Low humic acids promote in vitro lily bulblet enlargement by enhancing roots growth and carbohydrate metabolism

作     者：Yun WU Yi-ping XIA Jia-ping ZHANG Fang DU Lin ZHANG Yi-di MA Hong ZHOU 

作者机构：Department of Horticulture College of Agriculture and Biotechnology Zhejiang University College of Horticulture Shanxi Agricultural University 

出 版 物：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 (浙江大学学报（英文版）B辑（生物医学与生物技术）)

年 卷 期：2016年第17卷第11期

页      面：892-904页

核心收录：

学科分类：090706[农学-园林植物与观赏园艺] 0907[农学-林学] 09[农学] 

基　　金：Project supported by the National High-Tech R&D Program(863) of China(No.2011AA100208) the Zhejiang Provincial Natural Science Foundation of China(No.LY12C15003) 

主　　题：Bulblet development Humic acid Starch metabolism Source-sink conversion Lilium Oriental Hybrids ‘Sorbonne' 

摘      要：Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable condition to explore bulb growth. The present study was conducted to investigate the effects of humic acid （HA） on bulblet swelling and the carbohydrate metabolic pathway in Li/ium Oriental Hybrids ＇Sorbonne＇ under in vitro conditions. HA greatly promoted bulblet growth at 0.2, 2.0, and 20.0 mg/L, and pronounced increases in bulblet sucrose, total soluble sugar, and starch content were observed for higher HA concentrations （_〉2.0 mg/L） within 45 d after transplanting （DAT）. The activities of three major starch synthetic enzymes （including adenosine 5＇-diphosphate glucose pyro- phosphorylase, granule-bound starch synthase, and soluble starch synthase） were enhanced dramatically after HA application especially low concentration HA （LHA）, indicating a quick response of starch metabolism. However, higher doses of HA also caused excessive aboveground biomass accumulation and inhibited root growth. Accordingly, an earlier carbon starvation emerged by observing evident starch degradation. Relative bulblet weight gradually decreased with increased HA doses and thereby broke the balance between the source and sink. A low HA concentration at 0.2 mg/L performed best in both root and bulblet growth. The number of roots and root length peaked at 14.5 and 5.75 cm respectively. The fresh bulblet weight and diameter reached 468 mg （2.9 times that under the control treatment） and 11.68 mm, respectively. Further, sucrose/starch utilization and conversion were accelerated and carbon famine was delayed as a result with an average relative bulblet weight of 80.09%. To our knowledge, this is the first HA application and mechanism research into starch metabolism in both in vitro and in vivo condition in bulbous crops.