Open Access

ARTICLE

HD-Zip Transcription Factor is Responsible for No-Lobed Leaf in Watermelon (Citrullus lanatus L.)

Shixiang Duan^1,#, Yaomiao Guo^1,#, Yinping Wang¹, Muhammad Jawad Umer², Dongming Liu¹, Sen Yang¹, Huanhuan Niu¹, Shouru Sun¹, Luming Yang¹, Junling Dou^1,*, Huayu Zhu^1,*

1 College of Horticulture, Henan Agricultural University, Zhengzhou, 450002, China
2 Cotton Institute, Chinese Academy of Agricultural Sciences, Anyang, 455000, China

* Corresponding Authors: Junling Dou. Email: ; Huayu Zhu. Email:
# These authors contributed equally to this work

(This article belongs to the Special Issue: Physiological and Molecular Interventions in Improving Abiotic Stress Tolerance in Plants)

Phyton-International Journal of Experimental Botany 2023, 92(5), 1311-1328. https://doi.org/10.32604/phyton.2023.026928

Received 03 October 2022; Accepted 14 November 2022; Issue published 09 March 2023

Abstract

Leaf is a vital organ of plants that plays an essential role in photosynthesis and respiration. As an important agronomic trait in leaf development, leaf shape is classified into lobed, entire (no-lobed), and serrated in most crops. In this study, two-lobed leaf watermelon inbred lines WT2 and WCZ, and a no-lobed leaf watermelon inbred line WT20 were used to create two F₂ populations. Segregation analysis suggested that lobed leaves were dominant over the no-lobed leaves, and it was controlled by a signal gene. A locus on watermelon chromosome 4 controlling watermelon lobed/no-lobed leaves was identified through BSA-seq strategy combined with linkage analysis. The candidate gene was fine-mapped to a 61.5 kb region between 21,224,481 and 21,285,957 bp on watermelon chromosome 4 using two F₂ populations. Four functional genes were annotated in the candidate region, while sequences blast showed that there was a single-base deletion (A/-) only in the exon of Cla018360, which resulted in premature termination of translation in the no-lobed leaf lines. Function prediction showed that Cla018360 encodes an HD-Zip protein that has been reported to regulate the development of leaf shape. The single-base deletion also occurred in the HD-Zip domain. We inferred that the Cla018360 gene is the candidate gene for regulating the development of lobed/no-lobed leaves in watermelon. Gene expression analysis showed that Cla018360 was highly expressed in young leaves. Phylogenetic analysis showed that Cla018360 had a close genetic relationship with AtHB51, which had been reported to regulate the formation of leaf shape in Arabidopsis. Furthermore, transcriptome analysis showed that a total of 333 differentially expressed genes were identified between WT2 and WT20, of which 115 and 218 genes were upregulated and downregulated in no-lobed leaved watermelon WT20. This study not only provides a good entry point for studying leaf development but also provides foundational insights into breeding for special plant architecture in watermelon.

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Supplementary Material

Supplementary Material File

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