Genetic regulators of alien chromosome transmission in wide hybridization for crop improvement

Overview

This research addresses a critical barrier in crop improvement: the genetic mechanisms that regulate preferential transmission of alien chromosomes during wide hybridization between wild crop relatives and cultivated varieties. Understanding these mechanisms is essential for the successful introgression and utilization of novel genes underlying traits of agronomic importance from wild species into cultivated germplasm. The work focuses on rice, using chromosome segment substitution lines (CSSLs) and monosomic alien addition line-derived introgression lines (MDILs) from Oryza nivara and O. latifolia, with broader applications for alien introgression in other crops.

Technical specifications

Key research findings:

• Molecular marker profiling of 26 CSSLs and 27 MDILs revealed systematic transfer of a common chromosome 6 fragment across all MDILs and more than 75% of CSSLs
• Alien introgressions from chromosome 7 were largely absent except in two CSSLs (NSL16 and NSL17), which exhibited 50% yield reduction compared to recurrent parents
• Combined genotyping and phenotyping data suggest the presence of a positive regulator of chromosome transmission on chromosome 7 and a negative regulator on chromosome 6 from both wild rice species
• The discovery parallels prior findings in wheat, where a genetic 'breaker' induces alien chromosome breakage and an 'inhibitor' suppresses it, with both elements reducing yields by 50%

Future research direction:

• Map, clone, and validate the function of genetic factors regulating systematic chromosome transfer in wide hybrids
• Develop segregating populations using CSSLs with overlapping chromosome 7 introgressions to individually isolate candidate genetic regulators on chromosomes 6 and 7
• Positional cloning of both regulatory genes to enable efficient movement of target traits from exotic to cultivated germplasm

Technology readiness level

This research is at an early-to-mid stage of development. Initial discovery and validation have been completed through molecular marker profiling and phenotypic analysis of existing CSSL and MDIL populations. The next phase requires funding support for developing and genotyping mapping populations to support positional cloning of the identified genetic regulators. The research team is seeking partnership and funding to advance toward gene isolation and functional validation, with results expected to leverage alien introgression research across multiple crop species.