Starch–sucrose metabolism and phenylpropanoid biosynthesis pathways play crucial regulatory roles in extending the postharvest longevity of Lilium brownii var. viridulum bulbs

Abstract

The short shelf life of Lilium brownii var. viridulum bulbs after harvesting limits its market supply capacity and makes it difficult to meet customer demand. Therefore, it is particularly important to effectively extend the fresh-eating period of Lilium brownii var. viridulum. In this study, Lilium brownii var. viridulum was used as experimental material and metabolomics and transcriptomics techniques were employed. A total of 883 metabolites and 9452 differentially expressed genes were detected, primarily enriched in secondary metabolite biosynthesis, phenylpropanoid biosynthesis, and starch–sucrose metabolism pathways. Further analyses showed that the accumulation of cellulose had a positive effect on maintaining the cellular structure and morphology of the Lilium brownii var. viridulum bulbs. The reduction of vicianose may be related to the energy expenditure associated with maintaining internal metabolism in Lilium brownii var. viridulum bulbs after postharvest. The low temperature and hypobaric conditions could slow down the increase of reducing sugars, reduce the metabolic rate of sucrose, maintain the relative stability of trehalose, and improve the resistance of bulbs. Ferulic acid was not consumed in large quantities and flavonoids were not over-accumulated, effectively maintaining the stability of the epidermal colour of the bulbs. Meanwhile, the increased expression of LbSUS4, LbINV2, and LbTPP genes could enhance the cold tolerance of Lilium brownii var. viridulum bulbs, stabilise the cell membrane and protect the cell structure to adapt to changes in environmental conditions. In conclusion, bulbs stored under low temperature and hypobaric conditions showed minimal changes in metabolites, and their morphology and color were maintained for a longer duration. This method proves to be suitable for the rapid postharvest storage of Lilium brownii var. viridulum bulbs. This study provides new insights into the molecular regulatory mechanisms during postharvest storage of Lilium brownii var. viridulum bulbs and offers theoretical and technical support for extending their fresh-eating period.