Journal of Integrative Agriculture ›› 2022, Vol. 21 ›› Issue (3): 725-735.DOI: 10.1016/S2095-3119(20)63502-X

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  • 收稿日期:2020-09-02 接受日期:2020-11-15 出版日期:2022-03-01 发布日期:2020-11-15

Manual thinning increases fruit size and sugar content of Citrus reticulata Blanco and affects hormone synthesis and sugar transporter activity

LIU Cong1, LI De-xiong2, HUANG Xian-biao2, Zhang Fu-qiong2, Xie Zong-zhou1, Zhang Hong-yan1, Liu Ji-hong1   

  1. 1 Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, P.R.China
    2 Dangyang Specialty Products Center, Dangyang 444100, P.R.China
  • Received:2020-09-02 Accepted:2020-11-15 Online:2022-03-01 Published:2020-11-15
  • About author: Correspondence LIU Ji-hong, E-mail: liujihong@mail.hzau.edu.cn
  • Supported by:

    This work was supported by the Hubei Provincial Agriculture Research System, China, the Special Program for Technology Innovation of Hubei Province, China (2020BBA036) and the Hubei Provincial Agricultural Science and Technology Innovation, China.

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摘要：

人工疏果可以显著促进果实膨大，提高果实品质，但是人工疏果对椪柑品质的影响及其机理尚未有系统研究。研究以‘鄂柑一号’椪柑（Citrus reticulata Blanco）为研究对象，分析人工疏果对椪柑果实品质的影响及其机理。结果发现，人工疏果可以促进椪柑果实膨大，提高椪柑果实可溶性固形物含量。基因相对表达量分析表明，人工疏果促进了糖转运因子SUT1，STP1，TMT1在果肉中的表达，促进了果实对糖的吸收。此外，人工疏果促进了生长素和赤霉素合成基因的表达，同时对植物内源激素含量测定表明，疏果前激素水平无显著差异，疏果后内源激素尤其是生长素含量在各组织中显著高于对照组。本研究推测，人工疏果通过影响果实内源激素含量变化引起果实品质的变化。


Abstract: Manual fruit thinning (MFT) in fruit trees has been previously shown to increase fruit size and enhance fruit quality, but the effect of MFT on Ponkan (Citrus reticulata Blanco) and the underlying mechanisms remain poorly understood.  In this study, efforts were made to elucidate how MFT influences the fruit quality of Ponkan.  The results showed that MFT substantially increased fruit size and elevated fruit total soluble solids in comparison with the fruit from the unthinned trees (used as control).  Expression analyses demonstrated that mRNA abundance of three important sugar transporter genes, including CrSUT1, CrSTP1 and CrTMT1, was evidently elevated in the flesh of thinned fruit when compared with those of the control.  In addition, MFT prominently up-regulated the transcript levels of various auxin and gibberellin (GA) biosynthesis and signaling genes, including CrYUC6, CrAUX/IAA, CrGA20ox1 and CrGA3ox1.  Concurrently, the contents of endogenous IAA and GA3, measured at 90 d after fruit thinning, were notably elevated in the fruit from trees with the thinning treatment relative to the control, although no difference was detected in the two groups before the thinning manipulation.  Taken together, these results indicate that manual fruit thinning could greatly improve fruit quality, which may be attributed to promoting fruit expansion due to the increased auxin levels and expediting sugar accumulation through the up-regulation of sugar transporter genes.

Key words: Citrus reticulata Blanco ,  auxin ,  fruit expansion ,  fruit quality ,  gene expression ,  gibberellin ,  sugar content