Multiple Abiotic Stress Tolerance Research Articles

Enhancing stress resilience in rice (Oryza sativa L.) through profiling early-stage morpho-physiological and molecular responses to multiple abiotic stress tolerance.

Under changing climatic conditions, crop plants are more adversely affected by a combination of various abiotic stresses than by a single abiotic stress. Therefore, it is essential to identify potential donors to multiple abiotic stresses for developing climate-resilient crop varieties. Hence, the present study was undertaken with 41 germplasm accessions comprising native landraces of Tamil Nadu, Prerelease lines and cultivars were screened independently for drought, salinity, and submergence at the seedling stage during Kharif and Rabi 2022-2023. Stress was imposed separately for these three abiotic stresses on 21-day-old seedlings and was maintained for 10 days. The studied genotypes showed a significant reduction in plant biomass (PB), Relative Growth Index (RGI), relative water content (RWC), leaf photosynthesis, chlorophyll fluorescence, and Chlorophyll Concentration Index (CCI) under drought followed by salinity and submergence. Stress-tolerant indices for drought, salinity, and submergence revealed significant variation for plant biomass. Furthermore, a set of 30 SSR markers linked to drought, salinity, and submergence QTLs has been used to characterize 41 rice germplasm accessions. Our analysis suggests a significantly high polymorphism, with 28 polymorphic markers having a 93.40% in 76 loci. The mean values of polymorphic information content (PIC), heterozygosity index (HI), marker index (MI), and resolving power (RP) were 0.369, 0.433, 1.140, and 2.877, respectively. Jaccard clustering grouped all the genotypes into two major and six subclusters. According to STRUCTURE analysis, all genotypes were grouped into two major clusters, which are concurrent with a very broad genetic base (K = 2). Statistically significant marker-trait associations for biomass were observed for five polymorphic markers, viz., RM211, RM212 (drought), RM10694 (salinity), RM219, and RM21 (submergence). Similarly, significant markers for relative shoot length were observed for RM551 (drought), RM10694 (salinity), and ART5 (submergence). Notably, the genotypes Mattaikar, Varigarudan samba, Arupatham samba, and APD19002 were identified as potential donors for multiple abiotic stress tolerance. Thus, identifying the genetic potential of germplasm could be useful for enhancing stress resilience in rice.

Evaluation for Multiple Abiotic Stress Tolerance in Rice (Oryza Sativa) Genotypes

Evaluation for Multiple Abiotic Stress Tolerance in Rice (Oryza Sativa) Genotypes

Pyramiding of transcription factor, PgHSF4, and stress-responsive genes of p68, Pg47, and PsAKR1 impart multiple abiotic stress tolerance in rice (Oryza sativa L.).

Abiotic stresses such as drought, salinity, and heat stress significantly affect rice crop growth and production. Under uncertain climatic conditions, the concurrent multiple abiotic stresses at different stages of rice production became a major challenge for agriculture. Hence, improving rice's multiple abiotic stress tolerance is essential to overcome unprecedented challenges under adverse environmental conditions. A significant challenge for rice breeding programs in improving abiotic stress tolerance involves multiple traits and their complexity. Multiple traits must be targeted to improve multiple stress tolerance in rice and uncover the mechanisms. With this hypothesis, in the present study gene stacking approach is used to integrate multiple traits involved in stress tolerance. The multigene transgenics co-expressing Pennisetum glaucum 47 (Pg47), Pea 68 (p68), Pennisetum glaucum Heat Shock Factor 4(PgHSF4), and Pseudomonas Aldo Keto Reductase 1 (PsAKR1) genes in the rice genotype (AC39020) were developed using the in-planta transformation method. The promising transgenic lines maintained higher yields under semi-irrigated aerobic cultivation (moisture stress). These 15 promising transgenic rice seedlings showed improved shoot and root growth traits under salinity, accelerating aging, temperature, and oxidative stress. They showed better physiological characteristics, such as chlorophyll content, membrane stability, and lower accumulation of reactive oxygen species, under multiple abiotic stresses than wild-type. Enhanced expression of transgenes and other stress-responsive downstream genes such as HSP70, SOD, APX, SOS, PP2C, and P5CS in transgenic lines suggest the possible molecular mechanism for imparting the abiotic stress tolerance. This study proved that multiple genes stacking as a novel strategy induce several mechanisms and responsible traits to overcome multiple abiotic stresses. This multigene combination can potentially improve tolerance to multiple abiotic stress conditions and pave the way for developing climate-resilient crops.

GASA Proteins: Review of Their Functions in Plant Environmental Stress Tolerance.

Gibberellic acid-stimulated Arabidopsis (GASA) gene family is a class of functional cysteine-rich proteins characterized by an N-terminal signal peptide and a C-terminal-conserved GASA domain with 12 invariant cysteine (Cys) residues. GASA proteins are widely distributed among plant species, and the majority of them are involved in the signal transmission of plant hormones, the regulation of plant development and growth, and the responses to different environmental constraints. To date, their action mechanisms are not completely elucidated. This review reports an overview of the diversity, structure, and subcellular localization of GASA proteins, their involvement in hormone crosstalk and redox regulation during development, and plant responses to abiotic and biotic stresses. Knowledge of this complex regulation can be a contribution to promoting multiple abiotic stress tolerance with potential agricultural applications through the engineering of genes encoding GASA proteins and the production of transgenic plants.

Screening and identification of multiple abiotic stress responsive candidate genes based on hybrid-sequencing in Vicia sativa

Common vetch is an important leguminous forage for both livestock fodder and green manure and has a tremendous latent capacity in a sustainable agroecosystem. In the present study, a comprehensive transcriptome analysis of the aboveground leaves and underground roots of common vetch under multiple abiotic stress treatments, including NaCl, drought, cold, and cold drought, was performed using hybrid-sequencing technology, i. e. single-molecule real-time sequencing technology (SMRT) and supplemented by next-generation sequencing (NGS) technology. A total of 485,038 reads of insert (ROIs) with a mean length of 2606 bp and 228,261 full-length nonchimeric (FLNC) reads were generated. After deduplication, 39,709 transcripts were generated. Of these transcripts, we identified 1059 alternative splicing (AS) events, 17,227 simple sequence repeats (SSRs), and 1647 putative transcription factors (TFs). Furthermore, 640 candidates long noncoding RNAs (lncRNAs) and 28,256 complete coding sequences (CDSs) were identified. In gene annotation analyses, a total of 38,826 transcripts (97.78%) were annotated in eight public databases. Finally, seven multiple abiotic stress-responsive candidate genes were obtained through gene expression, annotation information, and protein-protein interaction (PPI) networks. Our research not only enriched the structural information of FL transcripts in common vetch, but also provided useful information for exploring the molecular mechanism of multiple abiotic stress tolerance between aboveground and underground tissues in common vetch and related legumes.

Genotypic diversity and abiotic stress response profiling of short-grain aromatic landraces of rice (Oryza sativa L. Indica)

This study evaluated the physiological responses and genetic diversity of selected short-grain aromatic rice landraces of Northern Eastern Ghats of India to multiple abiotic stresses. Results revealed that drought, salt and flooding stress remarkably declined plant biomass, relative growth index (RGI), relative water content (RWC), leaf photosynthesis, PSII activity, SPAD relative index, and elevated effect was found in susceptible IR64 (susceptible check) variety. We employed molecular marker analysis to characterize 21 rice genotypes using 32 SSR primers related to drought, flooding and salinity tolerance QTLs. Our analysis suggests significantly high polymorphism (93.12%) in 96 loci. The mean value of polymorphism information content (PIC), marker index (MI) and resolving power (RP) and heterozygosity index (HI) were 0.326, 1.037, 1.558 and 0.420 respectively. The Jaccard’s similarity coefficient ranged from 0.158 to 0.846 with a mean genetic dissimilarity of 0.647. According to neighbor-joining method of clustering, all genotypes were grouped into two major and five sub-clusters which is concurrent with a very broad genetic base (K = 5) obtained with STRUCTURE analysis. Taken together, six aromatic genotypes Basubhoga, Dudhamani, Kalajeera, Laktimachi, Kuyerkuling and Tulasi are genetically very close to drought-tolerant (N22) and flooding tolerant (FR13A) cultivar whereas, salt-tolerant (Pokkali) very close to Sapuri and Muktabali. The degree of genetic variants obtained from this profiling could be useful for landrace conservation, selection and global implications for multiple abiotic stress tolerance.

A systematical genome-wide analysis and screening of WRKY transcription factor family engaged in abiotic stress response in sweetpotato

BackgroundWRKY transcription factors play pivotal roles in regulating plant multiple abiotic stress tolerance, however, a genome-wide systematical analysis of WRKY genes in sweetpotato is still missing.ResultsHerein, 84 putative IbWRKYs with WRKY element sequence variants were identified in sweetpotato reference genomes. Fragment duplications, rather than tandem duplications, were shown to play prominent roles in IbWRKY gene expansion. The collinearity analysis between IbWRKYs and the related orthologs from other plants further depicted evolutionary insights into IbWRKYs. Phylogenetic relationships displayed that IbWRKYs were divided into three main groups (I, II and III), with the support of the characteristics of exon-intron structures and conserved protein motifs. The IbWRKY genes, mainly from the group Ib, displayed remarkable and diverse expression profiles under multiple abiotic stress (NaCl, PEG6000, cold and heat) and hormone (ABA, ACC, JA and SA) treatments, which were determined by RNA-seq and qRT-PCR assays, suggesting their potential roles in mediating particular stress responses. Moreover, IbWRKY58L could interact with IbWRKY82 as revealed by yeast two-hybrid based on the protein interaction network screening. And abiotic stress-remarkably induced IbWRKY21L and IbWRKY51 were shown to be localized in the nucleus and had no transactivation activities.ConclusionThese results provide valuable insights into sweetpotato IbWRKYs and will lay a foundation for further exploring functions and possible regulatory mechanisms of IbWRKYs in abiotic stress tolerance.

ThASR3 confers salt and osmotic stress tolerances in transgenic Tamarix and Arabidopsis

BackgroundASR (abscisic acid-, stress-, and ripening-induced) gene family plays a crucial role in responding to abiotic stresses in plants. However, the roles of ASR genes protecting plants against high salt and drought stresses remain unknown in Tamarix hispida.ResultsIn this study, a salt and drought-induced ASR gene, ThASR3, was isolated from Tamarix hispida. Transgenic Arabidopsis overexpressing ThASR3 exhibited stimulating root growth and increasing fresh weight compared with wild-type (WT) plants under both salt and water deficit stresses. To further analyze the gain- and loss-of-function of ThASR3, the transgenic T. hispida plants overexpressing or RNA interference (RNAi)-silencing ThASR3 were generated using transient transformation. The overexpression of ThASR3 in Tamarix and Arabidopsis plants displayed enhanced reactive oxygen species (ROS) scavenging capability under high salt and osmotic stress conditions, including increasing the activities of antioxidant enzymes and the contents of proline and betaine, and reducing malondialdehyde (MDA) content and electrolyte leakage rates.ConclusionOur results indicate that ThASR3 functions as a positive regulator in Tamarix responses to salt and osmotic stresses and confers multiple abiotic stress tolerances in transgenic plants, which may have an important application value in the genetic improvement of forest tree resistance.

A Study of Scion Phenotypes in Pummelo Grafted onto a New Citrus Rootstock Citrus junos ‘Pujiang Xiangcheng’

Citrus is one of the most important fruit crops in the world. Citrus junos Siebold ex Tanaka cv. Pujiang Xiangcheng is a new rootstock with a good grafting affinity and multiple abiotic stress tolerance. In this study, the effects of ‘Pujiang Xiangcheng’ and two commonly used rootstocks for Citrus maxima (Burm.) Merrill cv. Guanxi Miyou, considering their growth, photosynthetic performance, phytohormones and fruit quality, were evaluated. There was little difference between three graft combinations in the height and diameter of the scions. However, the rootstock ‘Pujiang Xiangcheng’ can cause an up-regulated photosynthetic capacity. In addition, ‘Guanxi Miyou’ on ‘Pujiang Xiangcheng’ had the highest total sugar (TS) content (129.28 mg·g−1) and the lowest titratable acid (TA) content (0.78 g·100 mL−1) in 2020 and the highest TSS (11.84%) in 2021. There was no significant difference in the TSS-to-acid ratio between the fruit of ‘Guanxi Miyou’ on trifoliate orange (13.41) and ‘Pujiang Xiangcheng’ (15.68), but it was significantly higher than that of ‘Guanxi Miyou’ on sour pummelo (11.61). Moreover, the comprehensive fruit quality of ‘Guanxi Miyou’ on ‘Pujiang Xiangcheng’ was better than on sour pummelo and trifoliate orange based on two-year statistics. We suggest that ‘Pujiang Xiangcheng’ might be the appropriate rootstock of ‘Guanxi Miyou’ in production compared with sour pummelo and trifoliate orange.

Cowpea NAC1/NAC2 transcription factors improve growth and tolerance to drought and heat in transgenic cowpea through combined activation of photosynthetic and antioxidant mechanisms.

NAC (NAM/ATAF1/2/CUC2) transcription factors are central switches of growth and stress responses in plants. However, unpredictable interspecies conservation of function and regulatory targets makes the well-studied NAC orthologs inapt for pulse engineering. The knowledge of suitable NAC candidates in hardy pulses like cowpea (Vigna unguiculata (L.) Walp.) is still in infancy, hence warrants immediate biotechnological intervention. Here, we showed that overexpression of two native NAC genes (VuNAC1 and VuNAC2) promoted germinative, vegetative, and reproductive growth and conferred multiple abiotic stress tolerance in a commercial cowpea variety. The transgenic lines displayed increased leaf area, thicker stem, nodule-rich denser root system, early flowering, higher pod production (∼3.2-fold and ∼2.1-fold), and greater seed weight (10.3% and 6.0%). In contrast, transient suppression of VuNAC1/2 caused severe growth retardation and flower inhibition. The overexpressor lines showed remarkable tolerance to major yield-declining terminal stresses, such as drought, salinity, heat, and cold, and recovered growth and seed production by boosting photosynthetic activity, water use efficiency, membrane integrity, Na+ /K+ homeostasis, and antioxidant activity. The comparative transcriptome study indicated consolidated activation of genes involved in chloroplast development, photosynthetic complexes, cell division and expansion, cell wall biogenesis, nutrient uptake and metabolism, stress response, abscisic acid, and auxin signaling. Unlike their orthologs, VuNAC1/2 direct synergistic transcriptional tuning of stress and developmental signaling to avoid unwanted trade-offs. Their overexpression governs the favorable interplay of photosynthesis and reactive oxygen species regulation to improve stress recovery, nutritional sufficiency, biomass, and production. This unconventional balance of strong stress tolerance and agronomic quality is useful for translational crop research and molecular breeding of pulses.

Consensus genomic regions associated with multiple abiotic stress tolerance in wheat and implications for wheat breeding

In wheat, a meta-analysis was performed using previously identified QTLs associated with drought stress (DS), heat stress (HS), salinity stress (SS), water-logging stress (WS), pre-harvest sprouting (PHS), and aluminium stress (AS) which predicted a total of 134 meta-QTLs (MQTLs) that involved at least 28 consistent and stable MQTLs conferring tolerance to five or all six abiotic stresses under study. Seventy-six MQTLs out of the 132 physically anchored MQTLs were also verified with genome-wide association studies. Around 43% of MQTLs had genetic and physical confidence intervals of less than 1 cM and 5 Mb, respectively. Consequently, 539 genes were identified in some selected MQTLs providing tolerance to 5 or all 6 abiotic stresses. Comparative analysis of genes underlying MQTLs with four RNA-seq based transcriptomic datasets unravelled a total of 189 differentially expressed genes which also included at least 11 most promising candidate genes common among different datasets. The promoter analysis showed that the promoters of these genes include many stress responsiveness cis-regulatory elements, such as ARE, MBS, TC-rich repeats, As-1 element, STRE, LTR, WRE3, and WUN-motif among others. Further, some MQTLs also overlapped with as many as 34 known abiotic stress tolerance genes. In addition, numerous ortho-MQTLs among the wheat, maize, and rice genomes were discovered. These findings could help with fine mapping and gene cloning, as well as marker-assisted breeding for multiple abiotic stress tolerances in wheat.

Comparative RNA sequencing for deciphering nodes of multiple abiotic stress tolerance in lentil (Lens culinaris Medikus)

Lentil is a highly proteinaceous crop whose productivity is severely hampered by various abiotic stresses. Transcriptome analysis unveils important metabolic pathways, regulatory genes and can help in identification of genomic resources which can be utilized for ameliorating abiotic stress tolerance. Therefore, the present study was undertaken to dissect transcriptomes of contrasting lentil genotypes under different stresses; drought, heat, salinity and alkalinity. Differential gene expression analysis and annotation were conducted by de novo transcriptomics and their functional correlation under diverse stresses was established using gene ontology analyses. Major differentially expressed genes (DEGs) which were found to be up-regulated under drought and heat stresses were involved in organic acid synthesis and translational regulation. Similarly, DEGs which were co-upregulated under salinity and alkalinity stresses belonged to abscisic acid (ABA) signaling, epigenetic regulation, sucrose transport, vesicular trafficking and regulation of cation transport at the root symplast-xylem interface. Data generated in this study can be used to elucidate converging tolerance pathways under multiple abiotic stresses. The information can be utilized in molecular breeding and gene pyramiding programmes of lentil and related species.

Plant growth-promoting actinobacterial inoculant assisted phytoremediation increases cadmium uptake in Sorghum bicolor under drought and heat stresses

In this study, two proficient Cadmium (Cd) resistant and plant growth-promoting actinobacterial strains were isolated from metal-polluted soils and identified as Streptomyces sp. strain RA04 and Nocardiopsis sp. strain RA07. Multiple abiotic stress tolerances were found in these two actinobacterial strains, including Cd stress (CdS), drought stress (DS) and high-temperature stress (HTS). Both actinobacterial strains exhibited multifarious plant growth-promoting (PGP) traits such as phosphate solubilization, and production of indole-3-acetic acid, siderophores and 1-aminocyclopropane-1-carboxylate deaminase under CdS, DS and HTS conditions. The inoculation of strains RA04 and RA07 significantly increased Sorghum bicolor growth and photosynthetic pigments under CdS, DS, HTS, CdS + DS and CdS + HTS conditions as compared to their respective uninoculated plants. The actinobacterial inoculants reduced malondialdehyde concentration and enhanced antioxidant enzymes in plants cultivated under various abiotic stress conditions, indicating that actinobacterial inoculants reduced oxidative damage. Furthermore, strains RA04 and RA07 enhanced the accumulation of Cd in plant tissues and the translocation of Cd from root to shoot under CdS, CdS + DS and CdS + HTS treatments as compared to their respective uninoculated plants. These findings suggest that RA04 and RA07 strains could be effective bio-inoculants to accelerate phytoremediation of Cd polluted soil even in DS and HTS conditions.

Identification of major candidate genes for multiple abiotic stress tolerance at seedling stage by network analysis and their validation by expression profiling in rice (Oryza sativa L.).

The online version contains supplementary material available at 10.1007/s13205-022-03182-7.

A novel thaumatin-like protein from durum wheat, TdPR-5, is homologous to known plant allergens, responsive to stress exposure, and confers multiple-abiotic stress tolerances to transgenic yeast

Thaumatin-like proteins (TLPs) are highly complex group of Pathogenesis-Related proteins (PRs) recognized as human allergens. They are known to rapidly accumulate in high levels following stresses. Several members of TLPs were isolated from different plant species, but few were described in durum wheat. In this study, a PR-5 member, TdPR-5, was isolated from a Tunisian variety of durum wheat. Phylogenetic analysis showed that TdPR-5 protein shared high homology with TLPs isolated from several plant species. Allergenic assessment of TdPR-5, using Allermatch tool, revealed that TdPR-5 had significant identity with TLPs, known as plant allergens. qRT-PCR analysis revealed that TdPR-5 is robustly induced by drought, salt and heavy metals such as cadmium (Cd), copper (Cu) and zinc (Zn). Notably, TdPR-5 induction is concomitant with the induction of the durum wheat transcription factor TdSHN1 shown previously to control the expression of tobacco PR-5 gene when overexpressed in transgenic tobacco plants. Maximum fold-change in relative expression of TdPR-5 and TdSHN1 genes following stress treatments reached 6.5 times (mannitol 1 h) and 10 times (Cu 24 h), respectively. Heterologous expression of TdPR-5 in transgenic yeast conferred resistance to multiple abiotic stresses. These results indicated that TdPR-5 may play an important role in multiple abiotic stress tolerance in wheat. This study also provides valuable information regarding food safety. In fact, overexpression of strong transcription factors such as TdSHN1 or exposure of plants to stressful conditions can lead to an increase in the quantity of allergens in crops thereby increasing the risk for consumers with known allergy or sensitization.

Rice CIRCADIAN CLOCK ASSOCIATED 1 transcriptionally regulates ABA signaling to confer multiple abiotic stress tolerance.

The circadian clock facilitates the survival and reproduction of crop plants under harsh environmental conditions such as drought and osmotic and salinity stresses, mainly by reprogramming the endogenous transcriptional landscape. Nevertheless, the genome-wide roles of core clock components in rice (Oryza sativa L.) abiotic stress tolerance are largely uncharacterized. Here, we report that CIRCADIAN CLOCK ASSOCIATED1 (OsCCA1), a vital clock component in rice, is required for tolerance to salinity, osmotic, and drought stresses. DNA affinity purification sequencing coupled with transcriptome analysis identified 692 direct transcriptional target genes of OsCCA1. Among them, the genes involved in abscisic acid (ABA) signaling, including group A protein phosphatase 2C genes and basic region and leucine zipper 46 (OsbZIP46), were substantially enriched. Moreover, OsCCA1 could directly bind the promoters of OsPP108 and OsbZIP46 to activate their expression. Consistently, oscca1 null mutants generated via genome editing displayed enhanced sensitivities to ABA signaling. Together, our findings illustrate that OsCCA1 confers multiple abiotic stress tolerance likely by orchestrating ABA signaling, which links the circadian clock with ABA signaling in rice.

Molecular characterization and varietal identification for multiple abiotic stress tolerance in rice (Oryza sativa L.)

Coexistence of two or more abiotic stresses is common in most of the rainfed lowland and upland rice growing areas of India and worldwide. Rice production under these conditions is not sustainable. Identification and development of multiple abiotic stress tolerant rice varieties are to be addressed. Here we tried to identify multiple abiotic stress tolerant varieties from a collection of earlier identified varieties for single stress and validated the known SSR markers for stress tolerance. Twenty rice genotypes were evaluated for individual abiotic stress such as drought, salinity and temperature initially and the tolerant three genotypes in each case were further evaluated for combination of stresses various physio-morphological and biochemical parameters were recorded. Among the genotypes evaluated for combination of stresses, PTB-7 was found to be tolerant for drought and salinity, Nagina-22 was tolerant against high temperature and salinity. However, the seeds did not germinate in the presence of all three stresses simultaneously. Twenty rice varieties viz., Chomala, MO-16, PTB-35, PTB-60, PTB-39, PTB-55, PTB-30, PTB-7, CRdhan307, Apo, Vyttila-3, Vyttila-4, Vyttila-5, Vyttila-6, Vyttila-7, Vyttila-8, Vyttila-9, Vyttila-10, Nagina-22 and NL-44 were further investigated using microsatellite markers to confirm the genotypic level of tolerance to combination of abiotic stresses. Rice genotypes were screened using 30 reported simple sequence repeat (SSR) markers that are linked to drought, salinity and temperature. Molecular marker analysis of rice genotypes also confirmed that RM8904 and RM1287 were associated with salinity tolerance, RM2612, RM6100 and RM5749 were linked to high temperature tolerant trait. Population analysis also revealed that there is five subpopulation among rice genotypes.

Hydrogen sulfide: an emerging component against abiotic stress in plants.

As a result of climate change, abiotic stresses are the most common cause of crop losses worldwide. Abiotic stresses significantly impair plants' physiological, biochemical, molecular and cellular mechanisms, limiting crop productivity under adverse climate conditions. However, plants can implement essential mechanisms against abiotic stressors to maintain their growth and persistence under such stressful environments. In nature, plants have developed several adaptations and defence mechanisms to mitigate abiotic stress. Moreover, recent research has revealed that signalling molecules like hydrogen sulfide (H2 S) play a crucial role in mitigating the adverse effects of environmental stresses in plants by implementing several physiological and biochemical mechanisms. Mainly, H2 S helps to implement antioxidant defence systems, and interacts with other molecules like nitric oxide (NO), reactive oxygen species (ROS), phytohormones, etc. These molecules are well-known as the key players that moderate the adverse effects of abiotic stresses. Currently, little progress has been made in understanding the molecular basis of the protective role of H2 S; however, it is imperative to understand the molecular basis using the state-of-the-art CRISPR-Cas gene-editing tool. Subsequently, genetic engineering could provide a promising approach to unravelling the molecular basis of stress tolerance mediated by exogenous/endogenous H2 S. Here, we review recent advances in understanding the beneficial roles of H2 S in conferring multiple abiotic stress tolerance in plants. Further, we also discuss the interaction and crosstalk between H2 S and other signal molecules; as well as highlighting some genetic engineering-based current and future directions.

The oil palm R2R3-MYB subfamily genes EgMYB111 and EgMYB157 improve multiple abiotic stress tolerance in transgenic Arabidopsis plants.

We found that overexpression of EgMYB111 and EgMYB157 genes positively regulate the abiotic stress tolerance. MYB family genes are well-known regulators in modulating the abiotic stress-responsive mechanisms in plants. However, lesser is known about the functional roles of oil palm MYB genes. Previously, we found that oil palm MYB genes such as EgMYB111 and EgMYB157 were significantly up-regulated under salinity, cold, and drought stress conditions. In this study, we over-expressed EgMYB111 and EgMYB157 genes separately in Arabidopsis plants. The transgenic Arabidopsis plants expressing EgMYB111 have shown improved tolerance to salinity, cold and drought stress conditions, whereas transgenic Arabidopsis plants expressing EgMYB157 dispalyed improved tolerance to cold and drought stress conditions only. Various biochemical analyses also revealed significant improvement of antioxidant enzyme activities, photosynthetic pigments, net photosynthetic rate, stomatal conductance, and intercellular CO2 concentration in transgenic plants compared to wild-type plants under cold, drought, and salinity stress conditions. Significant up-regulation of various known stress marker genes such as RD22, RD29A, RAB18, COR47, ABA1, ABI1, HAB1 was also noticed in EgMYB111 and EgMYB157 expressing transgenic plants compared to wild-type plants under cold, drought, and salinity stress conditions. Taken together, over-expression of EgMYB111 and/or EgMYB157 significantly improve abiotic tolerance in transgenic Arabidopsis plants, indicating that EgMYB111 and EgMYB157 are the potential candidates for developing abiotic stress-tolerant crops in near future.

Aldehyde dehydrogenase 3I1 gene is recruited in conferring multiple abiotic stress tolerance in plants.

Plant growth and productivity is restricted by a multitude of abiotic stresses. These stresses negatively affect physiological and metabolic pathways, leading to the production of many harmful substances like ROS, lipid peroxides and aldehydes. This study was conducted to investigate the role of Arabidopsis ALDH3I1 gene in multiple abiotic stress tolerance. Transgenic tobacco plants were generated that overexpress the ALDH3I1 gene driven by the CaMV35S promoter and evaluated under different abiotic stresses, namely salt, drought, cold and oxidative stress. Tolerance to stress was evaluated based on responses of various growth and physiological traits under stress condition. Transgenic plants displayed elevated ALDH3I1 transcript levels compared to WT plants. The constitutive ectopic expression of ALDH3I1 conferred increased tolerance to salt, drought, cold and oxidative stresses in transgenic plants, along with improved plant growth. Transgenic plants overexpressing ALDH3I1 had higher chlorophyll content, photosynthesis rate and proline, and less accumulation of ROS and malondialdehyde compared to the WT, which contributed to stress tolerance in transgenic plants. Our results further revealed that ALDH3I1 had a positive effect on CO2 assimilation rate in plants under abiotic stress conditions. Overall, this study revealed that ALDH3I1 positively regulates abiotic stress tolerance in plants, and has future implications in producing transgenic cereal and horticultural plants tolerant to abiotic stresses.