Evidence of the predominance of passive symplastic phloem loading and sugar transport with leaf ageing in Camellia oleifera

作     者：Shiwen Yang Kehao Liang Yongjiang Sun Jinshun Zhang Yibo Cao Jing Zhou Aibin Wang Lingyun Zhang Shiwen Yang;Kehao Liang;Yongjiang Sun;Jinshun Zhang;Yibo Cao;Jing Zhou;Aibin Wang;Lingyun Zhang

作者机构：Key Laboratory of Forest Silviculture and Conservation of the Ministry of EducationThe College of ForestryBeijing Forestry UniversityBeijing 100083China 

出 版 物：《Horticultural Plant Journal》 (园艺学报（英文版）)

年 卷 期：2023年第9卷第4期

页      面：811-825页

核心收录：

学科分类：0907[农学-林学] 08[工学] 0829[工学-林业工程] 09[农学] 

基　　金：supported by grants from National Natural Science Foundation of China(grant number 32071798 to L.Y.Z) 

主　　题：Camellia oleifera Phloem loading Leaf Sugar transport Yield formation 

摘      要：Phloem loading and transport of sugar from leaves to sink tissues such as fruits are crucial for yield *** oleifera is an evergreen horticultural crop with high value;however,its low production limits the development of the *** *** this study,using a combination of ultrastructural observation,fluorescence loss in photobleaching(FLIP)and inhibitor treatment,we revealed that *** leaves mainly adopt a symplastic loading route from mesophyll cells to the surrounding vascular bundle cells in minor *** assays showed that sucrose is the main sugar transported and only a small amount of raffinose or stachyose was detected in petioles,supporting a passive symplastic loading route in *** *** to leaves grown this year(LT),the carbohydrate synthesis capacity in leaves grown last year(LL)was decreased while LL retained more soluble sugar,suggesting a decrease in transport capacity with leaf *** and tissue staining showed that a reduction in plasmodesmata density leads to a decline in the degree of cellular coupling and is responsible for the weakening transport capacity in older ***-seq revealed several differentially expressed genes(DEGs)including CoPDCB1-1,CoSUT1 and CoSWEET12,which are likely involved in the regulation of phloem loading and sugar *** expression correlation network is constructed between PD-callose binding protein genes,sugar transporter genes and senescence-associated ***,this study provides the evidence of the passive symplastic phloem loading pathway in *** leaves and constructs the correlation between sugar transport and leaf ageing.