Structural, genetic, and adaptive basis of superhydrophobicity in rice leaves

In most plants, leaf surfaces exhibit water-repellent properties, which protect against pathogens and weather. Plants such as lotus and rice have evolved outstanding water-repellent properties, so-called superhydrophobicity. However, the structural and genetic basis of these properties in crop plants remains unclear. In this study, we identified the genes and microstructures responsible for superhydrophobicity by analyzing water repellence in rice mutants and cultivars, as well as wild Oryza species. Analysis of the surface structure of mutant leaves revealed that the degree of water repellency in rice largely depends on the accumulation of cuticular wax. Meanwhile, although papillae differentiation contributes minorly to water repellency, it is suggested to play a crucial role in achieving superhydrophobicity. These morphological characteristics are regulated by at least five previously characterized genes. We also found that superhydrophobicity is present in ancestral species, is retained by most cultivated rice, and appears to have evolved independently of rice domestication. Understanding the mechanisms of water repellence and their applications should provide important insight into the natural design of water repellence, as well as a basis for future innovation.