Identification, Characterization, and Expression Analysis of Carotenoid Biosynthesis Genes and Carotenoid Accumulation in Watercress (Nasturtium officinale R. Br.)

Ramaraj Sathasivam; Sun Ju Bong; Chang Ha Park; Ji Hyun Kim; Jae Kwang Kim; Sang Un Park

doi:10.1021/acsomega.1c04802

Identification, Characterization, and Expression Analysis of Carotenoid Biosynthesis Genes and Carotenoid Accumulation in Watercress (Nasturtium officinale R. Br.)

ACS Omega. 2021 Dec 20;7(1):430-442. doi: 10.1021/acsomega.1c04802. eCollection 2022 Jan 11.

Authors

Ramaraj Sathasivam¹, Sun Ju Bong¹, Chang Ha Park¹, Ji Hyun Kim², Jae Kwang Kim², Sang Un Park^{1

3}

Affiliations

¹ Department of Crop Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea.
² Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea.
³ Department of Smart Agriculture Systems, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea.

Abstract

Watercress (Nasturtium officinale R. Br.) is an important aquatic herb species belonging to the Brassicaceae family. It has various medicinal properties and has been utilized for the treatment of cancer and other diseases; however, currently available genomic information regarding this species is limited. Here, we performed the first comprehensive analysis of the carotenoid biosynthesis pathway (CBP) genes of N. officinale, which were identified from next-generation sequencing data. We identified and characterized 11 putative carotenoid pathway genes; among these, nine full and two partial open reading frames were determined. These genes were closely related to CBP genes of the other higher plants in the phylogenetic tree. Three-dimensional structure analysis and multiple alignments revealed several distinct conserved motifs, including aspartate or glutamate residues, carotene-binding motifs, and dinucleotide-binding motifs. Quantitative reverse transcription-polymerase chain reaction results showed that the CBP was expressed in a tissue-specific manner: expression levels of NoPSY, NoPDS, NoZDS-p, NoCrtISO, NoLCYE, NoCHXE-p, and NoCCD were highest in the flower, whereas NoLCYB, NoCHXB, NoZEP, and NoNCED were highest in the leaves. Stems, roots, and seeds did not show a significant change in the expression compared to the leaves and flowers. High-performance liquid chromatography analysis of the same organs showed the presence of seven distinct carotenoid compounds. The total carotenoid content was highest in the leaves followed by flowers, seeds, stems, and roots. Among the seven individual carotenoids, the levels of six carotenoids (i.e., 13-Z-β-carotene, 9-Z-β-carotene, E-β-carotene, lutein, violaxanthin, and β-cryptoxanthin) were highest in the leaves. The highest content was observed for lutein, followed by E-β-carotene, and 9-Z-β-carotene; these carotenoids were much higher in the leaves compared to the other organs. The results will be useful references for further molecular genetics and functional studies involving this species and other closely related species.