Occurrence of triploids in oil palm and their origin.

Abstract

Background and aims Oil palms showing exceptional vigour and dubbed as 'giant palms' were identified in some progeny during breeding. A panel of phenotypical traits were studied to characterize these trees. The hypothesis that gigantism and other anomalies might be linked to polyploidy was investigated. Methods Twenty sib pairs of palms from different crosses, each comprising a giant and a normal oil palm, were studied by flow cytometry with rice 'Nipponbare' as standard reference. In parallel, palms were assessed in the field using 11 phenotypic traits. A principal component analysis (PCA) was conducted to define relationships between these phenotypical traits, and a linear discriminant analysis (LDA) to predict ploidy level and giant classification. Finally, a co-dominant molecular marker study was implemented to highlight the sexual process leading to the formation of 2n gametes. Key results The first group of oil palms presented an oil palm/rice peak ratio of around 4.8 corresponding to diploid oil palms, whereas the second group presented a ratio of around 7, classifying these plants as triploid. The PCA enabled the classification of the plants in three classes: 21 were normal diploid palms; ten were giant diploid palms; while 11 were giant triploid palms. The LDA revealed three predictors for ploidy classification: phyllotaxy, petiole size and circumference of the plant, but surprisingly not height. The molecular study revealed that triploid palms arose from 2n gametes resulting from the second division restitution of meiosis in parents. Conclusions This study confirms and details the process of sexual polyploidization in oil palm. It also identifies three phenotypical traits to assess the ploidy level of the giant oil palms in the field. In practical terms, our results provide a cheap scientific method to identify polyploid palms in the field.

Plant phenotyping relevance

圃場形質とPCA/LDAを組み合わせ、油ヤシの倍数性を低コストで判定する実用的な表現型ベース手法を提示しており、形質測定・分類法が研究の中心的成果に含まれる。

Code and data availability

The paper reports flow cytometry, 11 phenotypic traits, PCA/LDA, and SSR genotyping on oil palm pairs, but no public phenotype dataset, images, author analysis code, or supplementary data deposit is mentioned. The only URLs are the OUP reuse license, a commercial genotyping lab (adnid.fr), the generic ggord R package,油

No evidence-backed public reproduction asset is currently recorded.