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ORIGINAL RESEARCH article

Front. Plant Sci.
Sec. Crop and Product Physiology
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1544054
This article is part of the Research Topic Plant Responses to Environmental Change View all 4 articles

Low light reduces saffron corm yield by inhibiting starch synthesis

Provisionally accepted
Weijing Yang Weijing Yang 1Xin Li Xin Li 1*Fei Chang Fei Chang 1*Xue Qiu Xue Qiu 2*Xulong Huang Xulong Huang 1*Zhan Feng Zhan Feng 1Jie Yan Jie Yan 1Qinghua Wu Qinghua Wu 1Feiyan Wen Feiyan Wen 1*Jin Pei Jin Pei 1*Tao Zhou Tao Zhou 1*
  • 1 Chengdu University of Traditional Chinese Medicine, Chengdu, China
  • 2 Zigong Hospital of Traditional Chinese Medicine, Zigong, Sichuan Province, China

The final, formatted version of the article will be published soon.

    The mechanisms by which low light modulates source-sink dynamics, affecting starch synthesis and formation of underground storage organs in geophyte, remain unclear. In this study, a two-year field experiment was conducted under natural light (NL) and low light (LL, 50% of NL intensity) conditions. LL resulted in a 23.66% and 21.23% reduction in corm yield in 2023 and 2024, respectively. Saffron plants under LL had larger, longer leaves with a higher proportion of dry weight (DW) compared to those under NL. Despite the marked inhibition of photosynthetic capacity, initial DW, sucrose and glucose concentrations in leaves were comparable to those under NL.Carbohydrate analysis revealed that starch concentration in the mother corms under LL decreased by 18.00% relative to NL, while sucrose and glucose concentrations increased by 28.44% and 68.44%, respectively. At the corm expansion stage, sucrose concentration in leaves and daughter corms under LL conditions was 17.32% and 54.08% higher than under NL, but glucose and starch concentrations in daughter corms were 22.08% and 10.22% lower, respectively. Additionally, the activity of invertase (INV), sucrose synthase in the decomposition direction (SUS) and ADPglucose pyrophosphorylase (AGPase) in daughter corms were reduced under LL. LL also affected phytohormones concentrations, with increased levels of indole-3-acetic acid (IAA) and gibberellin (GA1) in LL leaves and daughter corms, and decreased abscisic acid (ABA) levels. Transcriptome and quantitative PCR analyses showed that LL upregulated the expression of genes involved in glycolysis and the tricarboxylic acid cycle in leaves, while downregulating CsSUS, CsINV1, CsAGPS1, CsZEP, and CsNCED, which are key to sucrose hydrolysis, starch synthesis, and ABA biosynthesis. Exogenous GA3 application further inhibited SUS, INV and AGPase activities in daughter corms, indicating that high GA concentrations impair carbohydrate metabolism in these organs. In conclusion, LL decreases saffron corm yield by promoting the allocation of reserves from mother corms to leaves at the seedling stage. By the period of the daughter corms enlargement, elevated GA1 and IAA levels and reduced ABA concentration promote leaf growth while inhibiting carbohydrate metabolism in daughter corms, thereby reducing sucrose transport from leaves to daughter corms and suppressing corm yield formation.

    Keywords: saffron, Low light, Corm yield, Sucrose, Starch, source-sink relationship

    Received: 12 Dec 2024; Accepted: 13 Jan 2025.

    Copyright: © 2025 Yang, Li, Chang, Qiu, Huang, Feng, Yan, Wu, Wen, Pei and Zhou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Xin Li, Chengdu University of Traditional Chinese Medicine, Chengdu, China
    Fei Chang, Chengdu University of Traditional Chinese Medicine, Chengdu, China
    Xue Qiu, Zigong Hospital of Traditional Chinese Medicine, Zigong, Sichuan Province, China
    Xulong Huang, Chengdu University of Traditional Chinese Medicine, Chengdu, China
    Feiyan Wen, Chengdu University of Traditional Chinese Medicine, Chengdu, China
    Jin Pei, Chengdu University of Traditional Chinese Medicine, Chengdu, China
    Tao Zhou, Chengdu University of Traditional Chinese Medicine, Chengdu, China

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