In Arabidopsis hybrids and Hybrid Mimics, up‐regulation of cell wall biogenesis is associated with the increased plant size

Abstract

Hybrid breeding is of economic importance in agriculture for increasing yield, yet the basis of heterosis is not well understood. In Arabidopsis, crosses between different accessions produce hybrids with different levels of heterosis relative to parental phenotypes in biomass. In all hybrids, the advantage of the F1 hybrid in both phenotypic uniformity and yield gain is lost in the heterogeneous F2. F5/F6 Hybrid Mimics generated from a cross between C24 and Landsberg erecta (Ler) ecotypes demonstrated that the large plant phenotype of the F1 hybrids can be stabilized. Hybrid Mimic selection was applied to Wassilewskija (Ws)/Ler and Col/Ler hybrids. The two hybrids show different levels of heterosis. The Col/Ler hybrid generated F7 Hybrid Mimics with rosette diameter and fresh weight equivalent to the F1 hybrid at 30 DAS; F7 Ws/Ler Hybrid Mimics outperformed the F1 hybrid in both the rosette size and biomass. Transcriptome analysis revealed up‐regulation of cell wall biosynthesis, and cell wall expansion genes could be a common pathway in increased size in the Arabidopsis hybrids and Hybrid Mimics. Intercross of two independent Hybrid Mimic lines can further increase the biomass gain. Our results encourage the use of Hybrid Mimics for breeding and for investigating the molecular basis of heterosis.

In Arabidopsis thaliana Heterosis Level Varies among Individuals in an F1 Hybrid Population

“…Expansin (EXP) and Xyloglucan endotransglucosylases/hydrolase (XTH) are known to be involved in loosening cell wall architecture and cell enlargement [37]. Upregulation of XTH genes has been observed in heterotic hybrids and hybrid mimic lines [17,38]. In this study, overexpression of β-expansin 1 (EXPB1) induced increased plant size at 14 DAS, while overexpression of EXPB3 did not change the plant size.…”

Comparative transcriptomic analysis reveals the molecular mechanism underlying seedling biomass heterosis in Brassica napus

“…In poplars, the advantage of leaf size in triploid hybrids is positively correlated with an increase in the expression of genes regulating cell size [ 33 ]. In Arabidopsis , changes related to genes of leaf size during hybrid rosette development have been observed [ 34 ] as well as the upregulated expression of xyloglucan endotransglucosylase/hydrolase-related genes in the three hybrid systems [ 35 ]. However, the factors that drive the upregulation of cell size-related genes in hybrids remain unclear.…”