Understanding Of Stress Tolerance Mechanisms Research Articles

Molecular Marker Applications in the Selection of Elite Genotypes for Plant Stress Tolerance and Genetic Fidelity

Molecular markers play a crucial role in accelerating crop production for sustainable agriculture by identifying resistant traits and enhancing genetic diversity. In this review, we examine the impact of the molecular markers on advancing our understanding of stress tolerance mechanisms in plants, addressing the pressing imperative to bolster global food production to meet the escalating demands of the growing population. Additionally, the application of molecular markers to evaluate the genetic accuracy of plants due to genetic changes caused by somaclonal variation during <em>in vitro</em> propagation is mentioned. Specifically, we highlight emerging technologies like MAS, MARS, MABC, GWAS, GS, DH production, speed breeding, and genome editing, which offer promising opportunities to enhance stress tolerance and genetic integrity in crop cultivars, aiding in addressing global food security challenges. The literature search focused on studies published in the last ten years. We utilized a combination of specific and broad keywords such as genetic stability, <em>in vitro</em> propagation, molecular markers, abiotic-biotic stress, and plant biotechnology. In conclusion, this review analyzes the use of molecular markers in assessing the stress tolerance and genetic fidelity of <em>in vitro</em> grown plants.

Genome-Wide Characterization and Phylogenetic and Stress Response Expression Analysis of the MADS-Box Gene Family in Litchi (Litchi chinensis Sonn.).

The MADS-box protein is an important transcription factor in plants and plays an important role in regulating the plant abiotic stress response. In this study, a total of 94 MADS-box genes were predicted in the litchi genome, and these genes were widely distributed on all the chromosomes. The LcMADS-box gene family was divided into six subgroups (Mα, Mβ, Mγ, Mδ, MIKC, and UN) based on their phylogenetical relationships with Arabidopsis, and the closely linked subgroups exhibited more similarity in terms of motif distribution and intron/exon numbers. Transcriptome analysis indicated that LcMADS-box gene expression varied in different tissues, which can be divided into universal expression and specific expression. Furthermore, we further validated that LcMADS-box genes can exhibit different responses to various stresses using quantitative real-time PCR (qRT-PCR). Moreover, physicochemical properties, subcellular localization, collinearity, and cis-acting elements were also analyzed. The findings of this study provide valuable insights into the MADS-box gene family in litchi, specifically in relation to stress response. The identification of hormone-related and stress-responsive cis-acting elements in the MADS-box gene promoters suggests their involvement in stress signaling pathways. This study contributes to the understanding of stress tolerance mechanisms in litchi and highlights potential regulatory mechanisms underlying stress responses.

Introgression of SbERD4 Gene Encodes an Early-Responsive Dehydration-Stress Protein That Confers Tolerance against Different Types of Abiotic Stresses in Transgenic Tobacco.

Salicornia brachiata is an extreme halophyte that commonly grows on marsh conditions and is also considered a promising resource for drought and salt-responsive genes. To unveil a glimpse of stress endurance by plants, it is of the utmost importance to develop an understanding of stress tolerance mechanisms. ‘Early Responsive to Dehydration’ (ERD) genes are defined as a group of genes involved in stress tolerance and the development of plants. To increase this understanding, parallel to this expedited thought, a novel SbERD4 gene was cloned from S. brachiata, characterized, and functionally validated in the model plant tobacco. The study showed that SbERD4 is a plasma-membrane bound protein, and its overexpression in tobacco plants improved salinity and osmotic stress tolerance. Transgenic plants showed high relative water, chlorophylls, sugars, starch, polyphenols, proline, free amino acids, and low electrolyte leakage and H2O2 content compared to control plants (wild type and vector control) under different abiotic stress conditions. Furthermore, the transcript expression of antioxidant enzyme encoding genes NtCAT, NtSOD, NtGR, and NtAPX showed higher expression in transgenic compared to wild-type and vector controls under varying stress conditions. Overall, the overexpression of a novel early responsive to dehydration stress protein 4-encoding gene (SbERD4) enhanced the tolerance of the plant against multiple abiotic stresses. In conclusion, the overexpression of the SbERD4 gene mitigates plant physiology by enduring stress tolerance and might be considered as a promising key gene for engineering salinity and drought stress tolerance in crops.

Root traits of EuropeanVicia fabacultivars-Using machine learning to explore adaptations to agroclimatic conditions

Faba bean (Vicia faba L.) is an important source of protein, but breeding for increased yield stability and stress tolerance is hampered by the scarcity of phenotyping information. Because comparisons of cultivars adapted to different agroclimatic zones improve our understanding of stress tolerance mechanisms, the root architecture and morphology of 16 European faba bean cultivars were studied at maturity. Different machine learning (ML) approaches were tested in their usefulness to analyse trait variations between cultivars. A supervised, that is, hypothesis-driven, ML approach revealed that cultivars from Portugal feature greater and coarser but less frequent lateral roots at the top of the taproot, potentially enhancing water uptake from deeper soil horizons. Unsupervised clustering revealed that trait differences between northern and southern cultivars are not predominant but that two cultivar groups, independently from major and minor types, differ largely in overall root system size. Methodological guidelines on how to use powerful ML methods such as random forest models for enhancing the phenotypical exploration of plants are given.

Growth and biochemical analysis of evergreen haloxeric tree species Salvadora oleoides and Salvadora persica under NaCl stress

In vitro growth, development, total soluble proteins and peroxidase profiles of Salvadoraoleoides and Salvadora persica under NaCl stress were analysed in the present investigation. The plants are evergreen haloxeric tree species of family Salvadoraceae. Shoot apex from natural plants were initially used for screening of NaCl tolerance on MS culture medium. Shoot apex of S. oleoides and S. persica could survive optimally up to 200 and 100 mM NaCl. Axillary buds from nodal shoot segments of S. oleoides and S. persica were activated on 6 and 4 μM BAP, and were used further for extraction of total soluble proteins and peroxidases. Total soluble proteins were increased up to 150 mM NaCl in S. oleoides, but decline above 50 mM NaCl in S. persica. Peroxidase activity remained almost constant in S. oleoides at all the concentrations and duration of NaCl, but increased at 100 mM NaCl during fourth week of treatment in S. persica. Eleven peroxidase isozymes were observed in zymogram of S. oleoides. Isozymes P1, P2, P3, and P4 were slightly appeared, but P6 isozyme was lacking in S. persica. The P5 isozyme was more prominent in S. persica than S. oleoides. Isozyme P9 of S. persica was visible during the first week of NaCl treatment, but disappeared in the fourth week. Molecular biology of these plants can be useful further for the understanding of stress tolerance mechanisms for prospects.

Metabolic response of maize (Zea mays L.) plants to combined drought and salt stress

Maize is exposed to the combined stresses of water deficiency and soil salinity within its natural habitat, particularly in irrigated and dry land agricultural areas. Hence, the effect of these combined stresses on the metabolic response of maize plants was determined to improve understanding of stress tolerance mechanisms of maize in the field. Maize plants were either singly or simultaneously exposed to soil water deficiency and high salinity for 7 d. Physiological characteristics were analyzed and metabolic changes were quantified by conducting 1H NMR-based analysis of polar and non-polar fractions of maize leaf extracts. The response of maize plants to the combined stresses was distinct from that of plants subjected to either drought stress or salt stress alone at both the metabolic and physiological level. Maize plants showed a new pattern of metabolic response to the combined stresses. Some metabolites specifically responded to combined stresses and differed from those caused by each stress applied individually. The global metabolic response of maize to the combined stresses was related to the physiological processes. Our results provide valuable insights into the response of maize to combined drought and salt stress by linking stress-related physiological responses to changes in metabolites.

Current status and implications of engineering drought tolerance in plants using transgenic approaches.

Abstract Water deficit is a consequence of several different stresses including drought, salinity and extreme temperatures. It severely limits plant growth and productivity. Traditional plant breeding programmes have contributed significantly to the generation of stress-tolerant plants, but the process is rather time-consuming, expensive and hampered by the multigenic nature of the stress. Techniques developed in the field of plant molecular biology have the potential to modify plants for growth under unfavourable conditions and to provide new genotypes faster than traditional breeding is able to. The engineering of metabolic pathways associated with drought stress has emerged as a promising way to improve tolerance in model and crop plants. In recent years, efforts in this area have led to improvements in drought stress tolerance. Attempts to engineer improved drought tolerance using single- or multi-gene transfer of candidate genes offer rapid improvements in drought tolerance, although such genetic engineering strategies are limited by an incomplete understanding of stress tolerance mechanisms. Major efforts are required in molecular dissection of drought tolerance mechanisms in important crop plants. This review summarizes recent advances in elucidating stress response mechanisms and their biotechnological applications. Emphasis is placed on transgenic plants that exhibit improved drought tolerance. Various strategies to obtain drought-tolerant plants will be described and discussed.

Plant adaptation to acid, aluminum‐toxic soils

Abstract Aluminum (Al) toxicity is an important growth‐limiting factor for plants in many acid soils. The problem is not always economically correctable with conventional liming practices. But plant species and genotypes within species differ widely in tolerance to excess Al, and some of these differences are genetically controlled. Hence, an alternative or supplemental approach to the problem is to select or breed plant genotypes having greater tolerance to Al. A plant genetic approach has great potential for solving difficult soil fertility problems such as Al toxicity in acid subsoils. An important part of this approach is the determination of plant genetic, physiological and biochemical mechanisms by which plants tolerate mineral stress. Better understanding of stress tolerance mechanisms could lead to the development of more tolerant plants and more effective liming and fertilization practices for plants already in use. The objective of this presentation is to discuss our state of knowledge concerning the range of plant tolerance to excess Al, genetic control of tolerance and release of Al‐tolerant germplasm, and plant physiological and biochemical characteristics associated with differential Al tolerances among genotypes within species.