Reactive oxygen species (ROS) are small molecules produced in plants during the process of energy production. They play crucial roles in plant growth and development, particularly when plants face adverse conditions such as water scarcity or extreme temperatures, which trigger increased ROS levels. Acting as a cellular alarm system, elevated ROS levels serve as signalling molecules within plant cells, prompting internal communication and initiating rescue responses. 

Many plant-specific enzymes, such as respiratory burst oxidase homolog (RBOH), generate ROS in different sub-cellular compartments, including the apoplast (area outside plant cells). Despite the importance of RBOH proteins in numerous biological processes, detailed genome-wide investigations in bread wheat (Triticum aestivum), a major cereal crop, had yet to be conducted towards a comprehensive analysis of these unique proteins.

Recognising this gap, a research group led by Santosh Kumar Upadhyay, Assistant Professor, Panjab University, Chandigarh, conducted a study on RBOH genes in the bread wheat, Triticum aestivum (TaRBOH). Their investigation revealed forty TaRBOH genes, shedding light on their essential characteristics and functions within the complex genetic makeup of bread wheat, with the aim to better understand how they work. 

During this study, the researchers examined the expression of these forty TaRBOH genes at different growth stages of bread wheat and under various stress situations using advanced RNA sequencing and a technique called qRT-PCR. These techniques are powerful and effective in informing scientists about the presence and quantity of RNA molecules in a sample. They can also reveal how active these RNAs are, aiding researchers in understanding what’s going on inside the cells and how different conditions may affect an organisms’ function.

Yashraaj Sharma, the first author of this study, expresses optimism about the agricultural potential of the knowledge gained from this research. He states, 

The synthesis of tiny ROS molecules relies heavily on these RBOH proteins. So, the RBOH enzymes could represent viable options for reaching significant advancements in crop development.

The findings showed that TaRBOH genes play different roles in plant development and stress response. Further, the scientists closely examined the genes, the physical and chemical properties of the proteins they produce, and their evolutionary relationships. They found that these genes exhibit similarity and have been conserved across generations, maintaining stability in their characteristics. This information elucidates certain fundamental and unchanging aspects of the TaRBOH genes. 

The study also analysed the interactions of the TaRBOH genes with other genes inside the plant. Overall, this research lays the groundwork for understanding the functions of the TaRBOH genes, paving the way for more in-depth research. In the future, this could inform genetic engineering efforts aimed at developing crops better equipped to withstand stress, thereby contributing to the cultivation of more resilient and robust plant varieties.

Intrigued by the findings, Upadhyay notes, ​“RBOH proteins are integral components of the plasma membrane and play a crucial role in producing ROS (in the apoplast), which serve as secondary messengers for different biological processes and stress signalling.” He adds,

Despite their significant roles in plants, RBOH characterisation remains incomplete in many important crop plants. So, our objective was to characterise them in bread wheat, an important cereal crop.

Praveen Chandra Verma, Senior Principal Scientist, CSIR-National Botanical Research Institute, Lucknow, who is an expert in the field and was not associated with the study, was impressed with its outcomes. He mentions, ​‘This research could help us in understanding the functions and regulation of RBOHs in crops like wheat. It could indeed pave the way for developing stress-tolerant varieties through targeted genetic modifications or breeding programs.’

RBOHs are vital proteins in plants, and their thorough characterisation in wheat and other crop plants could potentially enhance crop resilience and productivity, contributing to global food security in the face of changing environmental conditions.