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Drought stress restricts plant growth and development by altering metabolic activity and biological functions. However, plants have evolved several cellular and molecular mechanisms to overcome drought stress. Drought tolerance is a multiplex trait involving the activation of signaling mechanisms and differentially expressed molecular responses. Broadly, drought tolerance comprises two steps: stress sensing/signaling and activation of various parallel stress responses (including physiological, molecular, and biochemical mechanisms) in plants. At the cellular level, drought induces oxidative stress by overproduction of reactive oxygen species (ROS), ultimately causing the cell membrane to rupture and stimulating various stress signaling pathways (ROS, mitogen-activated-protein-kinase, Ca2+, and hormone-mediated signaling). Drought-induced transcription factors activation and abscisic acid concentration co-ordinate the stress signaling and responses in cotton. The key responses against drought stress, are root development, stomatal closure, photosynthesis, hormone production, and ROS scavenging. The genetic basis, quantitative trait loci and genes of cotton drought tolerance are presented as examples of genetic resources in plants. Sustainable genetic improvements could be achieved through functional genomic approaches and genome modification techniques such as the CRISPR/Cas9 system aid the characterization of genes, sorted out from stress-related candidate single nucleotide polymorphisms, quantitative trait loci, and genes. Exploration of the genetic basis for superior candidate genes linked to stress physiology can be facilitated by integrated functional genomic approaches. We propose a third-generation sequencing approach coupled with genome-wide studies and functional genomic tools, including a comparative sequenced data (transcriptomics, proteomics, and epigenomic) analysis, which offer a platform to identify and characterize novel genes. This will provide information for better understanding the complex stress cellular biology of plants.

Background Cotton production is adversely effected by drought stress. It is exposed to drought stress at various critical growth stages grown under a water scarcity environment. Roots are the sensors of plants; they detect osmotic stress under drought stress and play an important role in plant drought tolerance mechanisms. The seedling stage is very sensitive to drought stress, and it needed to explore the methods and plant characteristics that contribute to drought tolerance in cotton. Results Initially, seedlings of 18 genotypes from three Gossypium species: G. hirsutum , G. barbadense, and G. arboreum, were evaluated for various seedling traits under control (NS) and drought stress (DS). Afterward, six genotypes, including two of each species, one tolerant and one susceptible, were identified based on the cumulative drought sensitivity response index (CDSRI). Finally, growth rates (GR) were examined for shoot and root growth parameters under control and DS in experimental hydroponic conditions. A significant variation of drought stress responses was observed across tested genotypes and species. CDSRI allowed here to identify the drought-sensitive and drought-resistant cultivar of each investigated species. Association among root and shoots growth traits disclosed influential effects of enduring the growth under DS. The traits including root length, volume, and root number were the best indicators with significantly higher differential responses in the tolerant genotypes. These root growth traits, coupled with the accumulation of photosynthates and proline, were also the key indicators of the resistance to drought stress. Conclusion Tolerant genotypes have advanced growth rates and the capacity to cop with drought stress by encouraging characteristics, including root differential growth traits coupled with physiological traits such as chlorophyll and proline contents. Tolerant and elite genotypes of G. hirsutum were more tolerant of drought stress than obsolete genotypes of G. barbadense and G. arboreum . Identified genotypes have a strong genetic basis of drought tolerance, which can be used in cotton breeding programs.

Cotton has prime importance in the global economy and governs socio-economic affairs of the world. Water scarcity and high temperature are major constraints that badly affect cotton production, which shows the need for the development of drought-tolerant varieties. Ten cotton genotypes, including three drought-tolerant and seven susceptible, were identified from a panel of diverse cotton genotypes at the seedling stage under two contrasting water regimes. Three lines were crossed with seven testers under line × tester mating design. The 21 F1 cross combinations along with 10 parents were evaluated under 100% non-stress (NS) and 50% drought stress (DS) filed capacity to assess the effects of drought stress and its inheritance in the next generation. All the genotypes were evaluated till the maturity stage for combining ability, heritability, and other genetic factors to understand the drought tolerance mechanisms. The proportional contribution of lines in the total variance evidenced that lines had a significant higher contribution in total variance for days to boll opening (DBO) of 10% and proline contents (PC) of 13% under DS conditions. It indicates that lines contributed more positive alleles for such traits. Under DS condition, DTV-9 × BT-252 and DTV-9 × DTV-10 had maximum negative specific combining ability (SCA) effects for DBO. Simultaneously, DBO also had higher heritability (h2) which indicates its dominant gene action and meanwhile, the importance of these combinations for the early mature and short duration variety development. The results revealed that most of the studied traits, including days taken to maturity, yield traits, and physiological traits, are under significant genetic control, with a strong genetic basis and have a huge potential for improving drought tolerance in cotton. Drought tolerance was found to have a strong association with early maturity and agro-climatic conditions of the cultivated areas. Identified superior parents in this study are suggested to use in the future breeding program to advance the cotton growth and drought tolerance.

Locally developed twenty four sunflower hybrids were appraised for different agronomic traits to assess genetic specifications, genetic divergence, and correlation coefficient, direct and indirect effects of eight characters towards seed yield under field condition. Experiment was conducted according to RCBD design at NARC (National Agricultural Research Centre), Islamabad during year 2015. Data were recorded on Days to flower initiation, Days to flower completion and Days to maturity, 100 seed weight, oil content percentage and Seed Yield. Results of ANOVA revealed that there is remarked variation among all hybrids under study for seed yield and other allied character while non-significant differences were observed for replications except days to flower initiation. In the present study both positive and negative correlations were found between different traits. Days to flower initiation (DFI), days to flower completion (DFC) and days to maturity (DM) contribute positively and highly significantly with plant height (PH) for both genotypic and phenotypic level. Correlation between plant height and oil content was found to be highly significant and positive. Seed yield had positive association but non-significant with DFI, PH 100SW, HD and OC percentage while negative association with DFC and DM. DFI, DFC, HD, 100 SW and OC percentage contribute positively toward seed yield. Present study depicts that for improvement in yield, HD and oil content should be given top priority. Based on WARD’s method genotypes were assigned into seven clusters at 25% linkage distance. Hybrids in Cluster II and IV with high seed yield and oil content were selected as desirable hybrids and suggested to exploit further under diverse environments.

Cotton is a vital resource for the textile industry, but cold stress causes serious problems for it during germination and the early phases of seedling development. Both physiological and molecular strategies cotton employ to withstand cold stress are examined in this article. The antioxidant-mediated defense system, which uses both antioxidants that are enzymatic and those that are not to preserve cellular homeostasis, is one of the important areas. The study delves into the interplay between antioxidant defense systems and membrane integrity, as well as the function of cold-responsive molecules in stressful adaption. The review emphasizes the role that suitable solute, including sugars, and osmoprotectants play in improving cold tolerance. We discuss cold-induced hormonal regulation, focusing on ethylene, and the signaling functions of reactive oxygen species (ROS) in triggering protective responses. Additionally, the synthesis of secondary metabolites like terpenoids and flavonoids as defense mechanisms under cold stress is highlighted. At the molecular level, we explore changes in gene expression and the role of microRNAs in growth regulation, alongside abscisic acid (ABA) in cold stress responses. Adaptation strategies, such as priming and acclimation, are reviewed, emphasizing gene expression changes and metabolic pathways during acclimation. In conclusion, we address methods to improve cotton's resistance to cold, such as biotechnological treatments, selection using markers for tolerance to cold genes, and breeding techniques. Additionally taken into consideration is the use of transcriptomic and proteomics analysis to pinpoint targets for enhancing cold tolerance. Through improved breeding and biotechnology techniques, cotton’s resistance to cold stress may be increased, as this thorough investigation reveals.

Heat stress poses a significant threat to cotton, affecting crucial developmental stages from fertilization to boll development and thereby reducing both yield and quality. As global climate change advances, the likelihood of severe heat waves increases, presenting a serious challenge to agricultural production and our ability to feed a growing population. Cotton’s resilience to heat involves a suite of physiological and biochemical responses, including adjustments in water management and protective mechanisms at the cellular level, such as the synthesis of heat shock proteins (HSPs) and antioxidants. These adaptations are crucial for maintaining cellular integrity and overall plant health under thermal stress. Recent research highlighted specific proteins and enzymes within the plant that help combat stress-related damage. However, the exact molecular mechanisms facilitating these protective responses are not fully delineated. Further research is needed to identify and validate additional molecular mechanisms underlying the plant’s response to heat stress. Additionally, exploring new breeding strategies for the development of more resilient cultivars. In addition, field trials and testing under real-world conditions will be essential to assess the effectiveness of the proposed strategies for mitigating the negative effects of heat stress on crop yields.

Peanut breeding has gained importance gradually by the awareness of the tremendous benefits of this crop from the health and nutritional point of view, arousing considerable production in Pakistan. The pod that encloses the seeds is an economically vital part of the groundnut plant and enhance the market value of groundnut. The experiment was conducted in the Department of Plant Breeding and Genetics, Pir Mehar Ali Shah, Arid Agriculture University, Rawalpindi during Kharif, 2020 with RCBD Design 15 genotypes keeping in view, 15 important yield-related parameters were selected to study under correlation and path analysis. Correlation analysis revealed a significant relation of pod yield with directly contributing yield components like, Peg-1, Pods-1, MPP-1, APL and HSW. In contrast, LA, LLA, PB, SB, MPP-1 and SP were those characters that were in a strong negative association with pod yield. The association of these characters with pod yield indicated the importance of these traits for selecting high yielding genotypes under the screening process. Path analysis revealed a positive direct effect of leaflet area, pods per plant, shelling percentage, average pod length and hundred seed weight. In contrast, leaf area, pegs per plant and mature pods per plant revealed negative direct effect. The mean values for genotypes N0334, abCG005 and BARI-2000 had maximum pod yield per plant among all the genotypes. Biplot and cluster analysis indicated the overall variability among genotypes and degree of genetic diversity. Cluster demonstration also validates the association of parameters revealed in correlation analysis. Thus results provide the information of the association of characters in correlation and split the correlation value into indirect and direct effects of characters to yield, useful for selection of traits in the breeding program.