| Lycoris radiata is a perennial bulbous plant.The development and expansion of its underground bulb is a complex process of nutrient accumulation,decomposition and re-accumulation.The non structural carbohydrate content and the activity of metabolic enzymes in the underground storage organs of bulb flowers can reflect the level of carbon absorption and consumption in bulb flowers to a large extent.In order to explore the physiological mechanism of ‘flower and leaf do not meet’ in Lycoris radiata,this study focuses on the analysis of the content of non-structural carbohydrate and the activity changes of metabolic enzymes during its development,the purpose of this study to preliminarily reveal the intrinsic nature of its unique biological characteristics from the perspective of ‘supplying-reservoir’ transformation.The main results were as follows:1.At different developmental stages,the contents of starch,soluble sugar,glucose and fructose in bulb changed significantly,but the contents of sucrose did not.The content of starch and sucrose showed a trend of increased first and then decreased from leafing-out stage to flowering stage,both of which reached the peak value at the leaf-withering stage,which indicated that the accumulation of starch in bulb was mainly from leafing-out stage to the stage of leaf-maturity,and the decomposition of starch was mainly at dormancy stage and flowering stage.2.At 6 different developmental stages,the activities of 9 kinds of metabolic enzymes in bulb were significantly different.It was found that the activities of AGP and GBSS were higher in the period of higher starch content in bulb,which indicated that the synthesis of starch was mainly related to AGP and GBSS,while the activities of two sucrose metabolic enzymes(SS and SPS)had different trends,but when the sucrose content reached the peak,the activities of the two enzymes also reached the peak,indicating that the synthesis of sucrose was regulated by the two enzymes together,but mainly SPS.3.In the rapid leaf extension period,the contents of NSC in different vegetative organs(bulbs,leaves and roots)of Lycoris radiata were significantly different.Among them,the starch,soluble sugar,sucrose and fructose contents in the bulb were significantly higher than those in the leaves and roots,while the glucose content in the leaves was significantly higher than that in the roots and bulbs,which indicated that with the enhancement of photosynthesis in the leaves,the starch in the bulb have began to accumulate.In addition,the activities of 9 metabolic enzymes in different vegetative organs were significantly different,but the enzyme activities in leaves were significantly lower than those in bulbs and roots,which also led to the content of 4 NSC indexex in leaves lower than that in bulbs and roots.4.In the dormancy stage,the starch and soluble sugar content in the middle scale were higher than that in the inner and outer scale,which indicated that the outer scale was mainly used as the ‘source’ of energy supply,while the middle scale was used as a‘reservoir’ or standby ‘source’ of energy storage.However,there was no significant difference in starch content among different diameter classes(large,medium and small bulb),which indicated that the size of bulb diameter did not affect bulb starch metabolism at during dormancy.5.The correlation analysis between the contents of 5 NSC indexex and 9 metabolic enzymes in six different growth periods showed that the metabolic enzymes dominate the change of NSC concentration were different in different development periods.The correlation analysis of 5 NSC indexex contents and 9 metabolic enzymes in different organs also showed that the NSC contents in different organs were regulated by many enzymes.However,the starch accumulation in bulb was mainly related to the enzyme activities of AGP and GBSS,while the sucrose accumulation was mainly regulated by SPS. |
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