Carbohydrate metabolism and activity variation of related enzymes during the exchanging role of bulb source and sink of oriental hybrid lily ‘Sorbonne'

UV spectrophotometer methods were used to assay the carbohydrate contents and activities of related enzymes of oriental hybrid lily ‘Sorbonne爷, and their correlations were analyzed using SPASS. The results showed that: the content of starch in outer and middle scales showed a downward trend from planting to flower bud developing to 3 cm in length, which indicated that the bulb served as source during this process; thereafter to anthesis, the metabolism of starch in the outer and middle scales showed the opposite directions, indicating that the bulbs served as the source-sink complex; from then on, the bulbs became sink to accumulate nutrients. Besides, sucrose and sucrose synthesis enzymes (SS) and sucrose phosphate synthase (SPS) in outer and middle scales showed positive correlations respectively, while starch content and SS and SPS showed negative correlations, all of which were not statistically significant. Furthermore, except that the soluble starch synthase (SSS) and starch content in middle scales showed a low negative correlation, the starch content and the adenosine diphosphate glucose pyrophosphorylase (AGPase), and starch synthase (SSS and granule-bound starch synthase GBSS) in outer and middle scales showed positive correlation, especially the correlation between starch content and SSS and GBSS in the outer scales, which were high positive and significant. Three enzymes relating to starch synthesis showed negative correlation with sucrose content. The activities of enzymes relating to starch synthesis can serve as important references for the source or sink function of lily bulbs. The activities of SSS and GBSS played more significant roles in deciding the sink strength of lily bulbs, which can be used as indicators for the sink strength of lily bulbs.