| Jacalin-related lectins (JRLs) are proteins that bind carbohydrates. Functionally, JRLs are thought to be involved in a diverse array of functions including biotic stress defense, intracellular storage, abiotic stress response, and plant development. Recent Arabidopsis thaliana microarray data indicate that a Jacalin-like domain-containing protein (JLL1 ) exhibits highly root specific expression. Previous transcriptomic and proteomic studies indicate that JLL1 may have a dual role in planta as a biotic stress defense protein and in plant development. In order to better understand the physiological function of JLL1 in Arabidopsis, several different analyses were conducted examining its regulatory sequences, spatial expression, responsiveness to abiotic stress, and its impact on seed germination. The results of these investigations reveal that JLL1 exhibits high sequence similarity with two adjacent jacalin domain-containing proteins. The cis-regulatory elements within JLL1's promoter region are largely associated with plant development and metabolism. The spatial expression of JLL1 was localized in the vascular-associated regions of the plant roots, leaf vasculature, and root tip (cap). RTPCR data indicate that JLL1 is negatively regulated during abiotic stress, and JLL1 mutant seeds exhibited delayed germination under abiotic stress conditions. Our data supports the assertion that JLL1 has a dual role in planta as a protein involved in hormone-mediated early plant development, and as a secreted non-specific defense protein. |
