Comparative Transcriptome Analysis Revealed Candidate Genes Potentially Related to Desiccation Sensitivity of Recalcitrant Quercus variabilis Seeds

Abstract

Background: Chinese cork oak (Quercus variabilis) is a widely distributed and highly valuable deciduous broadleaf tree from both ecological and economic perspectives. Seeds of Q. variabilis are recalcitrant, i.e., sensitive to desiccation, which affects their storage and long-term preservation of germplasm. However, little is known about the underlying mechanism of desiccation sensitivity of Q. variabilis seeds. Results: In this study, the seeds were desiccated with silica gel for 0 day (control, CK), one day (T1) to 15 days (T15). After desiccation, the transcriptomic profiles of these different desiccation stages were compared using the Quercus suber genome as a reference, as well four key stages (CK, T2, T4 and T11) of desiccation sensitivity of Q. variabilis seeds through germination test were identified. A total of 4405, 4441, and 5907 differentially expressed genes (DEGs) were identified in T2 vs CK, T4 vs CK, and T11 vs CK, respectively. Among them, 2219 DEGs were overlapped in the three comparison groups. KEGG (Kyoto Encyclopaedia of Genes and Genomes) enrichment analysis showed that these DEGs were enriched into 124 pathways, such as "plant hormone signal transduction" and "glycerophospholipid metabolism". DEGs related to hormone synthesis and signal transduction (ZEP, YUC, PYR, ABI5, ERF1B, etc), stress response proteins (LEA D-29, HSP70, etc), and phospholipase D (PLD1) were detected during seed desiccation. These genes and their interactions may regulate the desiccation sensitivity of Q. variabilis seeds. Finally, a possible work model was proposed to show the molecular regulation mechanism of desiccation sensitivity in recalcitrant Q. variabilis seedsConclusions: Our study is the first on the molecular regulation mechanism of desiccation sensitivity of Q. variabilis seeds by using RNA-Seq and propose a possible work model. Our findings could make a great contribute to seed storage and long-term conservation of germplasm resources of recalcitrant seeds in the future.

Variation of sugar compounds in Phoebe chekiangensis seeds during natural desiccation

“…Kristina and Sharon [28] found that the sucrose content of cotyledons of Quercus alba was increased in the later stages of drying. The soluble sugar content was increased in recalcitrant seeds of Quercus variabilis [29] during drying.…”