Plant disease management is key to sustainable production of staple food crops. Calcium (Ca²⁺) signal and phytohormones play critical roles in regulating plant defense responses against pathogens. The Ca²⁺ signals are sensed, decoded and transduced by calmodulin and other Ca²⁺ -binding proteins, followed by interaction with and modulation of activities of target proteins such as calmodulin-binding proteins (CBPs). Members of the Arabidopsis CBP60 gene family, AtCBP60g and AtSARD1, have emerged as major regulators of immune responses. In this study, we identified a 15 member CBP60 gene family in rice (Oryza sativa) of which OsCBP60g-3, OsCBP60g-4, OsCBP60a and OsSARD-like1 genes were consistently upregulated in rice seedlings in response to infection with both fungal (Magnaporthe oryzae) and bacterial (Xanthomonas oryzae) pathogens as well as by salicylic acid (SA). OsCBP60g-4 and OsCBP60g-3 were induced maximally by SA and brassinosteroid (BR), respectively, and OsCBP60g-4 was expressed at 3-fold higher levels in the M. oryzae resistant rice genotype (IC-346004) as compared to the susceptible rice genotype (Rajendra Kasturi). The considerable expansion of the immunity clade and the up-regulation of several OsCBP60 genes in response to pathogens and defense hormones supports the importance of further investigating OsCBP60 genes as targets for increasing disease resistance in rice.

CRISPR/Cas9 genome editing is emerging as a powerful tool for enhancing crop resilience to abiotic and biotic stresses, which continues to challenge agricultural productivity worldwide. Stress factors such as drought, heat, salinity, cold, diseases, pests, and viruses negatively impact crop yields, threatening food security. By precisely editing genes involved in stress response pathways, CRISPR/Cas9 enables the development of crops with enhanced tolerance to these environmental stresses. These innovations mark a significant breakthrough in crop improvement, offering a sustainable approach to combating environmental challenges and boosting agricultural productivity. This book chapter provides a comprehensive overview of the principles of CRISPR/Cas9, its implementation in crop improvement, and its role in enhancing resilience to abiotic and biotic stresses. The chapter discusses the molecular nature of various stresses and how CRISPR/Cas9 technology is used to target specific genes involved in stress responses.

Plants have developed elaborate mechanisms for perceiving extracellular stimuli and subsequently activating defense reactions through a multifaceted interaction of signaling cascades. Calcium ion (Ca²⁺), an essential and ubiquitous intracellular second messenger molecules, whose concentration ([Ca²⁺]cyt) has been observed to rise in response to numerous environmental stresses. The calcium/calmodulin (Ca²⁺/CaM) complex triggers apposite cellular responses through modifying the activities of a varied array of CaM-binding proteins (CBPs). Among CBPs, the CBP60 gene family has been identified as key regulators of stress responses in several crop species. Recently, we have demonstrated the expanded and diversified role of OsCBP60 in rice against devastating pathogens. Here, we analyzed the diversified roles of OsCBP60s in two major abiotic stresses, namely reproductive drought and submergence stress. OsCBP60bcd-2 and OsCBP60g-1/OsSARD1 were consistently upregulated during reproductive drought stress in rice. However, OsCBP60g-5 and OsCBP60g-6 were steadily up-regulated under submergence stress in rice. Interestingly, OsCBP60g-4 was consistently upregulated in both abiotic stresses, except on the third day of reproductive drought. The differential expression of OsCBP60s under water stress highlights the importance of further studying these genes as potential targets for enhancing stress resilience in rice.