Transcriptome and metabolome analyses revealing the potential mechanism of seed germination in Polygonatum cyrtonema

Abstract

Background: Polygonatum cyrtonema Hua is a Chinese traditional medicine in the Liliaceae family. It have unique medical and edible value. However, the Polygonatum cyrtonema seeds are naturally difficult to germinate. Its reproductive and growth cycles should be accelerated through artificial technologies for meeting the market demand. Therefore, to beak the seeds dormancy and to elucidate the mechanism of germination, the metabolomics and transcriptomics analysis were performed in this study. Results: The results indicate that plant hormone (auxin, GA, ABA) were involved in seed germination. Furthermore, the expression levels of unigenes and α-amylase activity were increased in germinated seeds. In addition, the metabolites of phenylpropanoid and flavonoid biosynthesis were accumulated in Polygonatum cyrtonema seeds. Hhydroxycinnamyl (caffeic acid, coniferin and sinapic acid et al.), organic acids (benzoic acid, ferulic acid, and coumaric acid etc.) were significantly decreased, while flavonoids significantly accumulated during the germination. The results suggest that the metabolites of germinated seeds were mainly to promote flavonoids synthesis and to inhibit the lignin synthesis, which was beneficial to germination of Polygonatum cyrtonema. And hydrolysis of starch to glucose can provides necessary energy for germination. Conclusions: Our results give a novel insights into the regulating networks of seed germination and pave the way for Polygonatum cyrtonema seeds propagation and cultivation.

Revealing the mechanisms of the bioactive ingredients accumulation in Polygonatum cyrtonema by multiomics analyses

“…P. cyrtonema , known as “longevity grasses”, is one of the traditional Chinese medicinal materials with homology of medicine and food published by the National Health Commission, as well as the traditional bulk medicinal materials in China ( Zhao et al., 2018 ; Zhang et al., 2020 ; Zhang et al., 2021 ; Zhang et al., 2022 ). The dried rhizome of the herb P. cyrtonema has a variety of bioactive ingredients (polysaccharides, saponins, and flavonoids), which have been used mainly as vegetables, food, and medicine over the years with many beneficial effects, including treating cough, antiaging, and anti-inflammatory effects ( Liao and Wu, 2021 ; Liu et al., 2021 ). Although a previous study showed that 637 metabolites were detected in P. cyrtonema seeds by LC/MS, no relevant in-depth study has reported the differences and expression profiles in DAMs in different tissues of P. cyrtonema ( Liu et al., 2021 ).…”

“…The dried rhizome of the herb P. cyrtonema has a variety of bioactive ingredients (polysaccharides, saponins, and flavonoids), which have been used mainly as vegetables, food, and medicine over the years with many beneficial effects, including treating cough, antiaging, and anti-inflammatory effects ( Liao and Wu, 2021 ; Liu et al., 2021 ). Although a previous study showed that 637 metabolites were detected in P. cyrtonema seeds by LC/MS, no relevant in-depth study has reported the differences and expression profiles in DAMs in different tissues of P. cyrtonema ( Liu et al., 2021 ). In this study, 349 metabolites were successfully detected in roots, rhizomes, stems, and leaves by UPLC-MS/MS.…”

“…Polygonatum cyrtonema is a kind of medicinal and edible herb belonging to the genus Polygonatum (comprising ~70 species) within the family Liliaceae, which was incorporated into the Chinese Pharmacopoeia by 2020 together with P. sibiricum , P. kingianum , and P. odoratum ( Zhao et al., 2018 ; Zhang et al., 2020 ; Zhang et al., 2021 ; Zhang et al., 2022 ). The rhizome of P. cyrtonema has the functions of moistening the lung, replenishing qi, invigorating the spleen, nourishing yin, and reinforcing the kidney and has been widely applied to treat various diseases for more than 2000 years in Asia ( Liu et al., 2021 ; Liao and Wu, 2021 ). Modern pharmacological studies have shown that the rhizome of P. cyrtonema is rich in polysaccharides, steroidal saponins, flavonoids, and alkaloids, which have multiple biological activities, including antimicrobial, regulating blood lipids, antiaging, lowering blood sugar, and anti-inflammatory activity ( Zhao and Li, 2015 ; Ma et al., 2019 ; Liao et al., 2020 ; Wu et al., 2022 ).…”

“…reported that the main factor affecting the growth of P. cyrtonema was the monthly precipitation based on MaxEnt and the distribution range of literature records ( Zhang et al., 2021 ). Most of the seed germination inhibitors from P. cyrtonema could inhibit root growth, chlorophyll synthesis and water absorption, and a GA3 concentration of 0.3 mg/L exerted an antagonistic effect on the germination inhibitor ( Liu et al., 2021 ). The polysaccharides extracted from P. cyrtonema had good hypoglycemic and antiosteoporosis effects on a model of juvenile zebrafish with type 2 diabetes and osteoporosis ( Fan et al., 2020 ).…”

“…Transcriptome sequencing was used to identify candidate genes associated with polysaccharides accumulation in P. cyrtonema ( Wang et al., 2019 ). Integrated transcriptome and metabolome analysis found that germinated seeds could inhibit lignin synthesis, which is beneficial to the germination of P. cyrtonema seeds ( Liu et al., 2021 ). Transcriptome analysis of the rhizome of P. cyrtonema identified 27 encoded enzymes associated with steroidal saponins biosynthesis ( Liao et al., 2020 ).…”