# Synergizing breeding strategies via combining speed breeding, phenotypic selection, and marker-assisted backcrossing for the introgression of Glu-B1i in wheat

## TL;DR

This paper introduces a new wheat breeding strategy that combines speed breeding and marker-assisted techniques to significantly reduce development time and improve traits like protein content.

## Contribution

A novel synergized breeding strategy (SBS) is demonstrated, integrating speed breeding and marker-assisted backcrossing for efficient trait introgression in wheat.

## Key findings

- The SBS approach reduced the time to develop a BC2 NIL by 53% compared to traditional methods.
- The new wheat line Milyang56 showed improved protein content and loaf volume due to the Glu-B1i allele introgression.
- The SBS model achieved a 91.5% recurrent genome recovery, demonstrating its efficiency and flexibility for breeders.

## Abstract

Wheat is a major food crop that plays a crucial role in the human diet. Various breeding technologies have been developed and refined to meet the increasing global wheat demand. Several studies have suggested breeding strategies that combine generation acceleration systems and molecular breeding methods to maximize breeding efficiency. However, real-world examples demonstrating the effective utilization of these strategies in breeding programs are lacking. In this study, we designed and demonstrated a synergized breeding strategy (SBS) that combines rapid and efficient breeding techniques, including speed breeding, speed vernalization, phenotypic selection, backcrossing, and marker-assisted selection. These breeding techniques were tailored to the specific characteristics of the breeding materials and objectives. Using the SBS approach, from artificial crossing to the initial observed yield trial under field conditions only took 3.5 years, resulting in a 53% reduction in the time required to develop a BC2 near-isogenic line (NIL) and achieving a higher recurrent genome recovery of 91.5% compared to traditional field conditions. We developed a new wheat NIL derived from cv. Jokyoung, a leading cultivar in Korea. Milyang56 exhibited improved protein content, sodium dodecyl sulfate-sedimentation value, and loaf volume compared to Jokyoung, which were attributed to introgression of the Glu-B1i allele from the donor parent, cv. Garnet. SBS represents a flexible breeding model that can be applied by breeders for developing breeding materials and mapping populations, as well as analyzing the environmental effects of specific genes or loci and for trait stacking.