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Functional analysis of the sweetpotato β-Amylase IbBAM48829

ZHANG Shun-Jie1,2,3,4,WU Wei-Tai1,RAN Xi-Yue1,2,3,4,ZHAO Zi-Han1,2,3,4,HAN Yong-Hui1,2,3,4,WU Zheng-Dan1,5,*,ZHANG Kai1,*   

  1. 1 College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; 2 Chongqing Key Laboratory of Biology and Genetic Breeding for Tuber and Root Crops, Chongqing 400715, China; 3 Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing 400715, China; 4 Chongqing Beibei Germplasm Bank of Tuber and Root Crops, Chongqing 400715, China; 5 College of Agriculture, Guangxi University / National Demonstration Center for Experimental Plant Science Education, Nanning 530004, Guangxi, China

  • Received:2025-02-27 Revised:2025-08-14 Accepted:2025-08-14 Published:2025-08-26
  • Supported by:
    This study was supported by the Technology Innovation and Application Development Key Project of Chongqing (cstc2021jscx-gksbX0022), the Guangxi Natural Science Foundation Project (2023GXNSFBA026297), the Special Fund for Chongqing Beibei Germplasm Bank of Tuber and Root Crops (ZWZZ2020005), and the Special Fund for the Innovation Team of Tuber and Root Crops Industry Technology System in Chongqing.

Abstract:

β-Amylase in the storage roots of sweetpotato (Ipomoea batatas (L.) Lam.) catalyzes the hydrolysis of starch into sugars, influencing dry matter content, sweetness, texture, and ultimately, commercial value. Identifying key β-amylase genes and elucidating their functions is essential for improving the quality and palatability of sweetpotato. In this study, we focused on the β-amylase candidate gene IbBAM48829, previously identified through transcriptome analysis based on its differential expression during storage root development. The expression pattern of IbBAM48829 across various sweetpotato tissues was analyzed by RT-qPCR. To investigate its subcellular localization, the pCAMBIA1300-IbBAM48829-GFP expression vector was constructed and transiently expressed in Nicotiana benthamiana leaves. In addition, the pEarleyGate101-IbBAM48829 overexpression vector was generated using Gateway cloning and introduced into Arabidopsis thaliana Col-0 plants via the floral dip method for heterologous expression and functional analysis. The results showed that IbBAM48829 was expressed at lower levels in storage roots but at higher levels in petioles and leaves. Subcellular localization analysis suggested that the IbBAM48829 protein may localize to both the cytoplasm and chloroplasts. Transgenic Arabidopsis lines overexpressing IbBAM48829 displayed no significant differences in growth or flowering phenotypes compared to wild-type plants. However, these lines exhibited significantly increased starch and soluble sugar contents in the leaves, along with a higher thousand-seed weight, while starch content in the root tips remained unchanged. These findings suggest that IbBAM48829 may play a critical role in leaf starch metabolism, potentially accelerating starch degradation and generating osmotically active metabolites that promote stomatal opening and enhance the accumulation of photosynthetic products.

Key words: sweetpotato, β-amylase, starch, heterologous expression, functional analysis

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