中国小麦微核心种质资源PPO基因的等位变异

Allelic Variation of PPO Genes in Chinese Wheat Micro-Core Collections

【目的】小麦籽粒中的多酚氧化酶活性与面制食品的褐变密切相关。研究中国小麦微核心种质资源PPO活性的变异及其基因型的分布规律,为种质资源的合理利用以及中国面制食品外观品质的改良提供依据。【方法】以251份遗传多样性丰富的中国小麦微核心种质资源为试验材料,2004—2005年度种植于两个地点(安徽合肥、凤阳),采用生化和特异引物PCR扩增的方法对其PPO活性及基因型进行鉴定。【结果】中国小麦微核心种质资源品种间PPO活性差异明显,并且低PPO活性的品种居多;基因型、地点及其互作对PPO活性的影响达到1%显著水平。利用控制小麦PPO活性两个主效基因位点的特异PCR引物扩增结果表明,中国小麦微核心种植资源中共检测出PPO-2Aa1/PPO-2Da2(a1a2)、PPO-2Aa1/PPO-2Db2(a1b2)、PPO-2Ab1/PPO-2Da2(b1a2)和PPO-2Ab1/PPO-2Db2(b1b2)4种标记基因型,标记基因型间PPO活性均值的大小顺序为:a1a2<a1b2<b1a2<b1b2,方差分析表明均值间差异达1%显著水平,与环境互作分析表明标记基因型与地点的互作效应不显著(P<0.05)。小麦不同位点上的PPO等位基因出现频率有较大差异,2A染色体上PPO等位基因(2Aa1\2Ab1)出现频率相近,而2D染色体上PPO等位基因2Da2的出现频率约是2Db2的4倍。单倍型效应分析表明相同染色体上单倍型间的PPO活性关系为:PPO-2Aa1<PPO-2Ab1,PPO-2Da2<PPO-2Db2。对试验材料按照麦区,冬、春性以及地方和育成品种进行划分,结果表明华南冬麦区的小麦品种PPO活性均值最低,显著低于(P<0.01)西南冬麦区、三个春麦区(西北、东北和北部春麦区)和从国外引进的品种,其它麦区间的PPO活性差异不显著(P<0.01);来源于5个冬麦区的小麦品种的PPO活性均值显著(P<0.01)低于3个春麦区小麦品种的PPO活性均值;地方小麦品种的PPO活性均值最低,显著(P<0.01)低于育成品种和国外引进品种的PPO活性均值。此外,本文对中国小麦杂交育种中主要骨干亲本的PPO活性及基因型进行了分析。【结论】中国小麦微核心种质资源的品种间PPO活性差异明显,PPO主效基因等位变异对籽粒PPO活性有显著影响;中国小麦品种的PPO活性分布地域性规律明显,骨干亲本对小麦PPO活性及其基因型的分布有重要影响。

[Objective] Grain polyphenol oxidase （PPO） activity is highly related to the brown discoloration of wheat based end-products. Studying on the variation of PPO activity and the distribution of allelic genes in Chinese wheat micro-core collections could take good advantage of germplasm and improve the appearance quality of wheat flour food. [Method] In this study the variation of PPO activity and the distribution of PPO allelic genes were detected by the method of biochemistry and gene-based markers in 251 Chinese wheat micro-core collections growning in Hefei and Fengyang in 2004-2005 crop season. [Result] The results showed that most cultivars were with low PPO activity and the rate of varieties with PPO activity below 200 was 47.01% and the variation of PPO activity was affected by genotype and locations and interaction between them. Four genotypes, PPO-2Aa1/PPO-2Da2 （ala2）, PPO-2Aa1/PPO-2Db1 （a1b1）, PPO-2Aa1/PPO-2Db2 （a1b2）, and PPO-2Ab1/PPO-2Db2 （b1b2）, were detected in Chinese wheat micro-core collections. Cultivars with the genotype a1a2 have the lowest PPO activity while the cultirars with the genotype b1b2 have the highest, with genotype a1b2 and genotype b1a2 have the intermediate. The effect of interaction between marker genotypes and locations on PPO activity was not significant （P〈0.05）. The frequency of PPO allelic genes on two wheat chromosomes 2A and 2D was different. The frequency of allelic genes 2Aal and 2Abl on chromosome 2A was most alike, while the frequency of 2Da2 was almost four times than that of 2Db2 on chromosome 2D. The effect of haplotype of PPO genes on the same chromosome on PPO activity was PPO-2Aa1 〈PPO-2Ab1 and PPO-2Da2〈PPO-2Db2. The mean value of PPO activity of cultivars from South China Winter Wheat Region was significantly （P〈0.01） lower than that of cultivars from the three spring wheat regions and cultivars imported from aboard. Cultivars from the five winter wheat regions gave significantly （P〈0.01） lower PPO activity than cultivars from the three spring wheat regions of China. PPO activity of landrace was significantly （P〈0.01） lower than that of bred varieties and cultivars imported from aboard. The PPO activity and genotypes of primal parents in Chinese wheat cultivars was also analysized in this study. [Conclusion] Variation of PPO activity in Chinese wheat micro-core collections is obvious, and the allelic variation of PPO genes induced a significant effect on grain PPO activity. The distribution of wheat grain PPO activity and genotypes have a close relationship with wheat regions and wheat primary parents.