East Timor as an important source of cashew (Anacardium occidentale L.) genetic diversity

Lara Guterres; João Barnabé; André Barros; Alberto Bento Charrua; Maria Cristina Duarte; Maria M Romeiras; Filipa Monteiro

doi:10.7717/peerj.14894

East Timor as an important source of cashew (Anacardium occidentale L.) genetic diversity

PeerJ. 2023 Apr 24:11:e14894. doi: 10.7717/peerj.14894. eCollection 2023.

Authors

Lara Guterres^{1

2

3}, João Barnabé^{2

4}, André Barros⁵, Alberto Bento Charrua^{1

2

6}, Maria Cristina Duarte⁴, Maria M Romeiras^{2

4}, Filipa Monteiro^{2

4}

Affiliations

¹ Nova School of Business and Economics, Campus de Carcavelos, Universidade Nova de Lisboa, Cascais, Portugal.
² LEAF-Linking Landscape, Environment, Agriculture and Food Research Center, Associated Laboratory TERRA, School of Agriculture (ISA), University of Lisbon, Lisbon, Portugal.
³ Universidade Nacional Timor Lorosa'e (UNTL), Díli, East-Timor.
⁴ cE3c-Centre for Ecology, Evolution and Environmental Changes & CHANGE-Global Change and Sustainability Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal.
⁵ Innate Immunity and Inflammation Laboratory, Instituto Gulbenkian de Ciência (IGC), Oeiras, Portugal.
⁶ Department of Earth Sciences and Environment, Faculty of Science and Technology, Licungo University, Beira, Mozambique.

Abstract

Background: Cashew (Anacardium occidentale L.) is a crop currently grown in several tropical countries because of the economic importance of cashew nuts. Despite its enormous economic worth, limited research has been conducted on the molecular diversity of cashew genetic resources. In this study, a wide comprehensive assessment of the genetic diversity of cashew trees in East Timor was performed using microsatellites (SSRs) to evaluate intraspecific diversity and population structuring.

Methods: A total of 207 individual cashew trees, including trees from East Timor (11), and outgroup populations from Indonesia (one) and Mozambique (two), were analyzed with 16 cashew-specific SSRs. A comprehensive sampling of cashew trees within East Timor was performed, covering the distribution of cashew orchards in the country. Genetic diversity indices were calculated, and population structuring was determined using three different approaches: genetic distances (UPGMA and NJ), AMOVA, and individual-based clustering methods through Bayesian (STRUCTURE) and multivariate (DAPC) analyses.

Results: The population structuring analysis revealed that the genetic diversity of cashew populations in East Timor was higher in this study than previously reported for cashew trees. A higher allelic richness was found within cashew populations in East Timor compared with the outgroup populations (Mozambique and Indonesia), reinforced by the presence of private alleles. Moreover, our study showed that cashew populations in East Timor are grouped into two dissimilar genetic groups, which may suggest multiple cashew introductions over time. These new cashew genetic resources could be explored for future crop improvement.

Conclusions: Crop diversity underpins the productivity, resilience, and adaptive capacity of agriculture. Therefore, this study provides useful information regarding genetic diversity and population structure that can be harnessed to improve cashew production in East Timor. This data is also important to creating a country-specific genetic cashew signature to increase cashew market value.

Keywords: Diversity hotspots; Genetic diversity; Population structuring; SSRs; Southeast Asia.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anacardium* / chemistry
Bayes Theorem
Genetic Variation / genetics
Indonesia
Timor-Leste

Associated data

figshare/10.6084/m9.figshare.19119041.v3

Grants and funding

This research was funded by FCT–Fundação para a Ciência e a Tecnologia, I.P. under the project GenoCash (PTDC/ASP-AGR/0760/2020). Fellowships were funded by Portuguese National Funds through FCT, Portugal: SFRH/BD/135358/2017 to Lara Guterres and SFRH/BD/135360/2017 to Alberto Bento Charrua, and research units: UID/AGR/04129/2020 (LEAF); UID/BIA/00329/2020 (cE3c). The fellowship for João Barnabé was funded by FAO/UN (TCP/GBS/3801). The APC was funded by Fundacão para a Ciência e Tecnologia (FCT) under the GenoCash project (PTDC/ASP-AGR/0760/2020). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.