Abstract:

Objective The effect of Ca^{2 +} on the germination characteristics of flax (Linum usitatissimum L.) seeds was identified, and the regulation mechanism of flax seed germination was deeply understood, which may provide a theoretical basis for flax seed germination and new insights for further understanding the influence of Ca^{2 +} on flax seed germination. Method The seeds of the flax variety Jinya 10 were treated with a 0.5% calcium chloride solution and then dried in air for germination experiment. Bioinformatics was used to analyze the expressions of genes before and after Ca^{2 +} treatment at 5, 10 and 15 h. Result The time of dew-white and budding of flax seeds treated with Ca²⁺ was significantly advanced. Transcriptome sequencing was utilized to analyze gene expression before and after Ca²⁺ treatment at 5, 10, and 15 h time points. Following a 5-hour Ca^{2 +} retreatment of the flax seeds, a total of 1 357 differentially expressed genes were identified compared to the control group, with 558 genes upregulated and 799 genes downregulated. As the duration of Ca^{2 +} treatment extended, the number of differentially expressed genes significantly decreased. After a 10-hour Ca²⁺ treatment, a total of 641 differentially expressed genes were discovered, with 385 upregulated and 256 downregulated. When the flax seeds were treated with Ca^{2 +} for 15-hour, only 168 genes showed differential expression compared to the control, of which 151 were upregulated and 17 were downregulated. Gene co-expression network analysis was employed to select the most relevant modules and hub genes in each group. Conclusion In the H5 group (seeds treated with Ca²⁺ for 5 h), the Meblue module was significantly associated, a total of 147 genes were identified and enriched in the pathways of carbon metabolism, plant hormone signaling transduction and carbon fixation in photosynthetic organisms. The Mebrown module in the H15 group (seeds treated with Ca²⁺ for 15 h) contained a total of 141 genes, which were enriched in carbon metabolism pathway, phenylpropanoid biosynthesis pathway and linolenic acid metabolism pathway. Furthermore, 35 genes related to plant hormone signal transduction pathways in flax seeds are specifically selected for differential expression due to Ca^{2 +} treatment.

Key words: transcriptome, flax, seed germination, Ca²⁺, differentially expressed gene, core gene, phenotypic change, plant hormone signaling pathway