Biology subjects

Tieman, D.

Publications and source records attributed to Tieman, D..

3 recordsLinked to original sources

bioRxiv2021

Terpene volatiles mediates the chemical basis of blueberry aroma and consumer acceptability

Among the main features treasured by blueberry consumers, flavor is the most important. Human perception of food flavors can primarily be divided into two main sensory inputs, taste and aroma. Through retronasal olfaction, a group of metabolites called volatile organic compounds (VOCs) emitted from the fruit are able to produce the sensation of aroma, creating the myriad of flavors experienced during our life. In blueberry, breeders have noticed some genotypes with unique floral and sweet flavor notes that, ultimately, enhance human aroma perception. Despite the importance, both the understanding of which chemicals are mediating this variation across phenotypes and the potential impact on consumer preferences remains largely unknown. In this study we dissected the main components underlying blueberry aroma and associated it with consumer predilections by paring metabolomics with sensory analysis. Our contribution in this study is four-fold: (i) first, based on a representative blueberry germplasm cultivated at the University of Florida, we differentiated genotypes with floral and sweet aromatic notes and confirmed that such unique characteristics are preferred by consumers; (ii) at the chemical level, we showed that a group of eight terpene volatiles constitute the primary metabolic group associated with aroma sensation; (iii) we demonstrated that aromatic genotypes can be classified using information from a group of a few key volatiles; and finally, (iv) we combined pedigree and metabolomic information in a single predictive framework and showed the importance of metabolomic data for flavor-assisted selection. For the blueberry community, our findings open new venues to explore flavor. Broadly, we present an emerging view about flavor and provide a detailed blueprint of how this target could be addressed in fruits and vegetables.

genetics↗

bioRxiv2021

The evolutionary dynamics of genetic mutational load throughout tomato domestication history

Understanding the evolution of deleterious mutations through domestication has fascinated evolutionary biologists and breeders alike. Some domesticated organisms have been reported to accumulate deleterious mutations, i.e. radical amino acid changes, through their domestication history ("cost of domestication"). However, more recent evidence paints a more complex picture of this phenomenon in different domesticated organisms. In this study, we used genomic sequences of 253 tomato accessions to investigate the evolution of deleterious mutations and genomic structural variants (SVs) through tomato domestication history. Specifically, we used phylogeny-based methods to identify deleterious mutations in the cultivated tomato as well as its closely related semi-wild and wild populations. We also explored a potential correlation between deleterious mutations and SVs. To create a functional link between deleterious alleles and phenotypes of interest for tomato breeding, we also conducted Genome-wide Association Studies (GWAS) on several fruit volatiles. Our results implicate a downward trend, throughout tomato domestication history, in diversity of most alleles, regardless of their functional impact. This suggests that demographic factors, such as bottleneck events and inbreeding, have reduced overall genetic diversity, leading to lower deleterious load and SVs as well as loss of some beneficial alleles during tomato domestication. We also detected an increase in proportions of nonsynonymous and deleterious alleles (relative to synonymous and neutral nonsynonymous alleles, respectively) during the initial stage of tomato domestication in Ecuador, although the final stage of tomato domestication in Mexico did not seem to involve such an increase. However, deleterious alleles in cultivated tomato seem to be more frequent than expected by neutral theory of molecular evolution. Additionally, for all tomato populations, we found a higher proportion of deleterious mutations in genomic regions impacted by SVs. Our analyses also revealed frequent deleterious alleles in several well-studied tomato genes, probably involved in response to biotic and abiotic stress as well as fruit development and flavor regulation. Also, through genome-wide association studies (GWAS), we discovered deleterious alleles associated with two volatiles: isobutyl acetate, which is important for tomato fruit flavor, and methyl salicylate, involved in disease resistance and regulating flowering time. To provide a practical guide for breeding experiments, we created TomDel, a public searchable database of 21,162 deleterious alleles identified in this study (https://github.com/hrazif/TomDel-0.1)

genomics↗

bioRxiv2020

Metabolomic Selection for Enhanced Fruit Flavor

Although they are staple foods in cuisines globally, commercial fruit varieties have become progressively less flavorful over time. Due to the cost and difficulty associated with flavor phenotyping, many breeding programs have long been challenged in selecting for this complex trait. To address this issue, we leveraged targeted metabolomics of diverse tomato and blueberry accessions and their corresponding consumer panel ratings to create statistical and machine learning models that can predict sensory perceptions of fruit flavor. Using these models, a breeding program can assess flavor ratings for a large number of varieties, previously limited by the low-throughput and high cost of consumer sensory panels. The ability to predict consumer ratings of liking, sweet, sour, umami, and flavor intensity was evaluated by a 10-fold cross-validation and the accuracies of 18 different models are assessed. The best performing models were used to infer the flavor compounds (sugars, acids, and volatiles) that contribute most to each flavor attribute. The prediction accuracies were high for most attributes in both blueberries and tomatoes. We expect that these models will enable an earlier incorporation of flavor as breeding targets and encourage selection and release of more flavorful fruit varieties.

plant biology↗