CRISPR–Cas technology towards improvement of abiotic stress tolerance in plants

Rice Promoter Editing: An Efficient Genetic Improvement Strategy

Gene expression levels in rice (Oryza sativa L.) and other plant species are determined by the promoters, which directly control phenotypic characteristics. As essential components of genes, promoters regulate the intensity, location, and timing of gene expression. They contain numerous regulatory elements and serve as binding sites for proteins that modulate transcription, including transcription factors and RNA polymerases. Genome editing can alter promoter sequences, thereby precisely modifying the expression patterns of specific genes, and ultimately affecting the morphology, quality, and resistance of rice. This paper summarizes research on rice promoter editing conducted in recent years, focusing on improvements in yield, heading date, quality, and disease resistance. It is expected to inform the application of promoter editing and encourage further research and development in crop genetic improvement with promote.

CRISPR-Cas System, a Possible "Savior" of Rice Threatened by Climate Change: An Updated Review

Climate change has significantly affected agriculture production, particularly the rice crop that is consumed by almost half of the world's population and contributes significantly to global food security. Rice is vulnerable to several abiotic and biotic stresses such as drought, heat, salinity, heavy metals, rice blast, and bacterial blight that cause huge yield losses in rice, thus threatening food security worldwide. In this regard, several plant breeding and biotechnological techniques have been used to raise such rice varieties that could tackle climate changes. Nowadays, gene editing (GE) technology has revolutionized crop improvement. Among GE technology, CRISPR/Cas (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein) system has emerged as one of the most convenient, robust, cost-effective, and less labor-intensive system due to which it has got more popularity among plant researchers, especially rice breeders and geneticists. Since 2013 (the year of first application of CRISPR/Cas-based GE system in rice), several trait-specific climate-resilient rice lines have been developed using CRISPR/Cas-based GE tools. Earlier, several reports have been published confirming the successful application of GE tools for rice improvement. However, this review particularly aims to provide an updated and well-synthesized brief discussion based on the recent studies (from 2020 to present) on the applications of GE tools, particularly CRISPR-based systems for developing CRISPR rice to tackle the current alarming situation of climate change, worldwide. Moreover, potential limitations and technical bottlenecks in the development of CRISPR rice, and prospects are also discussed.

Improvement of heat stress tolerance in soybean (Glycine max L), by using conventional and molecular tools

The soybean is a significant legume crop, providing several vital dietary components. Extreme heat stress negatively affects soybean yield and quality, especially at the germination stage. Continuous change in climatic conditions is threatening the global food supply and food security. Therefore, it is a critical need of time to develop heat-tolerant soybean genotypes. Different molecular techniques have been developed to improve heat stress tolerance in soybean, but until now complete genetic mechanism of soybean is not fully understood. Various molecular methods, like quantitative trait loci (QTL) mapping, genetic engineering, transcription factors (TFs), transcriptome, and clustered regularly interspaced short palindromic repeats (CRISPR), are employed to incorporate heat tolerance in soybean under the extreme conditions of heat stress. These molecular techniques have significantly improved heat stress tolerance in soybean. Besides this, we can also use specific classical breeding approaches and different hormones to reduce the harmful consequences of heat waves on soybean. In future, integrated use of these molecular tools would bring significant results in developing heat tolerance in soybean. In the current review, we have presented a detailed overview of the improvement of heat tolerance in soybean and highlighted future prospective. Further studies are required to investigate different genetic factors governing the heat stress response in soybean. This information would be helpful for future studies focusing on improving heat tolerance in soybean.

Improving abiotic stress tolerance in sorghum: focus on the nutrient transporters and marker-assisted breeding

Identification of molecular markers and characterization of nutrient transporters could help to improve the tolerance under abiotic and low nutrient stresses in sorghum ensuring higher yield to conserve food security Sorghum is an important cereal crop delivering food and energy security in the semi-arid tropics of the world. Adverse climatic conditions induced by global warming and low input agriculture system in developing countries demand for the improvement of sorghum to tolerate various abiotic stresses. In this review, we discuss the application of marker-assisted breeding and nutrient transporter characterization studies targeted towards improving the tolerance of sorghum under drought, salinity, cold, low phosphate and nitrogen stresses. Family members of some nutrient transporters such as nitrate transporter (NRT), phosphate transporter (PHT) and sulphate transporter (SULTR) were identified and characterized for improving the low nutrient stress tolerance in sorghum. Several quantitative trait loci (QTL) were identified for drought, salinity and cold stresses with an intention to enhance the tolerance of sorghum under these stresses. A very few QTL and nutrient transporters have been identified and validated under low nitrogen and phosphorus stresses compared to those under drought, salinity and cold stresses. Marker-assisted breeding and nutrient transporter characterization have not yet been attempted in sorghum under other macro- and micro-nutrient stresses. We hope this review will raise awareness among plant breeders, scientists and biotechnologists about the importance of sorghum and need to conduct the studies on marker-assisted breeding and nutrient transporter under low nutrient stresses to improve the sorghum production.