New insights into the molecular mechanism of low-temperature stratification on dormancy release and germination of Saposhnikovia divaricata seeds

Low-temperature stratification has a beneficial effect on releasing seed dormancy and germination. Taking Saposhnikovia divaricata (Trucz.) Schischk. seeds as the research object, the effects of low-temperature stratification on dormancy release and germination of S. divaricata seeds were studied. The morphological, physiological and biochemical indexes, hormone content and transcriptome of dormant seeds, seeds in the dormancy release period and germination period were discussed. The results showed that 4 degrees C low-temperature stratification treatment increased the contents of soluble sugar, gibberellin and indoleacetic acid, enhanced amylase and alpha-amylase activity, but decreased the contents of starch and abscisic acid. A total of 100,690 unigenes were obtained from S. divaricata transcriptome. RNA-seq analysis showed that compared with dormant seeds (CK), the number of up-regulated genes in seeds in the dormancy release period (S) and germination period (G) was 13,998 and 16,817, and the number of down-regulated genes was 9237 and 14,054, respectively. This study identified a large number of differentially expressed genes related to plant hormone signal transduction, starch and sucrose, plant energy metabolism pathway and hormones in low-temperature stratification reaction. The transcriptomic gene expression profiles present a valuable genomic tool to the molecular mechanisms of S. divaricata seed germination underlying low-temperature stratification, which can provide theoretical basis and practical guidance for cultivation and planting of S. divaricata.