Abiotic Stress Tolerance in Cotton

Cotton (Gossypium hirsutum L.) is a vital fiber crop that is being cultivated under diverse climatic conditions across the globe. The demand for cotton and its by-products is increasing day by day due to more consumption of this fiber in the textile industry and the utilization of cotton seed as a source of edible oil. However, the average seed cotton yield in the world is below that of the potential yield of cultivars. The factors responsible for low yield includes shortage of approved seed, pest and disease attack, weed infestation, unwise use of nutrients, and the incidence of abiotic stresses (including drought, heat, and salinity). Among these, the abiotic stresses are a single major factor, which is responsible for reducing the yield now and will affect the productivity of cotton in future. In this scenario, it is necessary to adopt ways to improve the tolerance of cotton against abiotic stresses. The strategies for improving tolerance against abiotic stresses may include the wise use of macro- and micronutrients, the use of osmoprotectants, the use of arbuscular mycorrhizal fungi, and the plant-growth promoting rhizobacteria

Interaction between salicylic acid and polyamines and their possible roles in tomato hardening processes

Long-term pre-treatment of tomato plants with low concentration of salicylic acid can induce abiotic stress tolerance by activating enzymatic and non-enzymatic antioxidant defense system. Changes of antioxidant defense system and catabolism of polyamines in tomato (Solanum lycopersicum) plants were investigated. Our results suggest that by affecting the polyamine catabolism salicylic acid can contribute to plant abiotic stress tolerance

Insights into salt tolerance from the genome of Thellungiella salsuginea

Thellungiella salsuginea, a close relative of Arabidopsis, represents an extremophile model for abiotic stress tolerance studies. We present the draft sequence of the T. salsuginea genome, assembled based on ∼134-fold coverage to seven chromosomes with a coding capacity of at least 28,457 genes. This genome provides resources and evidence about the nature of defense mechanisms constituting the genetic basis underlying plant abiotic stress tolerance. Comparative genomics and experimental analyses identified genes related to cation transport, abscisic acid signaling, and wax production prominent in T. salsuginea as possible contributors to its success in stressful environments

UNRAVELING THE REGULATORY BASIS OF THE DESICCATION TOLERANCE TRAIT IN Selaginella lepidophylla

Desiccation tolerance was a crucial adaptation for plants during their transition to terrestrial environments. Some spike mosses, including S. lepidophylla, have evolved the remarkable ability to tolerate extreme desiccation, enabling survival in arid regions of the world. However, the regulatory basis of this trait remains unknown. This dissertation aims to unravel the genetic basis of desiccation tolerance in Selaginella lepidophylla and its potential for improving crop abiotic stress tolerance. To achieve this goal, three objectives were pursued. Objective 1 focused on determining the regulatory role of the SlbHLH transcription factor (TF) by overexpressing it in Arabidopsis thaliana to assess its impact on water-use efficiency, abiotic stress tolerance, growth, and development. Objective 2 aimed to develop a genetic transformation protocol for Selaginella species, enabling the study of regulatory genes in S. lepidophylla and other Selaginella species. Objective 3 involved identifying dehydration responsive genes from transcriptome of S. lepidophylla during dehydration, providing insights into the desiccation mechanism and potential candidate genes for improving drought tolerance in crops. Our findings as the first to functionally characterize a TF from the spike moss, S. lepidophylla, revealed that the SlbHLH TF plays a crucial regulatory role in plant growth, development, abiotic stress tolerance, and water-use efficiency. Moreover, the development of a transformation system for Selaginella moellendorffii enables the study of regulatory genes in desiccation-tolerant spike mosses, including S. lepidophylla, thereby enhancing our understanding of desiccation tolerance mechanisms. Furthermore, the identification of dehydration responsive genes associated with desiccation tolerance of S. lepidophylla provides valuable genomic resources for improving abiotic stress tolerance in crop plants. Altogether, this dissertation advances our understanding of the genetic basis of desiccation tolerance in S. lepidophylla and proposes practical approaches for enhancing crop abiotic stress tolerance. Furthermore, the development of a genetic transformation system for Selaginella and the transcriptomic analysis of S. lepidophylla provide essential tools and insights for studying desiccation tolerance mechanisms and regulatory networks, thus paving the way for future advancements in crop improvements and sustainable agriculture

Міжнародна конференція «Толерантність рослин до абіотичних стресів»

Міжнародна конференція «Толерантність рослин до абіотичних стресів» («Plant Abiotic Stress Tolerance») відбулася 8—11 лютого 2009 р. у столиці Австрії

Evaluating chickpea genotypes for abiotic stress tolerance

Being a leguminous crop chickpea (Cicer arietinum L.) is important for the establishment of sustainable and economically viable farming systems. Chickpea is grown and consumed across five continents, making this crop more important in international markets than other food legumes. Adaptation trials of 15 accessions of chickpea, 13 from the ICARDA collection and 2 from the Portuguese national catalogue, took place during two years in two different countries (Portugal, Syria). The trials were conducted under rainfed conditions using a late sowing date to naturally expose the plants to drought and heat stress. The accumulated results indicate a high variability in the yield response among genotypes and regions. In Portugal differences between the most productive accession and the least productive one was higher than 1000 kg/ha in 2009 (drought year) and than 1500Kg/ha in 2010 (rainy year). In general, genotypes that fasten their development cycle showed higher grain yield, especially in drought years. Comparing the two years, we observed three groups of genotypes: i) Stable genotypes, well adapted to distinct environments (like ILC588). ii) Genotypes adapted to adverse conditions, but not responding to favourable conditions (ICL 216); this genotype was also among the best performers under drought conditions in Syria. iii) Genotypes adapted to good conditions, but with bad performance under adverse conditions (ICL 3279). Across the two locations, Portugal and Syria, FLIP03-145C, FLIP87-8C and ILC 588 were on the top 5 during 2009. In 2010, only FLIP87-8C standout to be among the best performers under drought conditions in both countries

Abscisic Acid Signalling as a Target for Enhancing Drought Tolerance

Abscisic acid (ABA) is a vital hormone that confers abiotic stress tolerance in plants. The identification of PYR/PYL/RCAR proteins as bona fide ABA receptors and the subsequent elucidation of the structural mechanisms of the core ABA signalling pathway in recent years has provided new and powerful insights in targeting ABA signalling to enhance abiotic stress tolerance in agriculture. This chapter reviews the components and molecular mechanisms of the core ABA signalling pathway, as revealed by X-ray crystallography studies, and how these knowledge led to preliminary efforts in novel biotechnological developments to improve stress tolerance in plants

Oil palm EgCBF3 conferred stress tolerance in transgenic tomato plants through modulation of the ethylene signaling pathway

CBF/DREB1 is a group of transcription factors that are mainly involved in abiotic stress tolerance in plants. They belong to the AP2/ERF superfamily of plant-specific transcription factors. A gene encoding a new member of this group was isolated from ripening oil palm fruit and designated as EgCBF3. The oil palm fruit demonstrates the characteristics of a climacteric fruit like tomato, in which ethylene has a major impact on the ripening process. A transgenic approach was used for functional characterization of the EgCBF3, using tomato as the model plant. The effects of ectopic expression of EgCBF3 were analyzed based on expression profiling of the ethylene biosynthesis-related genes, anti-freeze proteins (AFPs), abiotic stress tolerance and plant growth and development. The EgCBF3 tomatoes demonstrated altered phenotypes compared to the wild type tomatoes. Delayed leaf senescence and flowering, increased chlorophyll content and abnormal flowering were the consequences of overexpression of EgCBF3 in the transgenic tomatoes. The EgCBF3 tomatoes demonstrated enhanced abiotic stress tolerance under in vitro conditions. Further, transcript levels of ethylene biosynthesis-related genes, including three SlACSs and two SlACOs, were altered in the transgenic plants’ leaves and roots compared to that in the wild type tomato plant. Among the eight AFPs studied in the wounded leaves of the EgCBF3 tomato plants, transcript levels of SlOSM-L, SlNP24, SlPR5L and SlTSRF1 decreased, while expression of the other four, SlCHI3, SlPR1, SlPR-P2 and SlLAP2, were up-regulated. These findings indicate the possible functions of EgCBF3 in plant growth and development as a regulator of ethylene biosynthesis-related and AFP genes, and as a stimulator of abiotic stress tolerance

Citric Acid-Mediated Abiotic Stress Tolerance in Plants

Several recent studies have shown that citric acid/citrate (CA) can confer abiotic stress tolerance to plants. Exogenous CA application leads to improved growth and yield in crop plants under various abiotic stress conditions. Improved physiological outcomes are associated with higher photosynthetic rates, reduced reactive oxygen species, and better osmoregulation. Application of CA also induces antioxidant defense systems, promotes increased chlorophyll content, and affects secondary metabolism to limit plant growth restrictions under stress. In particular, CA has a major impact on relieving heavy metal stress by promoting precipitation, chelation, and sequestration of metal ions. This review summarizes the mechanisms that mediate CA-regulated changes in plants, primarily CA's involvement in the control of physiological and molecular processes in plants under abiotic stress conditions. We also review genetic engineering strategies for CA-mediated abiotic stress tolerance. Finally, we propose a model to explain how CA's position in complex metabolic networks involving the biosynthesis of phytohormones, amino acids, signaling molecules, and other secondary metabolites could explain some of its abiotic stress-ameliorating properties. This review summarizes our current understanding of CA-mediated abiotic stress tolerance and highlights areas where additional research is needed