Biology subjects

Braatz de Andrade, L. R.

Publications and source records attributed to Braatz de Andrade, L. R..

2 recordsLinked to original sources

bioRxiv2020

Comprehensive genotyping of Brazilian Cassava (Manihot esculenta Crantz) Germplasm Bank: insights into diversification and domestication

Cassava (Manihot esculenta Crantz) is a major staple root crop of the tropics, originating from the Amazonas region. In this study, 3,354 cassava landraces and modern breeding lines from the Embrapa Cassava Germplasm Bank (CGB) were characterized. All individuals were subjected to genotyping-by-sequencing (GBS), identifying 27,045 Single Nucleotide Polymorphisms (SNPs). Identity-by-state and population structure analyses revealed a unique set of 1,536 individuals and 10 distinct genetic groups with heterogeneous linkage disequilibrium (LD). On this basis, 1,300 to 4,700 SNP markers were selected for large quantitative trait loci (QTL) detection. Identified genetic groups were further characterized for population genetics parameters including minor allele frequency (MAF), observed heterozygosity (Ho), effective population size estimate [Formula] and polymorphism information content (PIC). Selection footprints and introgressions of M. glaziovii were detected. Spatial population structure analysis revealed five ancestral populations related to distinct Brazilian ecoregions. Estimation of historical relationships among identified populations suggest earliest population split from Amazonas to Atlantic forest and Caatinga eco-regions and active gene flows. This study provides a thorough genetic characterization of ex situ germplasm resources from cassava center of origin, South America, with results shedding light on Brazilian cassava characteristics and its biogeographical landscape. These Findings support and facilitate the use of genetic resources in modern breeding programs including implementation of association mapping and genomic selection strategies. Key messageBrazilian cassava diversity was characterized through population genetics and clustering approaches, highlighting contrasted genetic groups, and spatial genetic differentiation.

plant biology↗

bioRxiv2020

Genetic architecture and gene mapping of cyanide in cassava (Manihot esculenta Crantz.)

Cassava is a root crop originating from South America and a major staple crop in the Tropics, including marginal environments. In this study, we focused on South American and African cassava germplasm and investigated the genetic architecture of Hydrogen Cyanide (HCN), a major component of tuber quality. HCN is a plant defense component against herbivory but also toxic for human consumption. We genotyped 3,354 landraces and modern breeding lines originating from 26 Brazilian states and 1,389 individuals were phenotypically characterized across multi-year trials for HCN. All plant material was subjected to high density genotyping using Genotyping-by-sequencing (GBS). We performed genome wide association mapping (GWAS) to characterize the genetic architecture and gene mapping of HCN. Field experiment revealed strong broad and narrow-sense trait heritability (0.82 and 0.41 respectively). Two major loci were identified, encoding for an ATPase and a MATE protein and contributing up to 7% and 30% of the cyanide concentration in roots, respectively. We developed diagnostic markers for breeding applications, validated trait architecture consistency in African germplasm and investigated further evidence for domestication of sweet and bitter cassava. Fine genomic loci characterization indicate; (i) a major role played by vacuolar transporter in regulating HCN content, (ii) co-domestication of sweet and bitter cassava major alleles to be geographical zone dependant, and (ii) major loci allele for high cyanide cassava in Manihot esculenta Crantz seems to originate from its ancestor, M. esculenta ssp. flabellifolia. Taken together these findings expand insights on cyanide in cassava and its glycosylated derivatives in plants. One-sentence summaryIdentification of an intracellular transporter gene and its allelic variation allow to point out cultivars with up to 30 percent decrease in cassava root cyanide content, toxic for human consumption.

genetics↗