Metabolic adaptation and fruit quality formation of citrus auto- and allo-tetraploids

Polyploidy is a widespread phenomenon in nature and has been recognized as a major force in the evolutionary course of higher plants.
Novel phenotypes resulting from polyploidy have been widely applied in plant breeding, especially in improving biomass and stress tolerance.
In our citrus breeding program, numerous auto- and allo-tetraploids were produced via biotechnological approaches.
Metabolic novelty and fruit quality formation following genome doubling were explored through comparative metabolomic analysis, which showed that polyploidy conferred distinct metabolic phenotypes but had a relatively limited influence on three autotetraploids of different citrus genotypes.
Moreover, polyploidy endowed autotetraploids with unique root architecture and enhanced salt tolerance by inducing the activation of ethylene biosynthesis.
Allopolyploidization, involving genome doubling and hybridization, can cause larger metabolic variation compared to autopolyploidization.
A comparison of the acetylome from a citrus allotetraploid somatic hybrid and its diploid parents indicated that parental dominance in specific fruit traits, such as fruit acidity and flavonol metabolism, was highly associated with parental lysine acetylation (Kac) level dominance, which is due to Kac-mediated regulation of enzyme activity.
The acetylome reprogramming after polyploidization can be partially explained by the expression pattern of several lysine deacetylases (KDACs). Additionally, the allotetraploid somatic hybrid fruits displayed significantly lower carotenoid content and higher abscisic acid (ABA) content than both parents, which might be attributed to the downregulation of CsNCED2. Collectively, these findings suggest that polyploidization diverts metabolic flux from primary metabolism to secondary metabolism to relieve “genomic stress” and also reveal the important role of acetylome reprogramming and transcriptional regulation in trait evolution during polyploidization.

IV Asian Horticultural Congress – AHC2023

Wen-Wu Guo, Miao Zhang, Xin Song, Feng-Quan Tan, Kai-Dong Xie, Xiao-Meng Wu

citrus, polyploid, fruit quality, stress tolerance, genetic improvement

https://doi.org/10.17660/ActaHortic.2024.1404.1