Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, 55108, USA.
BMC Genomics. 2010 Nov 23;11:653. doi: 10.1186/1471-2164-11-653.
Advanced cycle breeding utilizes crosses among elite lines and is a successful method to develop new inbreds. However, it results in a reduction in genetic diversity within the breeding population. The development of malting barley varieties requires the adherence to a narrow malting quality profile and thus the use of advanced cycle breeding strategies. Although attention has been focused on diversity in gene expression and its association with genetic diversity, there are no studies performed in a single breeding program examining the implications that consecutive cycles of breeding have on gene expression variation and identifying the variability still available for future improvement.
Fifteen lines representing the historically important six-rowed malting barley breeding program of the University of Minnesota were genotyped with 1,524 SNPs, phenotypically examined for six malting quality traits, and analyzed for transcript accumulation during germination using the Barley1 GeneChip array. Significant correlation was detected between genetic and transcript-level variation. We observed a reduction in both genetic and gene expression diversity through the breeding process, although the expression of many genes have not been fixed. A high number of quality-related genes whose expression was fixed during the breeding process was identified, indicating that much of the diversity reduction was associated with the improvement of the complex phenotype "malting quality", the main goal of the University of Minnesota breeding program. We also identified 49 differentially expressed genes between the most recent lines of the program that were correlated with one or more of the six primary malting quality traits. These genes constitute potential targets for the improvement of malting quality within the breeding program.
The present study shows the repercussion of advanced cycle breeding on gene expression diversity within an important barley breeding program. A reduction in gene expression diversity was detected, although there is diversity still present after forty years of breeding that can exploited for future crop improvement. In addition, the identification of candidate genes for enhancing malting quality may be used to optimize the selection of targets for further improvements in this economically important phenotype.
高级循环育种利用优秀品系之间的杂交，是开发新自交系的成功方法。然而，这会导致育种群内遗传多样性的减少。麦芽大麦品种的发展需要遵循狭窄的麦芽质量概况，因此需要使用高级循环育种策略。尽管人们已经关注基因表达的多样性及其与遗传多样性的关联，但在单个育种种群中，没有研究连续的育种循环对基因表达变异的影响，并确定未来仍可用于改进的可变性。
代表明尼苏达大学历史上重要的六棱麦芽大麦育种计划的 15 个品系，通过 1524 个 SNP 进行了基因型分析，通过 Barley1 GeneChip 阵列对六个麦芽质量性状进行了表型检测，并对萌发过程中的转录积累进行了分析。遗传变异与转录水平变异之间存在显著相关性。我们观察到，尽管许多基因的表达尚未固定，但在育种过程中遗传和基因表达多样性都有所减少。鉴定出许多与表达固定在育种过程中的质量相关基因，表明多样性减少的大部分与“麦芽质量”这一复杂表型的改善有关，这是明尼苏达大学育种计划的主要目标。我们还鉴定了该计划最近的品系之间的 49 个差异表达基因，这些基因与六个主要麦芽质量性状中的一个或多个相关。这些基因构成了在育种计划中提高麦芽质量的潜在目标。
本研究显示了高级循环育种对重要大麦育种计划中基因表达多样性的影响。尽管经过四十年的育种，基因表达多样性有所减少，但仍存在多样性，可用于未来的作物改良。此外，鉴定出增强麦芽质量的候选基因可用于优化选择进一步改进这一经济重要表型的目标。
