Amid apprehension of global climate change, crop plants are inevitably confronted with a myriad of abiotic stress factors during their growth that inflicts a serious threat to their development and overall productivity. These abiotic stresses comprise extreme temperature, pH, high saline soil, and drought stress. Among different abiotic stresses, drought is considered the most calamitous stressor with its serious impact on the crops' yield stability. The development of climate-resilient crops that withstands reduced water availability is a major focus of the scientific fraternity to ensure the food security of the sharply increasing population. Numerous studies aim to recognize the key regulators of molecular and biochemical processes associated with drought stress tolerance response. A few potential candidates are now considered as promising targets for crop improvement. Transcription factors act as a key regulatory switch controlling the gene expression of diverse biological processes and, eventually, the metabolic processes. Understanding the role and regulation of the transcription factors will facilitate the crop improvement strategies intending to develop and deliver agronomically-superior crops. Therefore, in this review, we have emphasized the molecular avenues of the transcription factors that can be exploited to engineer drought tolerance potential in crop plants. We have discussed the molecular role of several transcription factors, such as basic leucine zipper (bZIP), dehydration responsive element binding (DREB), DNA binding with one finger (DOF), heat shock factor (HSF), MYB, NAC, TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP), and WRKY. We have also highlighted candidate transcription factors that can be used for the development of drought-tolerant crops. | INTRODUCTIONThe molecular and biochemical homeostasis is essential for taking multiple, yet precise, decisions for systematized cellular growth and development in any organism. These processes' functioning is deregulated when exposed to an unfavorable environmental condition that results in the transition of the appropriate growth phase progression into the survival mode (Zhu, 2016). The unfavorable environmental factors that impose a damaging impact on crop productivity can be termed as stress. Based on the agents that impose stress on the

Abstract Silicon is widely recognized as a beneficial element for plant growth. Numerous studies have shown the beneficial effects of silicon, particularly under stress conditions. For the efficient exploration of silicon derived benefits, understanding silicon uptake mechanism, subsequent transport and accumulation in different tissues is essential. Here, a thorough review of reports describing how plants benefit from silicon supplementation was performed to provide comprehensive and clear insights. The molecular mechanism involved in silicon transport has been discussed and highlighted the knowledge gap, particularly the xylem unloading and transport in heavily silicified cells. Silicification of plant tissues like sclerenchyma, fibers, storage tissues, epidermal, and vascular tissues have been described. Silicon deposition in different cell-types, tissues, and intercellular spaces impacting morphological and physiological status found to be associated with enhanced plant resilience under various stresses. The beneficial impact of silicon deposition under various biotic and abiotic stresses has been addressed in detail. Among the mechanisms discussed here to explain silicon derived benefits, most profoundly observed includes interference in physiological processes, modulation of stress responses, and biochemical interactions. Understanding different mechanisms specific to silicon deposition in tissues, developmental stages, and environmental factors will be helpful to elucidate the versatile role of silicon in plants.

No abstract

Silicon, a quasi‐essential element for plants, improves vigour and resilience under stress. Recently, studies on textile hemp (Cannabis sativa L.) showed its genetic predisposition to uptake silicic acid and accumulate it as silica in epidermal leaf cells and trichomes. Here, microscopy, silicon quantification and gene expression analysis of candidate genes involved in salt stress were performed in hemp to investigate whether the metalloid protects against salinity. The results obtained with microscopy reveal that silicon treatment ameliorated the symptoms of salinity in older fan leaves, where the xylem tissue showed vessels with a wider lumen. In younger ones, it was difficult to assess any mitigation of stress symptoms after silicon application. At the gene level, salinity with and without silicon induced the expression of a putative Si efflux transporter gene 2 (low silicon 2, Lsi2). The addition of the metalloid did not result in any statistically significant changes in the expression of genes involved in stress response, although a trend towards a decrease was observed. In conclusion, our results show that hemp stress symptoms can be alleviated in older leaves by silicon application, that the metalloid is accumulated in fan leaves and highlight one putative rice Lsi2 orthologue as responsive to salinity.

Silicon (Si) is widely accepted as a beneficial element for plants. Despite the substantial progress made in understanding Si transport mechanisms and modes of action in plants, several questions remain unanswered. In this review, we discuss such outstanding questions and issues commonly encountered by biologists studying the role of Si in plants in relation to Si bioavailability. In recent years, advances in our understanding of the role of Si-solubilizing bacteria and the efficacy of Si-nanoparticles have been made. However, there are many unknown aspects associated with structural and functional features of Si transporters, Si loading into the xylem, and the role of specialized cells like silica cells and compounds preventing Si polymerization in plant tissues. In addition, despite several thousand reports showing the positive effects of Si in high as well as low Si-accumulating plant species, the exact roles of Si at the molecular level are yet to be understood. Some evidence suggests that Si regulates hormonal pathways and nutrient uptake, thereby explaining various observed benefits of Si uptake. However, how Si modulates hormonal pathways or improves nutrient uptake remains to be explained. Finally, we summarize the knowledge gaps that will provide a roadmap for further research on plant silicon biology, leading to an exploration of the benefits of Si uptake to enhance crop production.

No abstract

No abstract

No abstract