infections. The rice LMM group includes various mutants, including spotted leaf mutants, brown leaf mutants, white-stripe leaf mutants, and other lesion-phenotypic mutants. These LMM mutants exhibit a common phenotype of lesions on the leaves linked to chloroplast destruction caused by the eruption of reactive oxygen species (ROS) in the photosynthesis process. This process instigates the hypersensitive response (HR) and programmed cell death (PCD), resulting in lesion formation. The reasons for lesion formation have been studied extensively in terms of genetics and molecular biology to understand the pathogen and stress responses. In rice, the lesion phenotypes of most rice LMMs are inherited according to the Mendelian principles of inheritance, which remain in the subsequent generations. These rice LMM genetic traits have highly developed innate self-defense mechanisms. Thus, although rice LMM plants have undesirable agronomic traits, the genetic principles of LMM phenotypes can be used to obtain high grain yields by deciphering the efficiency of photosynthesis, disease resistance, and environmental stress responses. From these ailing rice LMM plants, rice geneticists have discovered novel proteins and physiological causes of ROS in photosynthesis and defense mechanisms. This review discusses recent studies on rice LMMs for the Mendelian inheritances, molecular genetic mapping, and the genetic definition of each mutant gene.

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Identification of a Novel Semi-Dominant Spotted-Leaf Mutant with Enhanced Resistance to Xanthomonas oryzae pv. oryzae in Rice

International Journal of Molecular Sciences ◽

10.3390/ijms19123766 ◽

2018 ◽

Vol 19 (12) ◽

pp. 3766 ◽

Cited By ~ 6

Author(s):

Zheng Chen ◽

Ting Chen ◽

Atul Sathe ◽

Yuqing He ◽

Xiao-bo Zhang ◽

...

Keyword(s):

Agronomic Traits ◽

Functional Characterization ◽

Nuclear Gene ◽

Xanthomonas Oryzae ◽

Sequencing Analysis ◽

Chromosome 11 ◽

Ros Scavenging ◽

Lesion Mimic ◽

Enhanced Resistance ◽

Leaf Mutant

Many spotted-leaf mutants show enhanced disease resistance to multiple pathogen attacks; however, the mechanisms are largely unknown. Here, we reported a novel semi-dominant spotted-leaf mutant 24 (spl24) obtained from an ethyl methane sulfonate (EMS)-induced IR64 mutant bank. spl24 developed tiny brown lesions on the leaf tip and spread down gradually to the leaf base as well as the sheath at the early heading stage. The performances of major agronomic traits such as the plant height, panicle length, number of panicles/plant, and 1000-grain weight were significantly altered in spl24 when compared to the wild-type IR64. Furthermore, spl24 exhibited a premature senescing phenotype with degeneration of nuclear acids, significantly reduced soluble protein content, increased level of malonaldehyde (MDA), and lowered activities of reactive oxygen species (ROS) scavenging enzymes. Disease evaluation indicated that spl24 showed enhanced resistance to multiple races of Xanthomonas oryzae pv. oryzae, the causal pathogen of bacterial leaf blight in rice, with elevated expression of pathogenesis-related genes, salicylic acid (SA) signaling pathway-associated genes revealed by real-time quantitative PCR and high-throughput RNA sequencing analysis. Genetic analysis and gene mapping indicated that the lesion mimic phenotype was controlled by a novel semi-dominant nuclear gene. The mutation, tentatively termed as OsSPL24, was in a 110 kb region flanked by markers Indel-33 and Indel-12 in chromosome 11. Together, our data suggest that spl24 is a novel lesion mimic mutant with enhanced innate immunity and would facilitate the isolation and functional characterization of the target gene.

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Proteomics and Metabolomics Studies on the Biotic Stress Responses of Rice: an Update

Rice ◽

10.1186/s12284-021-00461-4 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Kieu Thi Xuan Vo ◽

Md Mizanor Rahman ◽

Md Mustafizur Rahman ◽

Kieu Thi Thuy Trinh ◽

Sun Tae Kim ◽

...

Keyword(s):

Stress Responses ◽

Biotic Stress ◽

Defense Mechanisms ◽

Defense Responses ◽

Global Changes ◽

Biotic Stresses ◽

Novel Proteins ◽

Stress Agent ◽

Global Food ◽

Shed Light

AbstractBiotic stresses represent a serious threat to rice production to meet global food demand and thus pose a major challenge for scientists, who need to understand the intricate defense mechanisms. Proteomics and metabolomics studies have found global changes in proteins and metabolites during defense responses of rice exposed to biotic stressors, and also reported the production of specific secondary metabolites (SMs) in some cultivars that may vary depending on the type of biotic stress and the time at which the stress is imposed. The most common changes were seen in photosynthesis which is modified differently by rice plants to conserve energy, disrupt food supply for biotic stress agent, and initiate defense mechanisms or by biotic stressors to facilitate invasion and acquire nutrients, depending on their feeding style. Studies also provide evidence for the correlation between reactive oxygen species (ROS) and photorespiration and photosynthesis which can broaden our understanding on the balance of ROS production and scavenging in rice-pathogen interaction. Variation in the generation of phytohormones is also a key response exploited by rice and pathogens for their own benefit. Proteomics and metabolomics studies in resistant and susceptible rice cultivars upon pathogen attack have helped to identify the proteins and metabolites related to specific defense mechanisms, where choosing of an appropriate method to identify characterized or novel proteins and metabolites is essential, considering the outcomes of host-pathogen interactions. Despites the limitation in identifying the whole repertoire of responsive metabolites, some studies have shed light on functions of resistant-specific SMs. Lastly, we illustrate the potent metabolites responsible for resistance to different biotic stressors to provide valuable targets for further investigation and application.

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ROS Defense Systems and Terminal Oxidases in Bacteria

Antioxidants ◽

10.3390/antiox10060839 ◽

2021 ◽

Vol 10 (6) ◽

pp. 839

Author(s):

Vitaliy B. Borisov ◽

Sergey A. Siletsky ◽

Martina R. Nastasi ◽

Elena Forte

Keyword(s):

Defense Mechanisms ◽

Protective Role ◽

Superoxide Dismutases ◽

Oxygen Species ◽

Ros Scavenging ◽

Terminal Oxidases ◽

Defense Systems ◽

Respiratory Chains ◽

Scavenging Enzymes

Reactive oxygen species (ROS) comprise the superoxide anion (O2·−), hydrogen peroxide (H2O2), hydroxyl radical (·OH), and singlet oxygen (1O2). ROS can damage a variety of macromolecules, including DNA, RNA, proteins, and lipids, and compromise cell viability. To prevent or reduce ROS-induced oxidative stress, bacteria utilize different ROS defense mechanisms, of which ROS scavenging enzymes, such as superoxide dismutases, catalases, and peroxidases, are the best characterized. Recently, evidence has been accumulating that some of the terminal oxidases in bacterial respiratory chains may also play a protective role against ROS. The present review covers this role of terminal oxidases in light of recent findings.

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Increasing Solvent Tolerance to Improve Microbial Production of Alcohols, Terpenoids and Aromatics

Microorganisms ◽

10.3390/microorganisms9020249 ◽

2021 ◽

Vol 9 (2) ◽

pp. 249

Author(s):

Thomas Schalck ◽

Bram Van den Bergh ◽

Jan Michiels

Keyword(s):

Stress Responses ◽

Small Rnas ◽

Defense Mechanisms ◽

Industrial Processes ◽

Solvent Tolerance ◽

Adaptive Responses ◽

Environment Friendly ◽

Pathway Optimization ◽

Polymer Precursors ◽

Product Accumulation

Fuels and polymer precursors are widely used in daily life and in many industrial processes. Although these compounds are mainly derived from petrol, bacteria and yeast can produce them in an environment-friendly way. However, these molecules exhibit toxic solvent properties and reduce cell viability of the microbial producer which inevitably impedes high product titers. Hence, studying how product accumulation affects microbes and understanding how microbial adaptive responses counteract these harmful defects helps to maximize yields. Here, we specifically focus on the mode of toxicity of industry-relevant alcohols, terpenoids and aromatics and the associated stress-response mechanisms, encountered in several relevant bacterial and yeast producers. In practice, integrating heterologous defense mechanisms, overexpressing native stress responses or triggering multiple protection pathways by modifying the transcription machinery or small RNAs (sRNAs) are suitable strategies to improve solvent tolerance. Therefore, tolerance engineering, in combination with metabolic pathway optimization, shows high potential in developing superior microbial producers.

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Spermine: Its Emerging Role in Regulating Drought Stress Responses in Plants

Cells ◽

10.3390/cells10020261 ◽

2021 ◽

Vol 10 (2) ◽

pp. 261

Author(s):

Md. Mahadi Hasan ◽

Milan Skalicky ◽

Mohammad Shah Jahan ◽

Md. Nazmul Hossain ◽

Zunaira Anwar ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Stress Responses ◽

Abiotic Stresses ◽

Defense Mechanisms ◽

Antioxidant Defense ◽

Severe Drought ◽

New Information ◽

Effects Of Drought

In recent years, research on spermine (Spm) has turned up a lot of new information about this essential polyamine, especially as it is able to counteract damage from abiotic stresses. Spm has been shown to protect plants from a variety of environmental insults, but whether it can prevent the adverse effects of drought has not yet been reported. Drought stress increases endogenous Spm in plants and exogenous application of Spm improves the plants’ ability to tolerate drought stress. Spm’s role in enhancing antioxidant defense mechanisms, glyoxalase systems, methylglyoxal (MG) detoxification, and creating tolerance for drought-induced oxidative stress is well documented in plants. However, the influences of enzyme activity and osmoregulation on Spm biosynthesis and metabolism are variable. Spm interacts with other molecules like nitric oxide (NO) and phytohormones such as abscisic acid, salicylic acid, brassinosteroids, and ethylene, to coordinate the reactions necessary for developing drought tolerance. This review focuses on the role of Spm in plants under severe drought stress. We have proposed models to explain how Spm interacts with existing defense mechanisms in plants to improve drought tolerance.

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Mitochondrial Hormesis in PancreaticβCells: Does Uncoupling Protein 2 Play a Role?

Oxidative Medicine and Cellular Longevity ◽

10.1155/2012/740849 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

Ning Li ◽

Suzana Stojanovski ◽

Pierre Maechler

Keyword(s):

Stress Responses ◽

Defense Mechanisms ◽

Defense Mechanism ◽

Cell Function ◽

Uncoupling Protein ◽

Glucose Sensing ◽

Mitochondrial Uncoupling ◽

Mitochondrial Uncoupling Protein ◽

Cellular Stresses ◽

Excessive Nutrients

In pancreaticβcells, mitochondrial metabolism translates glucose sensing into signals regulating insulin secretion. Chronic exposure ofβcells to excessive nutrients, namely, glucolipotoxicity, impairsβ-cell function. This is associated with elevated ROS production from overstimulated mitochondria. Mitochondria are not only the major source of cellular ROS, they are also the primary target of ROS attacks. The mitochondrial uncoupling protein UCP2, even though its uncoupling properties are debated, has been associated with protective functions against ROS toxicity. Hormesis, an adaptive response to cellular stresses, might contribute to the protection againstβ-cell death, possibly limiting the development of type 2 diabetes. Mitochondrial hormesis, or mitohormesis, is a defense mechanism observed in ROS-induced stress-responses by mitochondria. Inβcells, mitochondrial damages induced by sublethal exogenous H2O2can induce secondary repair and defense mechanisms. In this context, UCP2 is a marker of mitohormesis, being upregulated following stress conditions. When overexpressed in nonstressed naïve cells, UCP2 confers resistance to oxidative stress. Whether treatment with mitohormetic inducers is sufficient to restore or ameliorate secretory function ofβcells remains to be determined.

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A Novel WRKY Transcription Factor from Ipomoea trifida, ItfWRKY70, Confers Drought Tolerance in Sweet Potato

International Journal of Molecular Sciences ◽

10.3390/ijms23020686 ◽

2022 ◽

Vol 23 (2) ◽

pp. 686

Author(s):

Sifan Sun ◽

Xu Li ◽

Shaopei Gao ◽

Nan Nie ◽

Huan Zhang ◽

...

Keyword(s):

Drought Stress ◽

Transgenic Plants ◽

Drought Tolerance ◽

Sweet Potato ◽

Stress Responses ◽

Leaf Tissue ◽

Stomatal Aperture ◽

Ros Scavenging ◽

Ipomoea Trifida ◽

Positive Role

WRKY transcription factors are one of the important families in plants, and have important roles in plant growth, abiotic stress responses, and defense regulation. In this study, we isolated a WRKY gene, ItfWRKY70, from the wild relative of sweet potato Ipomoea trifida (H.B.K.) G. Don. This gene was highly expressed in leaf tissue and strongly induced by 20% PEG6000 and 100 μM abscisic acid (ABA). Subcellar localization analyses indicated that ItfWRKY70 was localized in the nucleus. Overexpression of ItfWRKY70 significantly increased drought tolerance in transgenic sweet potato plants. The content of ABA and proline, and the activity of SOD and POD were significantly increased, whereas the content of malondialdehyde (MDA) and H2O2 were decreased in transgenic plants under drought stress. Overexpression of ItfWRKY70 up-regulated the genes involved in ABA biosynthesis, stress-response, ROS-scavenging system, and stomatal aperture in transgenic plants under drought stress. Taken together, these results demonstrated that ItfWRKY70 plays a positive role in drought tolerance by accumulating the content of ABA, regulating stomatal aperture and activating the ROS scavenging system in sweet potato.

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Genome-Wide Identification of Brassinosteroid Signaling Downstream Genes in Nine Rosaceae Species and Analyses of Their Roles in Stem Growth and Stress Response in Apple

Frontiers in Genetics ◽

10.3389/fgene.2021.640271 ◽

2021 ◽

Vol 12 ◽

Author(s):

Liwei Zheng ◽

Yingli Yang ◽

Shengjie Ma ◽

Wenming Wang ◽

Jimeng Zhang ◽

...

Keyword(s):

Stress Responses ◽

Agronomic Traits ◽

Purifying Selection ◽

Short Shoot ◽

Gene Expansion ◽

Rosaceae Species ◽

Genome Wide ◽

Brassinosteroid Signaling ◽

Stress Signals ◽

External Signals

Brassinosteroid signaling downstream genes regulate many important agronomic traits in rice. However, information on such genes is limited in Arabidopsis and Rosaceae species. We identified these genes in Arabidopsis and nine Rosaceae species. They were, respectively, named based on chromosomal locations. Segmental duplication and whole-genome duplication under purifying selection, as determined by Ka/Ks analysis, likely contributed to Rosaceae gene expansion. Apple (Malus domestica), Arabidopsis, and rice genes were generally similar, while several Rosaceae genes differed from their rice homologs in various characteristics, such as gene length, subcellular localization, transmembrane topology, conserved domains, secondary structures, and responses to external signals. The brassinosteroid downstream genes in apple were, respectively, induced or repressed by five phytohormones. Furthermore, these apple downstream genes were differentially expressed in different apple grafting combinations (“Nagafu No. 2”/“Malling 9” and “Nagafu No. 2”/“Nagafu No. 2”) and long–short shoot varieties (“Yanfu No. 6” and “Nagafu No. 2”). Responses of the MdBZR genes to diverse stress signals were examined and candidate hub genes were identified. These findings indicated that several brassinosteroid signaling downstream genes in Rosaceae functionally differed from their rice homologs, and certain apple genes may play roles in plant height and stress responses. This study provided valuable information and presented enriched biological theories on brassinosteroid signaling downstream genes in apple. Identification of such genes serve to help expand apple breeding and growth. This study provides useful information for brassinosteroid signaling downstream genes.

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EVOLUTION OF DNA SEQUENCING METHODS AND PROSPECTS FOR THEIR USE IN FORENSIC DNA EXAMINATION

Young Scientist ◽

10.32839/2304-5809/2020-11-87-27 ◽

2020 ◽

Vol 11 (87) ◽

Author(s):

Zhanna Bazyliuk ◽

Keyword(s):

Dna Sequencing ◽

Molecular Genetic ◽

Genetic Research ◽

Snp Markers ◽

Degraded Dna ◽

Phenotypic Traits ◽

Nucleotide Polymorphisms ◽

Biological Origin ◽

Genetic Traits ◽

Str Loci

The study of the human genome makes it possible to use genetic information to identify individual traits, diagnosis of diseases and forecasting and prevention of their development, promotes a personal approach when choosing treatment methods; population research, ethnogenesis and evolutionary processes. Introduction of DNA sequencing methods in domestic genetic fingerprinting will contribute to a more informative establishment of human genetic traits. The main purpose of molecular genetic research is to establish the genetic features of missing people, their relatives, to conduct paternity, to identify traces of biological origin and their identification. This article talks about the gradual development of DNA sequencing technology, which is conventionally divided into three types. The first type includes sequencing using capillary electrophoresis and pyrosequencing. The second type is high-throughput pyrosequencing, semiconductor, cyclic ligase, and the use of fluorescently labeled precursors, based on the sequencing of millions of DNA fragments simultaneously. The third stage includes methods that do not require prior sample preparation. These are methods of nanoporous sequencing, sequencing of one molecule, one-molecular sequencing. Today, each of the sequencing methods is aimed at performing different tasks. A number of methods are promising in the field of molecular-genetic examination. In world jurisprudence, sequencing is implemented mainly with the help of devices - Illumina’s, MiSeq FGx, Ion Torrent PGM from ThermoFisher and Ion S5. Research in forensic expertise of single nucleotide polymorphisms (SNP), sequencing of STR-loci and mitochondrial DNA, STR-loci and SNP-markers of the Y chromosome, will provide a high level of information, determination of human phenotypic traits, the possibility of establishing genetic traits from significantly degraded DNA. This article deals with modern problems of identification of human genetic traits and the prospect of introduction of the newest methods of sequencing for their qualitative and complete establishment.

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Proteomic Analysis of Cold Stress Responses in Banana Leaves

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.140.3.214 ◽

2015 ◽

Vol 140 (3) ◽

pp. 214-222 ◽

Cited By ~ 9

Author(s):

Ren-jun Feng ◽

Li-li Zhang ◽

Jing-yi Wang ◽

Jin-mei Luo ◽

Ming Peng ◽

...

Keyword(s):

Protein Synthesis ◽

Energy Metabolism ◽

Cold Stress ◽

Stress Responses ◽

Southern China ◽

Epigenetic Modification ◽

Stress Conditions ◽

Ros Scavenging ◽

Two Dimensional Gel Electrophoresis ◽

Cold Temperatures

Cold stress is one of the most important environmental factors affecting crop growth and agricultural production. Induced changes of gene expression and metabolism are critical for plants responding and acclimating to cold stress. Banana (Musa sp.) is one of the most important food crops in the tropical and subtropical countries of the world. Banana, which originated from tropical regions, is sensitive to cold, which can result in serious losses in commercial banana production. To investigate the response of the banana to cold stress conditions, changes in protein expression were analyzed using a comparative proteomics approach. ‘Brazil’ banana (Musa acuminata AAA group) is a common banana cultivar in southern China. ‘Brazil’ banana plantlets were exposed to 5 °C for 24 hours and then total crude protein was extracted from treatment and control leaves by phenol extraction, separated with two-dimensional gel electrophoresis, and subsequently identified by mass spectrometry (MS). Out of the more than 400 protein spots reproducibly detected, only 41 protein spots exhibited a change in intensity by at least 2-fold, with 26 proteins increasing and 15 proteins decreasing expression. Of these, 28 differentially expressed proteins were identified by MS. The identified proteins, including well-known and novel cold-responsive proteins, are involved in several cellular processes, including antioxidation and antipathogen, photosynthesis, chaperones, protein synthesis, signal transduction, energy metabolism, and other cellular functions. Proteins related to antioxidation, pathogen resistance, molecular chaperones, and energy metabolism were up-regulated, and proteins related to ethylene synthesis, protein synthesis, and epigenetic modification were down-regulated in response to cold temperature treatment. The banana plantlets incubated at cold temperatures demonstrated major changes in increased reactive oxygen species (ROS) scavenging, defense against diseases, and energy supply. Increased antioxidation capability in banana was also discovered in plantain, which has greater cold tolerance than banana in response to cold stress conditions. Therefore, we hypothesized that an increased antioxidation ability could be a common characteristic of banana and plantain in response to cold stress conditions. These findings may provide a better understanding of the physiological processes of banana in response to cold stress conditions.

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