JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2024, Vol. 48 ›› Issue (1): 106-114.doi: 10.12302/j.issn.1000-2006.202201008

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Changes of non-structured carbohydrate and starch metabolizing enzyme in bulbs of Lycoris radiata within the annual growth cycle

WEI Xuying1(), ZHANG Yao2, MA Meixia2, JIANG Xueru2, CHEN Huiting2, WU Jing2, YANG Yu2, CAI Junhuo2,*()   

  1. 1. College of Art, Jiangxi Finance and Economics University, Nanchang 330032, China
    2. College of Landscape and Art, Jiangxi Agricultural University, Nanchang 330045, China
  • Received:2022-01-07 Revised:2022-07-04 Online:2024-01-30 Published:2024-01-24
  • Contact: CAI Junhuo E-mail:Weixuyin74@163.com;Cjhuo7692@163.com

Abstract:

【Objective】The study investigated inherent relationship between the unique growth rhythm of Lycoris spp. and changes in non-structural carbohydrates (NSC) and related metabolic enzyme activities. The aim was to provide a research basis for studies of the intrinsic physiological mechanism of L. spp. unique flowering habits and summer leaf dormancy.【Method】In 4-year-old clonal bulbs of L. radiata, the contents of six NSC and nine starch metabolism activities were determined by spectrophotometric and micrometric methods at six growth stages, including leafing-out period, rapid leaf extension period, leaf maturity period, leaf withering period, dormancy period and flowering period.【Result】The NSC content in bulbs at different developmental stages was significantly different. Total NSC, soluble sugar, fructose, and reductive sugar content were the highest in the leaf maturity period. Starch and sucrose contents were the highest in the leaf withering period. The peak starch accumulation lagged behind that of soluble sugars. Significant differences were evident in the activities of nine metabolic enzymes in bulbs at different developmental stages (P < 0.01). During the same period, the activity of ADP-glucose pyrophorylase (AGP) was significantly higher than those of the other eight enzymes. The activities of β-amylase (β-AL) and starch branching enzyme (SBE) were always higher than α-amylase (α-AL) and starch debranching enzyme(DBE), and the activities of soluble starch synthase (SSS) and sucrose phosphate synthase (SPS) were respectively higher than that of granule-bound starch synthase (GBSS) and sucrose synthase (SuS), which corresponded with the significantly higher fructose content in bulbs in different periods. Sucrose and starch contents were negatively correlated with SBE activity and positively correlated with GBSS activity. The opposite correlations were observed for fructose and maltose. In addition, sucrose content was also negatively correlated with the activity of β-AL.【Conclusion】The change of NSC content in bulbs was positively correlated with the vigorous state of leaf growth. Starch accumulation in bulbs was mainly positively regulated by AGP and SPS and negatively regulated by SSS, SBE and DBE. The accumulation of sucrose in bulbs is mainly from amylolysis, rather than translocation of photosynthetic organs. In addition, the fructose content of bulbs was significantly higher than the sucrose content during the annual growth cycle, which may be related to the unique biological characteristics of L. radiata.

Key words: Lycoris radiata, growth and development, dormancy, bulb physiology, non-structural curbohydrates (NSC), sugar metabolism

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