Water deficit caused by drought is a significant threat to crop growth and production. Nitric oxide (NO), a water- and lipid-soluble free radical, plays an important role in cytoprotection. Apart from a few studies supporting the role of NO in drought responses, little is known about this pivotal molecular amendment in the regulation of abiotic stress signaling. In this review, we highlight the knowledge gaps in NO roles under drought stress and the technical challenges underlying NO detection and measurements, and we provide recommendations regarding potential avenues for future investigation. The modulation of NO production to alleviate abiotic stress disturbances in higher plants highlights the potential of genetic manipulation to influence NO metabolism as a tool with which plant fitness can be improved under adverse growth conditions.

Climate change poses a serious threat to global agricultural activity and food production. Plant genome editing technologies have been widely used to develop crop varieties with superior qualities or can tolerate adverse environmental conditions. Unlike conventional breeding techniques (e.g., selective breeding and mutation breeding), modern genome editing tools offer more targeted and specific alterations of the plant genome and could significantly speed up the progress of developing crops with desired traits, such as higher yield and/or stronger resilience to the changing environment. In this review, we discuss the current development and future applications of genome editing technologies in mitigating the impacts of biotic and abiotic stresses on agriculture. We focus specifically on the CRISPR/Cas system, which has been the center of attention in the last few years as a revolutionary genome-editing tool in various species. We also conducted a bibliographic analysis on CRISPR-related papers published from 2012 to 2021 (10 years) to identify trends and potential in the CRISPR/Cas-related plant research. In addition, this review article outlines the current shortcomings and challenges of employing genome editing technologies in agriculture with notes on future prospective. We believe combining conventional and more innovative technologies in agriculture would be the key to optimizing crop improvement beyond the limitations of traditional agricultural practices.

The R2R3-MYB genes regulate pigmentation and morphogenesis of flowers, including flower and cell shape, and therefore have importance in the development of new varieties of orchids. However, new variety development is limited by the long breeding time required in orchids. In this study, we identified a cDNA, DhMYB1, that is expressed during flower development in a hybrid orchid, Dendrobium hybrida (Dendrobium bobby messina X Dendrobium chao phraya) then used the direct application of dsRNA to observe the effect of gene silencing on flower phenotype and floral epidermal cell shape. Flower bud development in the Dendrobium hybrid was characterised into seven stages and the time of meiosis was determined as between stages 3 to 5 when the bud is approximately half of the mature size. Scanning electron microscopy characterisation of adaxial epidermal cells of the flower perianth, showed that the petals and sepals each are divided into two distinct domains based on cell shape and size, while the labellum comprises seven domains. Thirty-two partial cDNA fragments representing R2R3-MYB gene sequences were isolated from D. hybrida. Phylogenetic analysis revealed that nine of the translated sequences were clustered with MYB sequences that are known to be involved in cell shape development and from these, DhMYB1 was selected for full length cDNA cloning and functional study. Direct application of a 430 bp dsRNA from the 3’ region of DhMYB1 to emerging orchid flower buds reduced expression of DhMYB1 RNA compared with untreated control. Scanning electron microscopy of adaxial epidermal cells within domain one of the labellum of flowers treated with DhMYB1 dsRNA showed flattened epidermal cells whilst those of control flowers were conical. DhMYB1 is expressed throughout flower bud development and is involved in the development of the conical cell shape of the epidermal cells of the Dendrobium hybrida flower labellum. The direct application of dsRNA changed the phenotype of floral cells, thus, this technique may have application in floriculture biotechnology.

Cymbidium mosaic virus (CymMV) is one of the most prevalent viruses infecting and causing damage to orchids. As tissue culture methods are widely used for commercial orchid production, CymMV infection commonly occurs during transplantation and pruning, so the protection of plants during these stages would be of value to the industry. Double-stranded RNA (dsRNA) has been shown to mediate gene silencing via mRNA degradation and the inactivation of both endogenous and virally-expressed genes in plants. In this study, crude bacterial extracts were prepared from an RNase-deficient strain of Escherichia coli, HT115 (DE3), that expressed sense or anti-sense RNA corresponding to the CymMV coat protein gene (CP). A mixture of sense and anti-sense CP RNAs were used to produce dsRNA. Exogenous sense or anti-sense RNA introduced into the leaves of Brassolaeliocattleya hybrida by mechanical inoculation reduced the symptoms of CymMV infection and reduced expression of the CymMV CP RNA in virus-infected plants three-fold (with sense ssRNA) and over seven-fold (with anti-sense ssRNA) compared to the levels in virus-infected control plants with no ssRNA treatment. Most orchid plants infected with CymMV and treated with CymMV CP dsRNA, showed no symptoms of CymMV infection. The levels of expression of the CymMV CP gene in CymMV CP dsRNA-treated plants were 40-fold lower than in virus-infected control plants and similar to the CP RNA levels detected by quantitative RT-PCR in uninfected control orchid plants. These results demonstrate that the application of a crude extract of bacterially-expressed ssRNA or dsRNA corresponding to the CymMV CP gene was able to reduce viral symptoms and levels of CymMV CP RNA in infected orchids. This approach could provide a relatively low-cost method to protect orchid plants during commercial transplantation from tissue culture.

Abiotic stresses such as drought, heat, salinity, and heavy metal contamination severely affect global agricultural productivity. Between 2005 and 2015, droughts caused losses of approximately USD 29 billion in developing cou... | Find, read and cite all the research you need on Tech Science Press