Single nucleotide polymorphisms of the Waxy gene and their relationship with the physicochemical properties of Pueraria lobata (kudzu) starch

Ruiqi Zha, Ying Fan, Yuhao Fu , Chunyan Liu, Haoliang Sun, Jiaxin Wan,  Min Wei, Zhixing Jin, Peng Li, Zhongyan Zhu, Jing Wei, Jun Yin, Jun Zhu

Carbohydrate polymers, Volume368, Issue Pt 2, 25 September 2025（IF=12.9）

Abstract

Pueraria lobata (kudzu) is a vital functional food in East Asia, valued for its high content of puerarin, amylose, and resistant starch (RS). Despite its importance, genetic improvement of kudzu starch is hindered by limited research on key synthesis genes, particularly Waxy (Wx) genes. Understanding natural genetic variation can elucidate differences in starch physicochemical properties among varieties. Here, we investigated two prominent southern China cultivars: Pueraria montana var. lobata (P. lobata) and Pueraria montana var. thomsonii (P. thomsonii). We successfully cloned their Wx1 and Wx2 genes and identified a single nucleotide polymorphism (SNP) in exon 7 of the Wx2 gene as the primary determinant for variations in amylose content and molecular weight between the two varieties. Notably, P. lobata and P. thomsonii exhibit high RS content, reaching 52.03 % and 45.95 %, respectively. However, P. thomsonii starch demonstrates superior eating quality. While both varieties share similar amylopectin chain distributions, P. lobata shows lower branch degrees. The identified variations in the Wx2 gene directly lead to differences in starch physicochemical properties, primarily influencing amylose and resistant starch levels. These findings significantly advance our comprehension of kudzu functional genomics and offer crucial insights for the targeted breeding of starch-enhanced kudzu varieties.