QTL mapping and stability analysis of trichome density in zucchini (Cucurbita pepo L.)

Yunli Wang; Guichao Wang; Dongjuan Lin; Qinfen Luo; Wenlong Xu; Shuping Qu

doi:10.3389/fpls.2023.1232154

QTL mapping and stability analysis of trichome density in zucchini (Cucurbita pepo L.)

Front Plant Sci. 2023 Aug 11:14:1232154. doi: 10.3389/fpls.2023.1232154. eCollection 2023.

Authors

Yunli Wang^{1

2}, Guichao Wang^{1

2}, Dongjuan Lin^{1

2}, Qinfen Luo^{1

2}, Wenlong Xu^{1

2}, Shuping Qu^{1

2}

Affiliations

¹ Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs/Northeast Agricultural University, Harbin, China.
² College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin, China.

Abstract

Trichomes provide an excellent model for studying cell differentiation and proliferation. The aboveground tissues of plants with long dense trichomes (LDTs) can cause skin itching in people working in a zucchini field, in which management, pollination, and fruit harvesting are difficult. In this study, an F₂ population was constructed with the LDT inbred line "16" and the sparse micro trichome (SMT) inbred line "63" for QTL analysis of type I and II trichome density. Two QTLs were identified on chromosomes 3 and 15 using the QTL-seq method. Additionally, 191 InDel markers were developed on 20 chromosomes, a genetic map was constructed for QTL mapping, and three QTLs were identified on chromosomes 3, 6, and 15. Two QTLs, CpTD3.1 and CpTD15.1, were identified in both QTL-seq and genetic map-based QTL analyses, and CpTD15.1 was the major-effect QTL. The stability of CpTD3.1 and CpTD15.1 was confirmed using data from F₂ plants under different environmental conditions. The major-effect QTL CpTD15.1 was located between markers chr15-4991349 and chr15-5766791, with a physical distance of 775.44 kb, and explained 12.71%-29.37% of the phenotypic variation observed in the three environments. CpTD3.1 was located between markers chr3-218350 and chr3-2891236, in a region with a physical distance of 2,672.89 kb, and explained 5.00%-10.64% of the phenotypic variation observed in the three environments. The functional annotations of the genes within the CpTD15.1 region were predicted, and five genes encoding transcription factors regulating trichome development were selected. Cp4.1LG15g04400 encoded zinc finger protein (ZFP) and harbored nonsynonymous SNPs in the conserved ring finger domain between the two parental lines. There were significant differences in Cp4.1LG15g04400 expression between "16" and "63", and a similar pattern was found between germplasm resources of LDT lines and SMT lines. It was presumed that Cp4.1LG15g04400 might regulate trichome density in zucchini. These results lay a foundation for better understanding the density of multicellular nonglandular trichomes and the regulatory mechanism of trichome density in zucchini.

Keywords: Cucurbita pepo; InDel markers; QTL analysis; trichome density; zinc finger protein.

Grants and funding

This work was supported by grants from the National Natural Science Foundation of China (32272723 and 32072590), the National Natural Science Foundation of China (32002051), the Academic Backbone Foundation of Northeast Agricultural University (20XG03), the Postdoctoral Science Foundation of China (2019M661244), the Open Project of Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), and the Ministry of Agriculture and Rural Affairs.