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Article|16 Jun 2022|OPEN
A natural mutation of the NST1 gene arrests secondary cell wall biosynthesis in the seed coat of a hull-less pumpkin accession
Xiaolong Lyu1 , Lu Shi1 , Meng Zhao1 , Zhangping Li1 , Nanqiao Liao1 , Yiqing Meng1 , Yuyuan Ma1 , Yulan Zhou1 , Qin Xue1 , Zhongyuan Hu1,2 and Jinghua Yang1,2 , Mingfang Zhang,1,2 ,
1Laboratory of Germplasm Innovation and Molecular Breeding, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
2Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agriculture, Hangzhou 310058, China
*Corresponding author. E-mail: mfzhang@zju.edu.cn

Horticulture Research 9,
Article number: uhac136 (2022)
doi: https://doi.org/10.1093/hr/uhac136
Views: 84

Received: 27 Jan 2022
Accepted: 07 Jun 2022
Published online: 16 Jun 2022

Abstract

Hull-less pumpkins (Cucurbita pepo L.) are naturally occurring novel variants known as oilseed or naked-seeded pumpkins, and are characterized by the absence of a normal lignified seed coat. Due to a specialized seed coat structure, these variants serve as a good model for studying seed coat formation and simplify the processing of pumpkin seeds. However, causal genes for this hull-less trait still remain unknown. Here, by bulked segregant analysis and fine mapping, we found that mutation of a single gene, NAC SECONDARY WALL THICKENING PROMOTING FACTOR 1 (NST1), accounts for the hull-less trait. A 14-bp sequence insertion in the CpNST1 gene causes premature termination of CpNST1 translation, leading to lack of secondary cell wall (SCW) biosynthesis in hull-less seed coats. In situ hybridization analysis provided further evidence for the role of CpNST1 in pumpkin seed coat SCW biosynthesis. Interestingly, through secondary cell wall compositional analysis, we found that the main SCW components differed among cell layers in the seed coat. RNA-seq analysis indicated an upstream role of CpNST1 in the SCW biosynthesis network. Collectively, our findings provide mechanistic insight into seed coat SCW biosynthesis, and a target gene for breeders to introduce this hull-less trait for commercial exploitation.