Heterosis and differential gene expression in hybrids and parents in Bombyx mori by digital gene expression profiling.

Hua Wang,Haiying Wang,Yan Fang,Yanghu Sima,Shiqing Xu,Wenjuan Zhu,Lipeng Wang,Haipeng Ji

doi:10.1038/srep08750

Abstract

Heterosis is a concern to all breeders, but the mechanism of heterosis remains unknown. In F1 organisms, genetic material is inherited from the two parents and theoretically, heterosis might be caused by differences in gene expression or modification. Differential gene expression was analyzed in hybrids and parents in Bombyx mori. The results showed that there were significant changes in gene expression in the fat body involving biological regulation, cellular and metabolic processes. Consistent trends in expression patterns covering different hybrid combinations were seen in 74 genes. Moreover, these differential gene expression patterns included overdominance, dominance, and additive effects. By correlating these patterns with economic traits, a potential relationship was found. Differential gene expression was seen in different cross combinations and in different sexes. In addition, a regulatory mechanism involving metabolism and ErbB signaling pathways was also found, suggesting that such a network might also be related to heterosis in Bombyx mori. Together, our data provide a comprehensive overview and useful resource for transcriptional analysis of heterosis of Bombyx mori.

Highlights

Heterosis and differential gene expression in hybrids and parents in Bombyx mori by digital gene expression profiling
B. mori is an excellent model to investigate the mechanism of heterosis for the following reasons: (i) They are fed with fresh mulberry leaves; (ii) the number of eggs produced by B.mori are sufficiently high that a large number of samples can be procured at one time for statistical analysis; (iii) analysis of heterosis covering economic traits of B.mori has been well characterized and there are many mature appraisal systems widely utilized in silkworm breeding
The gene expression patterns that showed the largest differences for cross females, reciprocal cross females and males compared with parents was UM (13.87%, 6.78% and 17.30%, respectively). These differential gene expression patterns were consistent with the dominance hypothesis, which suggests that a harmful recessive allele from a parent would be inhibited by an advantageous dominant allele from another parent

Summary

Introduction

Heterosis and differential gene expression in hybrids and parents in Bombyx mori by digital gene expression profiling. Consistent trends in expression patterns covering different hybrid combinations were seen in 74 genes These differential gene expression patterns included overdominance, dominance, and additive effects. Recent progress has suggested additional mechanisms which may explain heterosis in Arabidopsis and maize, including expression of small RNA (sRNA)[7] and DNA methylation[8] To examine these mechanisms, transcriptional or gene expression profiles have been completed in maize[9], rice[10,11], and pufferfish[12]. Whole-genome transcriptome analyses of many parental and hybrid offspring plants have been completed, and correlations between differential gene expression patterns and traits have been demonstrated[9,14,15,16,17]. We used B. mori to investigate correlations between gene expression patterns and heterosis

Methods

Results

Conclusion