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Background <p>The Philippines supplies approximately 86% of the global demand for abaca (<i>Musa textilis</i> Née) fiber. To improve its resistance against pathogens, a backcross (BC<sub>2</sub>) hybrid named Dioscoro 1, was developed by crossing Abuab, an abaca variety with high fiber quality, to Pacol, a wild banana (<i>Musa balbisiana</i> Colla) variety with resistance against bunchy top virus (ABTV). </p> Results <p>Leaf samples from the parental lines (Abuab and Pacol) and their BC<sub>2</sub> were sequenced using RNA-seq to assess expression heterosis, regulatory differences, and their association. Analysis of expression heterosis showed that a large number of genes exhibited non-additive (dominance and transgressive) mode of inheritance, accounting for 83.2% of the total heterotic genes. Overdominant and high-parent Abuab dominant genes in the BC<sub>2</sub> were identified including genes encoding for cellulose synthases. Results indicated that the combined trans and cis + trans (synergistic) regulatory differences largely explain the cumulative effects of evolutionary divergence between the parents and the repeated backcrossing–selection procedures. Genes exhibiting compensatory interaction are significantly enriched under the transgressive mode of inheritance, contributing mostly to the heterotic effect in the backcross under directional selection. Genes belonging to a specific gene action cluster closely in a 3D space, suggesting that modes of expression inheritance follow mathematical patterns. Further statistical analysis reveals that regulatory differences strongly influence expression heterosis. In our concurrent work, the BC<sub>2</sub> demonstrated high-parent Abuab dominance on two important phenotypic traits – fiber length and tensile strength. </p> Conclusion <p>Here, the phenotypic and expression heteroses are inherent even in backcrosses owing to the presence of the two alleles in the Dioscoro 1 genome, albeit in uneven proportions (87.5% Abuab- and 12.5% Pacol-specific alleles for BC<sub>2</sub>). These information provide insights into the genetic mechanisms underlying the heterotic performance of BC<sub>2</sub> and offering valuable directions for abaca breeding. </p>

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Expression heterosis in the abaca (Musa textilis Née) BC2 hybrid, Dioscoro 1

  • 期刊论文

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  • 发表日期：

    2026年1月9日

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  • Nelzo C. Ereful,
  • Roneil Christian S. Alonday,
  • Antonio G. Lalusin

摘要

Background

The Philippines supplies approximately 86% of the global demand for abaca (Musa textilis Née) fiber. To improve its resistance against pathogens, a backcross (BC2) hybrid named Dioscoro 1, was developed by crossing Abuab, an abaca variety with high fiber quality, to Pacol, a wild banana (Musa balbisiana Colla) variety with resistance against bunchy top virus (ABTV).

Results

Leaf samples from the parental lines (Abuab and Pacol) and their BC2 were sequenced using RNA-seq to assess expression heterosis, regulatory differences, and their association. Analysis of expression heterosis showed that a large number of genes exhibited non-additive (dominance and transgressive) mode of inheritance, accounting for 83.2% of the total heterotic genes. Overdominant and high-parent Abuab dominant genes in the BC2 were identified including genes encoding for cellulose synthases. Results indicated that the combined trans and cis + trans (synergistic) regulatory differences largely explain the cumulative effects of evolutionary divergence between the parents and the repeated backcrossing–selection procedures. Genes exhibiting compensatory interaction are significantly enriched under the transgressive mode of inheritance, contributing mostly to the heterotic effect in the backcross under directional selection. Genes belonging to a specific gene action cluster closely in a 3D space, suggesting that modes of expression inheritance follow mathematical patterns. Further statistical analysis reveals that regulatory differences strongly influence expression heterosis. In our concurrent work, the BC2 demonstrated high-parent Abuab dominance on two important phenotypic traits – fiber length and tensile strength.

Conclusion

Here, the phenotypic and expression heteroses are inherent even in backcrosses owing to the presence of the two alleles in the Dioscoro 1 genome, albeit in uneven proportions (87.5% Abuab- and 12.5% Pacol-specific alleles for BC2). These information provide insights into the genetic mechanisms underlying the heterotic performance of BC2 and offering valuable directions for abaca breeding.