Integrated metabolomic and transcriptomic analysis to characterize cutin biosynthesis between low- and high-cutin genotypes of Capsicum chinense Jacq

Authors: NATARAJAN, PURSUSHOTHAMAN - West Virginia State University; AKINMOJU, TOLULOPE - West Virginia State University; NIMMAKAYALA, PADMA - West Virginia State University; LOPEZ-ORTIZ, CARLOS - West Virginia State University; GARCIA-LOZANO, MARLENY - West Virginia State University; THOMPSON, BENJAMIN - West Virginia State University; Stommel, John; REDDY, UMESH - West Virginia State University

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2020
Publication Date: 2/19/2020
Citation: Natarajan, P., Akinmoju, T.A., Nimmakayala, P., Lopez-Ortiz, C., Garcia-Lozano, M., Thompson, B.J., Stommel, J.R., Reddy, U.K. 2020. Integrated metabolomic and transcriptomic analysis to characterize cutin biosynthesis between low- and high-cutin genotypes of Capsicum chinense Jacq. International Journal of Molecular Sciences. Int. J. Mol. Sci. 2020, 21(4). https://doi.org/10.3390/ijms21041397.
DOI: https://doi.org/10.3390/ijms21041397

Interpretive Summary: Waxy substances including cutin on the surface of pepper fruit help to deter infection by pathogens that cause postharvest decay and insect attack and reduce fruit water loss after harvest. Utilizing plants with uniquely glossy and dull fruit surfaces, we determined that cutin was a major determinant of the degree of fruit glossiness. We analyzed fruit cutin composition and found that a compound called dihydroxy hexadecanoic acid was the most abundant. We then evaluated the expression of genes related to cutin biosynthesis and based on increased expression of cutin related genes in high cutin plants, predicted a putative cutin biosynthetic pathway. This knowledge on the molecular mechansisms regulating cutin biosynthesis in pepper will benefit scientists studying pepper fruit quality and be of value in further research to enhance fruit shelf-life and resistance to pathogens and pests.

Technical Abstract: Habanero peppers constantly face biotic and abiotic stresses such as pathogen/pest infections, extreme temperature, drought and UV radiation. In addition, the fruit cutin lipid composition plays an important role in post-harvest water loss rates, which in turn causes shriveling and reduced fruit quality and storage. In this study, we integrated metabolome and transcriptome profiling pertaining to cutin in two habanero genotypes: PI 222448 and PI 257145. The fruits were selected by the waxy or glossy phenotype on their surfaces. Metabolomics analysis showed a significant variation in cutin composition, with about 6-fold higher cutin in PI 257145 than PI 222448. It also revealed that 10,16-dihydroxy hexadecanoic acid is the most abundant monomer in PI 257145. Transcriptomic analysis of high-cutin PI 257145 and low-cutin PI 222448 resulted in the identification of 2703 statistically significant differentially expressed genes, including 1693 genes upregulated and 1010 downregulated in high-cutin PI 257145. Genes and transcription factors such as GDSL lipase, glycerol-3 phosphate acyltransferase 6, long-chain acyltransferase 2, cytochrome P450 86A/77A, SHN1, ANL2 and HDG1 highly contributed to the high cutin content in PI 257145. We predicted a putative cutin biosynthetic pathway for habanero peppers based on deep transcriptome analysis. This is the first study of the transcriptome and metabolome pertaining to cutin in habanero peppers. These analyses improve our knowledge of the molecular mechanisms regulating the accumulation of cutin in habanero pepper fruits. These resources can be built on for developing cultivars with high cutin content that show resistance to biotic and abiotic stresses with superior postharvest appearance.