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

Hasan Mehraj,Naomi Miyaji,Motoki Shimizu,Ayasha Akter,Elizabeth S Dennis,Takahiro Kawanabe,Ryo Fujimoto

doi:10.3390/plants9040414

Abstract

Heterosis or hybrid vigour is a phenomenon in which hybrid progeny exhibit superior yield and biomass to parental lines and has been used to breed F1 hybrid cultivars in many crops. A similar level of heterosis in all F1 individuals is expected as they are genetically identical. However, we found variation in rosette size in individual F1 plants from a cross between C24 and Columbia-0 accessions of Arabidopsis thaliana. Big-sized F1 plants had 26.1% larger leaf area in the first and second leaves than medium-sized F1 plants at 14 days after sowing in spite of the identical genetic background. We identified differentially expressed genes between big- and medium-sized F1 plants by microarray; genes involved in the category of stress response were overrepresented. We made transgenic plants overexpressing 21 genes, which were differentially expressed between the two size classes, and some lines had increased plant size at 14 or 21 days after sowing but not at all time points during development. Change of expression levels in stress-responsive genes among individual F1 plants could generate the variation in plant size of individual F1 plants in A. thaliana.

Highlights

Heterosis or hybrid vigour is the superior performance of F1 plants relative to their inbred parental lines
From our previous data [14], we found that the variation of rosette diameter of F1 hybrid between C24 and Col was larger than that of parental lines (Figure S1)
To examine whether the larger shoot size in F1 plants is due to larger seed size, we examined the relationship between shoot and seed sizes

Summary

Introduction

Heterosis or hybrid vigour is the superior performance of F1 (heterozygous) plants relative to their inbred (homozygous) parental lines. In the process of plant breeding, the phenomenon of heterosis has been exploited in various crops and vegetables because of its effect on yield or stress tolerance [1]. The dominance model explains that heterosis is due to the complementation of deleterious recessive alleles by favourable dominant alleles at multiple loci. The overdominance model argues that the heterozygous state leads to superior performance of hybrids to either homozygous condition. The epistasis model is that interaction of favourable alleles at different loci results in heterosis. Epigenetic modifications are considered to contribute to heterosis; interactions between parental epigenetic states in the two sets of chromosomes in hybrids play a role in heterosis [5,7,8]

Methods

Results

Conclusion