Gene coexpression analysis reveals dose-dependent and type-specific networks responding to ionizing radiation in the aquatic model plant Lemna minor using public data.

Ionizing radiations (IRs) are widespread damaging stresses to plant growth and development. However, the regulatory networks underlying the mechanisms of responses to IRs remains poorly understood. Here, a set of publicly available transcriptomic data (conducted by Van Hoeck et al. 2015a), in which Lemna minor plants were exposed to a series of doses of gamma, beta and uranium treatments was used to perform gene coexpression network analysis. Overall, the genes involved in DNA synthesis and chromatin structure, light signalling, photosynthesis, and carbohydrate metabolism were commonly responsive to gamma, beta and uranium treatments. Genes related to anthocyanin accumulation and trichome differentiation were specifically downregulated, andgenes related to nitrogen and phosphate nutrition, cell vesicle transport, mitochondrial electron transport and ATP synthesis were specifically upregulated in response to uranium treatment. While genes involved in DNA damage and repair, RNA processing and RNA binding were specifically downregulated and genes involved in calcium signalling, redox and degradation of carbohydrate metabolism were specifically upregulated responding to gamma radiation. These findings revealed both dose-dependent and typespecific networks responding to different IRs in L. minor, and can be served as a useful resource to better understand the mechanisms of responses to different IRs in other plants.

Genome survey sequencing for the characterization of genetic background of Dracaena cambodiana and its defense response during dragon's blood formation.

Dragon's blood collected from the genus Dracaena is used as a renowned traditional medicine in various cultures worldwide. However, the genetics of the genus Dracaena and the formation mechanism of dragon's blood remain poorly understood. Here, we generate the first draft genome reference assembly of an elite Chinese Dracaena species, Dracaena cambodiana, from next-generation sequencing data with 89.46× coverage. The reads were assembled into 2,640,704 contigs with an N50 length of 1.87 kb, and a 1.05 Gb assembly was finally assembled with 2,379,659 scaffolds. Furthermore, 97.75% of the 267,243 simple sequence repeats identified from these scaffolds were mononucleotide, dinucleotide, and trinucleotide repeats. Among all 53,700 predicted genes, 158 genes involved in cell wall and plant hormone synthesis and reactive oxygen species scavenging showed altered regulation during the formation of dragon's blood. This study provides a genomic characterization of D. cambodiana and improves understanding of the molecular mechanism of dragon's blood formation. This report represents the first genome-wide characterization of a Dracaena species in the Asparagaceae.