Dynamic Transcriptome in Limonium bicolor Leaf Development: Insights into Genes Controlling Salt Gland Differentiation. Limonium bicolor

The salt glands in the epidermis of recretohalophytes play a pivotal role in salt tolerance by secreting excess salts from tissues. Irrespective of the importance of understanding the secretion process, nothing is known about the molecular mechanisms of salt gland development. Limonium bicolor possesses multi-cellular salt glands in the epidermis and provides a model to study salt gland development. We applied next-generation sequencing to profile early leaf development using five distinctly different developmental stages, which were quantified by successive collections of the first true leaf of L. bicolor with precise spatial and temporal resolution. Twenty-two percent of the genes were differentially expressed along the developmental gradient. Cluster analysis revealed specific expression patterns at one stage, and identified enriched functions specific for each developmental stage. Seventy-two genes were identified as highly involved in salt gland differentiation. Salt glands have high homology with trichomes, which was also confirmed by mutants with increased salt gland densities. A model is proposed to illustrate genes participating in salt gland differentiation. This unique dataset lays the foundation for identifying key genes involved in salt gland development and salt secretion, which is a requisite for understanding mechanisms that could make agriculture possible in saline areas worldwide. Overall design: Five samples were analyzed as stage A, B, C, D and E. Each sample were sequenced in two different lines for biological replicates.