Project description:In rice, gene expression profiling under different stresses have been carried out earlier through microarrays and SAGE (Kawasaki et al., 2001; Rabbani et al., 2003,;. Yazaki et al., 2003, 2004; Walia et al., 2005; Zhou et al., 2005; Jiao et al., 2005; Zhou, 2007; Wang, et al., 2007)). The results reported so far were mostly derived from different stress treatments, array formats, species, tissue types, and time courses, which make it difficult for direct comparison among studies. Also, most of the stress experiments on expression profiles were conducted under laboratory, growth chamber or field grown plants subjected to stress in laboratory conditions, usually by inducing stress with exogenous compounds such as abscisic acid (ABA) or gibberellin (GA) genes (Yazaki et al., 2003, 2004; Rabbani et al., 2003), salt (Kawasaki et al., 2001; Rabbani et al., 2003; Walia et al., 2005), organ specific gene expression under high salinity (Jiao et al., 2005) and drought (Zhou et al., 2007), comparison with different cultivars (Wang et al., 2007) and other environmental stresses such as cold and drought (Rabbani et al., 2003; Zhou et al., 2005). However, such laboratory, growth chamber grown plants or field grown plants subjected to stress under laboratory conditions significantly differ from the field stress conditions and therefore the resultant plant response may not truly represent the actual stress conditions prevailing on field. This has been extensively reviewed by Mittler, 2006 and the need for utilizing data from multiple stress experiments for developing plants resistant to stress has been focused. The review also focuses on evaluating farmers experiences in stress management and kinds of stress that a plant is subjected prior to taking up research on stress resistances has been of significant importance. In the present study, to bridge the gap between the available data on drought stress and the gene regulation under field drought conditions has been paid attention. The outcome of this data will give new leads for breeders to design strategies to develop plants resistant to drought without much loss in yield. In the present study experiments were conducted under different field capacities using a rainout shelter to minimizing the effects of drought induction due to rains. The microarray analysis is thus expected to throw light on stress responsive gene expression in field drought conditions. Till now, to our knowledge there have been no reports on gene expression in rice under field drought conditions. Further, there is no data available on gene expression profiling during various stages of plant growth in leaf and panicle tissues under different levels of water stress. Here, we have focused on generating stress responsive gene (SRG) expression profiles in field drought conditions through the entire life cycle of rice plant. Optimal drought simulation was achieved by conducting a drought stress experiment and validated by a series of dry runs. The main reason for evaluating gene expression under drought in field condition is as drought itself is not limited to water stress but various other factors, such as heat, humidity, hot winds, and long day lengths effect the gene regulation. All these are likely to trigger common pathways that are also a part of drought stress response and therefore significantly affect the expression profiles. In the present study, field drought stress was initiated from 31 days after germination and transplantation to the field at 100%, 60%, 40% and 15% field capacities designated as A1, A2, A3, and A4. It took 7 days for the onset of the actual drought for the experimental plots to reach to their designated field capacities from 100% FC. Samples were collected from 7 days after drought stress to 33 days after drought stress to evaluate different drought stress regimes based on the developmental stages of the plant. At all the tested stress levels the data points were Hierarchically grouped and clustered sets of genes were examined and an approximate number of clusters to be formed were estimated. Finding a group of genes showing a similar pattern of gene expression by means of expression data from microarray analysis is the basis for identification of genes and pathways controlling a specific trait. We have followed unsupervised classification and clustered the genes hierarchically after normalizing expression data to obtain a set of co-regulated genes. Analysis of data revealed that there are at least 3 to 4 clusters which show differential regulation under each stress regime. The annotated genes falling in these clusters interestingly include a number of novel genes from N22 library along with some known candidate genes for drought tolerance which were earlier identified in our study (Markandeya et al., 2007). Expression pattern of these genes from 7 days after drought stress to 33 days after drought stress with their fold changes were evaluated in the present study. In particular, it is observed that many genes of unknown function are also co-regulated in an interesting pattern along with known genes.

Project description:The urgent need to address water scarcity underscores the importance of enhancing plant drought resistance. This study investigates whether pretreatment with abscisic acid (ABA) activates early stress signaling, thereby improving barley drought response when subsequently exposed to drought conditions. Although the individual responses to drought and ABA are well-documented, their synergistic effects in barley warrant further investigation. This study examines the impact of ABA on barley drought resilience through an experimental design that incorporates four distinct treatments: optimal watering, ABA application at 60 days post-sowing, and two drought stress treatments - one with and the other without prior ABA application. Key physiological parameters, such as photosynthesis, stomatal conductance and chlorophyll content, were analyzed in conjunction with transcriptomics. The results suggest that ABA pretreatment initiates early stomatal closure and elevates the expression of essential genes like NCED1, BG8, and HvA22, priming barley for improved drought resistance. During the drought, ABA-pre-treated barley maintained high chlorophyll levels, indicating sustained photosynthetic activity, a trend that persisted across treatments during the post-drought recovery phase. Furthermore, ABA pre-treatment was found to preserve photosystem II efficiency during drought conditions. Transcriptomic analyses revealed distinct gene expression profiles, alternative splicing profile and isoform switching, highlighting the molecular complexities of ABA role in drought response. These alterations span stress response, metabolic pathways, and DNA modification processes, providing a comprehensive view of ABA treatment's regulatory and metabolic impacts. In conclusion, ABA pretreatment strengthens barley drought defense by fostering stomatal closure and gene activation, guiding research strategies grounded in ABA and suggesting that genotypes with elevated ABA levels could have enhanced resilience and recovery capabilities.

Project description:Female Aedes aegypti mosquitoes impose a severe global public health burden as primary vectors of multiple viral and parasitic pathogens. Under optimal environmental conditions, Aedes aegypti females have access to human hosts that provide blood proteins for egg development, conspecific males that provide sperm for fertilization, and freshwater that serves as an egg-laying substrate suitable for offspring survival. As global temperatures rise, Aedes aegypti females are faced with climate challenges, like intense droughts and intermittent precipitation, which create unpredictable and suboptimal conditions for the egg-laying step of their reproductive cycle. Aedes aegypti mosquitoes nonetheless show remarkable reproductive resilience, but how they achieve this is unknown. Here we show that under drought-like conditions simulated in the laboratory, mated, blood-fed Aedes aegypti females carrying mature eggs retain them in their ovaries for extended periods, while maintaining the viability of these eggs until they can be deposited in freshwater. Using transcriptomic and proteomic profiling of Aedes aegypti ovaries, we identify two previously uncharacterized genes – here named tweedledee and tweedledum – that show ovary-enriched, temporally-restricted expression during egg retention. These genes are mosquito-specific, linked within a syntenic locus, and rapidly evolving under positive selection, raising the possibility that they serve an adaptive function. Using loss-of-function mutagenesis to disrupt both genes, we show that, tweedledee and tweedledum, which encode secreted proteins, are specifically required for extended retention of viable eggs, such as during intermittent precipitation or drought. These results highlight an elegant example of taxon-restricted genes at the heart of an important adaptation that equips Aedes aegypti females with “insurance” to, when contextually appropriate, flexibly extend their reproductive sequence without losing reproductive capacity, thus allowing this species to exploit diverse and unpredictable/chaotic/changing habitats.

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Soil Microbiome Resilience Under Drought Conditions

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