Biology subjects

Yockteng, R.

Publications and source records attributed to Yockteng, R..

3 recordsLinked to original sources

bioRxiv2023

Characterising genome composition and large structural variation in banana varietal groups

BackgroundBananas and plantains (Musa spp.) are one of the most important crops worldwide. The cultivated varieties are vegetatively propagated, and their diversity is essentially fixed over time. Nevertheless, millennia of diversification and selection have led to hundreds of edible varieties. M. acuminata and M. balbisiana respectively provided the A and B subgenomes that mostly constitute these varieties. Here we aimed to characterise chromosomal exchanges and structural variation among lineages to understand shared foundational events and identify sources of allelic diversity in introgressed loci for genetic improvement. MethodsWe identified clonal somatic groups among 188 banana and plantain accessions introduced for cropping in Colombia, using admixture, principal component, and phylogenetic analyses. We established a new alignment-based metric, named Relative Averaged Alignment (RAA), to infer subgenome composition (AA, AAB, etc.). We later used comparisons in read coverage along conserved chromosomal windows between the A, B, and S subgenomes to identify introgressions. ResultsIn our panel, we identify ten varietal groups composed of somatic clones, plus three groups of tetraploid accessions. We demonstrated RAA can be used to infer subgenome composition in the total genome and individual chromosomes. We identified 20 introgressions, several newly reported, among the AAB and ABB varieties. We did not observe B-donor introgression in any AA/AAA varietal groups. We identified variation in length in at least two introgressions, a B-donor introgression in chromosome 7 between the "Maoli" and a "Popoulu" subdivisions, and an S-donor (M. schizocarpa) introgression in chromosome 2 in four varietal groups with different compositions (AAA, AAB, ABB, and AA). ConclusionsThe extensive distribution of introgressions and the variation in the length of some introgressions between varieties support that the emergence of many varieties can be attributed to intricate founding events, which encompassed multiple instances of hybridisation and subsequent residual backcrossing. We also showed the contribution of M. schizocarpa to four cultivated varieties, and proposed subdivision-specific intergenomic recombination in chromosome 7 between subgroups Maoli and Popoulu plantains. Introgressed loci over these 20 introgressions likely provide an extensive resource of allelic diversity to further explore their contribution to disease resistance, climatic adaption, etc. and potential for exploiting in breeding and genome editing.

plant biology↗

bioRxiv2023

Pleistocene dispersion supports a unique native diversity in the Colombian avocado germplasm

Genomic characterization of ex-situ collections optimizes the utilization of genetic resources, identifies redundancies among accessions, captures cryptic variation, establishes reference collections, and ultimately assists pre-breeding and breeding efforts. However, the integration of population genomic analyses is often lacking when studying the biodiversity of crop gene pools. Here, we present modern classification and machine learning approaches to characterize and harness the genebank of an agrobiodiversity hotspot on Persea americana Mill., an iconic American fruit tree crop that has seen an unprecedented expansion worldwide. We selected 144 accessions from the Colombian National genebank and 240 materials from local plantations in the Colombian Northwest Andes. We genotyped them using a strategy based on reduced representation sequencing. We included available sequences of genotypes from known avocado races, Mexican, Guatemalan, and West Indian, to discover SNPs, analyze the population structure and identify possible new genetic groups in Colombian germplasm. We detected a population structure suggestive of a new fourth race in Colombia, with a possible genetic substructure related to geographical origin (Andean and Caribbean). Hybrid determination and ABC modeling suggested rampant inter-race geneflow. They supported the hypothesis of the high mobility of native avocado trees from Central America to Northern South America starting in the Pleistocene. Our study supports that Colombia might be a new diversity center for P. americana. Genotypes of the two newly identified Colombian groups can be used as parents in plant breeding strategies to generate cultivars adapted to specific ecogeographical regions of Colombia.

plant biology↗

bioRxiv2019

{-}{-}Genome wide association study reveals novel candidate genes associated with productivity and disease resistance to Moniliophthora spp. in cacao (Theobroma cacao L.)

Cacao (Theobroma cacao L.), the source of chocolate, is one the most important commodity products for farmers to improve their economic benefits. However, diseases such as frosty pod rot (FPRD) caused by Moniliophthora roreri and witches broom (WBD) caused by Moniliophthora perniciosa, limits the increase in yields. Molecular tools can help to develop more rapidly cacao varieties with disease resistance. In the present study, we sequenced by genotyping-by-sequencing (GBS), 229 cacao accessions to examine their genetic diversity and population structure. From those accessions, 102 have been evaluated for disease resistance and productivity to conduct a genome-wide association study (GWAS) based on 9,003 and 8,131 SNPs recovered by mapping against to the annotated cacao genomes (Criollo and Matina). Three promissory accessions for productivity and 10 accessions showing good tolerance to the evaluated diseases were found in the phenotypic evaluation. The work presented herein provides the first association mapping study in cacao using SNP markers based on GBS data. The GWAS identified two genes associated to productivity and seven to disease resistance. The results enriched the knowledge of the genetic regions associated to important traits in cacao that can have significant implications for conservation and breeding strategies such as marker-assisted selection (MAS).

genetics↗