Wu Jixiang, Jenkins Johnie N, McCarty Jack C, Saha Sukumar, Stelly David M
Department of Plant and Soil Sciences, Mississippi State University, Mississippi State, MS 39762, USA.
Theor Appl Genet. 2006 Feb;112(3):391-9. doi: 10.1007/s00122-005-0042-z. Epub 2005 Dec 9.
When using chromosome substitution (CS) lines in a crop breeding improvement program, one needs to separate the effects of the substituted chromosome from the remaining chromosomes. This cannot be done with the traditional additive-dominance (AD) model where CS lines, recurrent parent, and their hybrids are used. In this study, we develop a new genetic model and software, called a modified AD model with genotype x environment interactions, which can predict additive and dominance genetic effects attributed to a substituted alien chromosome in a CS line as well as the overall genetic effects of the non-substituted chromosomes. In addition, this model will predict the additive and dominance effects of the same chromosome of interest (i.e. chromosome 25 of cotton in this study) in an inbred line, as well as the effects of the remaining chromosomes in the inbred line. The model requires a CS line, its recurrent parent and their F(1) and/or F(2) hybrids between the substitution lines and several inbred lines. Monte Carlo simulation results showed that genetic variance components were estimated with no or slight bias when we considered this modified AD model as random. The correlation coefficient between predicted effects and true effects due to the chromosomes of interest varied from zero to greater than 0.90 and it was positively relative to the difference between the CS line and the recurrent line. To illustrate the use of this new genetic model, an upland cotton, Gossypium hirsusum L, CS line (CS-B25), TM-1 (the recurrent parent), five elite cultivars, and the F(2) hybrids from test-crossing these two lines with the five elite cultivars were grown in two environments in Mississippi. Agronomic and fiber data were collected and analyzed. The results showed that the CS line, CS-B25, which has chromosome 25 from line 3 to 79, Gossypium barbadense substituted into TM-1, had positive genetic associations with several fiber traits. We also determined that Chromosome 25 from FiberMax 966 had significantly positive associations with fiber length and strength; whereas, chromosome 25 from TM-1 and SureGrow 747 had detectable negative genetic effects on fiber strength. The new model will be useful to determine effects of the chromosomes of interest in various inbred lines in any diploid or amphidiploid crop for which CS lines are available.
在作物育种改良计划中使用染色体代换（CS）系时，需要将代换染色体的效应与其余染色体的效应区分开来。使用传统的加性-显性（AD）模型（该模型使用CS系、轮回亲本及其杂种）无法做到这一点。在本研究中，我们开发了一种新的遗传模型和软件，称为具有基因型×环境互作的改良AD模型，它可以预测CS系中代换的外源染色体所产生的加性和显性遗传效应，以及未代换染色体的总体遗传效应。此外，该模型还将预测自交系中同一目标染色体（即本研究中的棉花第25号染色体）的加性和显性效应，以及自交系中其余染色体的效应。该模型需要一个CS系、其轮回亲本以及它们之间的F(1)和/或F(2)杂种，以及几个自交系。蒙特卡罗模拟结果表明，当我们将这个改良的AD模型视为随机模型时，遗传方差分量的估计没有偏差或偏差很小。目标染色体的预测效应与真实效应之间的相关系数从零到大于0.90不等，并且它与CS系和轮回系之间的差异呈正相关。为了说明这个新遗传模型的用途，将一个陆地棉品种（陆地棉，Gossypium hirsusum L）的CS系（CS-B25）、TM-1（轮回亲本）、五个优良品种，以及这两个品系与五个优良品种测交得到的F(2)杂种种植在密西西比州的两种环境中。收集并分析了农艺和纤维数据。结果表明，CS系CS-B25（其第25号染色体从第3号到第79号，是来自海岛棉的染色体代换到TM-1中）与几个纤维性状具有正的遗传关联。我们还确定，来自FiberMax 966的第25号染色体与纤维长度和强度具有显著的正相关；而来自TM-1和SureGrow 747的第25号染色体对纤维强度具有可检测到的负遗传效应。这个新模型将有助于确定在任何有CS系可用的二倍体或双二倍体作物的各种自交系中目标染色体的效应。
