Role of Germin-Like Proteins (GLPs) in Biotic and Abiotic Stress Responses in Major Crops: A Review on Plant Defense Mechanisms and Stress Tolerance

Germin-like proteins (GLPs) play crucial roles in disease resistance, stress tolerance, and plant defense responses in various crop species. This review explores the intricate role of GLP gene expression and its modulation by cis-acting regulatory elements (CAREs) under biotic and abiotic stress in major crops. In rice, OsGLP2-1 and OsGLP3-7 have been identified as positive regulators of disease resistance. Similarly, TaGLP genes in wheat and VvGLP3 in grapes have been associated with powdery mildew resistance. Additionally, ZmGLP1 in maize and StGLP5 in potato contribute to defense against Bipolaris maydis and salt stress, respectively. AhGLPs in peanuts respond to drought stress, while GmGLP10 in soybean demonstrates a response to Sclerotinia sclerotiorum infection. Research in cotton has unveiled GhABP19 and GhGLP2 as GLPs involved in plant defense responses to wilt disease. Analysis of GLP gene promoters has revealed the presence of stress-responsive CAREs that modulate gene expression under biotic and abiotic stresses. Transgenic overexpression of GLP genes in different plant species, such as potato, tobacco, and Arabidopsis, has resulted in enhanced resistance to fungal pathogens, oxidative stress, and abiotic stresses. CRISPR/Cas9 genome editing has provided insights into UV-B stress response mechanisms. Promising outcomes from transgenic studies and CRISPR genome editing present exciting opportunities to improve disease resistance and stress tolerance in crops. These findings significantly enhance our understanding of the critical roles played by GLPs in crop resilience, paving the way for the development of stress-resistant crops to ensure sustainable global food security.