Metabolic diversity in a collection of wild and cultivated Brassica rapa subspecies

Shuning Zheng; Jędrzej Szymański; Nir Shahaf; Sergey Malitsky; Sagit Meir; Xiaowu Wang; Asaph Aharoni; Ilana Rogachev

doi:10.3389/fmolb.2022.953189

Metabolic diversity in a collection of wild and cultivated Brassica rapa subspecies

Front Mol Biosci. 2022 Nov 16:9:953189. doi: 10.3389/fmolb.2022.953189. eCollection 2022.

Authors

Shuning Zheng¹, Jędrzej Szymański^{1

2}, Nir Shahaf¹, Sergey Malitsky¹, Sagit Meir¹, Xiaowu Wang³, Asaph Aharoni¹, Ilana Rogachev¹

Affiliations

¹ Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel.
² Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Seeland, Germany.
³ Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.

Abstract

Brassica rapa (B. rapa) and its subspecies contain many bioactive metabolites that are important for plant defense and human health. This study aimed at investigating the metabolite composition and variation among a large collection of B. rapa genotypes, including subspecies and their accessions. Metabolite profiling of leaves of 102 B. rapa genotypes was performed using ultra-performance liquid chromatography coupled with a photodiode array detector and quadrupole time-of-flight mass spectrometry (UPLC-PDA-QTOF-MS/MS). In total, 346 metabolites belonging to different chemical classes were tentatively identified; 36 out of them were assigned with high confidence using authentic standards and 184 were those reported in B. rapa leaves for the first time. The accumulation and variation of metabolites among genotypes were characterized and compared to their phylogenetic distance. We found 47 metabolites, mostly representing anthocyanins, flavonols, and hydroxycinnamic acid derivatives that displayed a significant correlation to the phylogenetic relatedness and determined four major phylometabolic branches; 1) Chinese cabbage, 2) yellow sarson and rapid cycling, 3) the mizuna-komatsuna-turnip-caitai; and 4) a mixed cluster. These metabolites denote the selective pressure on the metabolic network during B. rapa breeding. We present a unique study that combines metabolite profiling data with phylogenetic analysis in a large collection of B. rapa subspecies. We showed how selective breeding utilizes the biochemical potential of wild B. rapa leading to highly diverse metabolic phenotypes. Our work provides the basis for further studies on B. rapa metabolism and nutritional traits improvement.

Keywords: Brassica rapa; mass spectrometry; metabolite profiling; multivariate data analysis; phylogenetic analysis; selective breeding; specialized metabolism.