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Int. J. Mol. Sci. 2019, 20(8), 1890;

Pitaya HpWRKY3 Is Associated with Fruit Sugar Accumulation by Transcriptionally Modulating Sucrose Metabolic Genes HpINV2 and HpSuSy1

State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables/Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China) of Ministry of Agriculture/Engineering Research Center of Southern Horticultural Products Preservation, Ministry of Education, College of Horticulture, South China Agricultural University, Guangzhou 510642, China
School of Food and Pharmaceutical Engineering, Guizhou Engineering Research Center for Fruit Processing, Guiyang University, Guiyang 550003, China
Department of Food Science, Guangdong Food and Drug Vocational College, Guangzhou 510520, China
Authors to whom correspondence should be addressed.
These authors contribute equally to this work.
Received: 12 March 2018 / Revised: 14 April 2019 / Accepted: 15 April 2019 / Published: 17 April 2019
(This article belongs to the Special Issue Transcriptional and Post-transcriptional Gene Regulation in Plants)
PDF [3144 KB, uploaded 17 April 2019]


Sugar level is an important determinant of fruit taste and consumer preferences. However, upstream regulators that control sugar accumulation during fruit maturation are poorly understood. In the present work, we found that glucose is the main sugar in mature pitaya (Hylocereus) fruit, followed by fructose and sucrose. Expression levels of two sucrose-hydrolyzing enzyme genes HpINV2 and HpSuSy1 obviously increased during fruit maturation, which were correlated well with the elevated accumulation of glucose and fructose. A WRKY transcription factor HpWRKY3 was further identified as the putative binding protein of the HpINV2 and HpSuSy1 promoters by yeast one-hybrid and gel mobility shift assays. HpWRKY3 was localized exclusively in the nucleus and possessed trans-activation ability. HpWRKY3 exhibited the similar expression pattern with HpINV2 and HpSuSy1. Finally, transient expression assays in tobacco leaves showed that HpWRKY3 activated the expressions of HpINV2 and HpSuSy1. Taken together, we propose that HpWRKY3 is associated with pitaya fruit sugar accumulation by activating the transcriptions of sucrose metabolic genes. Our findings thus shed light on the transcriptional mechanism that regulates the sugar accumulation during pitaya fruit quality formation. View Full-Text
Keywords: fruit maturation; fruit quality; sucrose-hydrolyzing enzyme genes; transcriptional activation fruit maturation; fruit quality; sucrose-hydrolyzing enzyme genes; transcriptional activation

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Wei, W.; Cheng, M.-N.; Ba, L.-J.; Zeng, R.-X.; Luo, D.-L.; Qin, Y.-H.; Liu, Z.-L.; Kuang, J.-F.; Lu, W.-J.; Chen, J.-Y.; Su, X.-G.; Shan, W. Pitaya HpWRKY3 Is Associated with Fruit Sugar Accumulation by Transcriptionally Modulating Sucrose Metabolic Genes HpINV2 and HpSuSy1. Int. J. Mol. Sci. 2019, 20, 1890.

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