Abstract
Background
The aleurone layer of endosperm consists of live cells rich in nutrients. Barley is the only cereal which commonly has two or three layers of aleurone cells. Currently little is known about the genetic mechanism and regulatory pathway of aleurone development in this species. To understand aleurone development in barley, we conducted the first transcriptome analysis against barley genotypes differing in aleurone thickness and number of aleurone cell layers.
Results
RNA-seq data from developing grains were collected at four time points during grain filling. Based on analysis of differentially expressed genes, transcription factor (TF) -targeted genes and Weighted Gene Co-expression Networks (WGCNA), we found that the Dof transcription factors, energy-production-related genes and mitochondrial homeostasis genes played vital roles in barley aleurone development. We also found that, during the early gain filling stages, differences in expression level for genes involved in starch and glucan metabolic process, cell wall and plant-type vacuole pathways were mainly responsible for the thickness and the numbers of aleurone cells, and that lipid transport and localization processes contributed to the difference in aleurone thickness at later stages of endosperm development.
Conclusions
In this first study on aleurone development based on transcriptomic analysis in barley, we showed that mechanisms or pathways of aleurone development in this species seemed to be different from those in rice or maize. The thickness and the numbers of aleurone cells in barley seemed to be regulated by different gene networks at different stages of endosperm development.