Becerra Lopez-Lavalle, L. A.

bioRxiv2023

Carotenoid composition and sequestration in cassava (Manihot esculentum Crantz) root

Cassava (Manihot esculentum Crantz) is a staple food source for many developing countries. Its edible roots are high in starch but lack micronutrients such as {beta}-carotene. In the present study, analysis of pedigree breeding populations has led to the identification of cassava accessions with enhanced {beta}-carotene contents up to 40 g/g DW. This represents 0.2% of the Recommended Daily Allowance (RDA) for vitamin A. The {beta}-branch of the carotenoid pathway predominates in cassava roots, with dominant levels of {beta}-carotene followed by other minor epoxides of {beta}-ring derived carotenoids. Metabolomic analysis revealed that steady state levels of intermediary metabolism were not altered by the formation of carotenoids, similar to starch and carbohydrate levels. Apocarotenoids appeared to be independent of their carotenoid precursors. Lipidomic analysis provided evidence of a significant positive correlation between carotenoid and lipid content, in particular plastid specific galactolipids. Proteomic analysis of isolated amyloplasts revealed an abundance of carbohydrate/starch biosynthetic associated proteins (e.g. glucose-1-phosphate adenylyltransferase). No carotenoid related proteins were detected even in the highest carotenoid containing lines. Carotenoids were associated with fractions typically annotated as plastoglobuli and plastid membranes (particularly the envelope). Proteomic analysis confirmed these structures apart from plastoglobuli, thus potentially amyloplast structures may not contain classical plastoglobuli structures. HighlightCassava genotypes with enhanced provitamin A content ({beta}-carotene) reveals interconnectivity between the carotenoid pathway, starch and lipid biosynthesis.

plant biology↗

bioRxiv2022

Integrated genetic and metabolic characterisation of diverse Latin American cassava (Manihot esculenta Crantz) germplasm; implications for future breeding strategies

Cassava is an important staple crop for food security in Africa and South America. The present study describes an integrated genomic and metabolomic approach to the characterisation of Latin American cassava germplasm. Classification based on genotyping and the leaf metabolome correlates, the key finding being the adaption to specific eco-geographical environments. In contrast the root metabolome does not relate to the genotypic clustering, suggesting different spatial regulation of this tissues metabolome. The data has been used to generate pan-metabolomes for specific tissues and the inclusion of phenotypic data has enabled the identification of metabolic sectors underlying traits of interest. For example, tolerance to whiteflies was not linked to cyanide content but to cell wall related phenylpropanoids or apocarotenoids. Collectively, these data advance the communities resources and provides a valuable insight into new parental breeding materials with traits of interest directly related to combating food security. Significance statementCassava is a staple crop in developing countries of sub-tropical regions. Traditionally, cassava has been considered as a subsistence crop. However recently it has become a sustainable solution to fulfil both hunger and malnutrition needs, and drive economic development. Varietal improvement via classic breeding has successfully delivered products into the Asian market by including/exchanging germplasm from original Latin American collections. Conversely, modest progress has been achieved in Sub-Saharan countries since genetic resources are biased towards exploitation of local landraces and uncharacterised parental material. The present work explores the genetic and metabolic diversity of Latin American cassavas genebank, one of the largest and most complete worldwide. These data provide a robust characterisation of valuable germplasm that can be exploited in breeding programmes.

plant biology↗