Agriculture and changing environmental conditions are closely related, as weather changes could adversely affect living organisms or regions of crop cultivation. Changing environmental conditions trigger different abiotic stresses, which ultimately cause the accumulation of reactive oxygen species (ROS) in plants. Common ROS production sites are the chloroplast, endoplasmic reticulum, plasma membrane, mitochondria, peroxisomes, etc. The imbalance in ROS production and ROS detoxification in plant cells leads to oxidative damage to biomolecules such as lipids, nucleic acids, and proteins. At low concentrations, ROS initiates signaling events related to development and adaptations to abiotic stress in plants by inducing signal transduction pathways. In plants, a stress signal is perceived by various receptors that induce a signal transduction pathway that activates numerous signaling networks, which disrupt gene expression, impair the diversity of kinase/phosphatase signaling cascades that manage the stress response in the plant, and result in changes in physiological responses under various stresses. ROS production also regulates ABA-dependent and ABA-independent pathways to mitigate drought stress. This review focuses on the common subcellular location of manufacturing, complex signaling mechanisms, and networks of ROS, with an emphasis on cellular effects and enzymatic and non-enzymatic antioxidant scavenging mechanisms of ROS in Poaceae crops against drought stress and how the manipulation of ROS regulates stress tolerance in plants. Understanding ROS systems in plants could help to create innovative strategies to evolve paths of cell protection against the negative effects of excessive ROS in attempts to improve crop productivity in adverse environments.

The presence of chloroplast-related DNA sequences in the nuclear genome is generally regarded as a relic of the process by which genes have been transferred from the chloroplast to the nucleus. The remaining chloroplast encoded genes are not identical across the plant kingdom indicating an ongoing transfer of genes from the organelle to the nucleus. This review focuses on the active processes by which the nuclear genome might be acquiring or removing DNA sequences from the chloroplast genome. Present knowledge of the contribution to the nuclear genome of DNA originating from the chloroplast will be reviewed. In particular, the possible effects of stressful environments on the transfer of genetic material between the chloroplast and nucleus will be considered. The significance of this research and suggestions for the future research directions to identify drivers, such as stress, of the nuclear incorporation of plastid sequences are discussed. The transfer to the nuclear genome of most of the protein-encoding functions for chloroplast-located proteins facilitates the control of gene expression. The continual transfer of fragments, including complete functional genes, from the chloroplast to the nucleus has been observed. However, the mechanisms by which the loss of functions and physical DNA elimination from the chloroplast genome following the transfer of those functions to the nucleus remains obscure. The frequency of polymorphism across chloroplast-related DNA fragments within a species will indicate the rate at which these DNA fragments are incorporated and removed from the chromosomes.

B-box proteins have emerged as prominent mechanisms for controlling growth and developmental processes and in some instances responses to biotic and abiotic stresses in plants. These proteins mediate transcriptional regulations and protein–protein interactions in cellular signalling processes. B-box proteins thereby play an important role in coordinating physiological and biochemical pathway flux and are therefore ideal targets for controlling stress responses in plants. In this study, the overexpression of anArabidopsis thalianaB-box gene(BBX29)in sugarcane (Saccharumspp. hybrid) has led to enhanced drought tolerance and delayed senescence under water-deficit conditions when compared to the wild-type plants. Transgenic plants maintained a higher relative water content and better protected its photosynthetic machinery. These plants accumulated more proline and displayed enhanced enzymatic antioxidant activity under drought conditions. Overexpression ofAtBBX29further alleviated the build-up of reactive oxygen species and curtailed oxidative damage, resulting in transgenic plants with improved health and higher survival rates during dehydration. Our results suggested that theAtBBX29gene influenced an array of physiological and biochemical mechanisms in sugarcane to the advantage of the crop and might be a target to genetically engineer drought tolerance into sugarcane. This is the first report to elucidate B-box protein functionality in a polyploid crop such as sugarcane.