小麦PPO基因等位变异及面粉白度特性分析

利用分子标记PPO18和STS01对173份供试小麦品种Ppo 2A和Ppo 2D位点的等位基因变异进行分子检测，并根据品种间不同PPO等位基因组合类型将供试小麦品种进行分类，同时对多酚氧化酶PPO活性进行生化测定及面粉白度测定分析。结果表明，173份小麦品种共检测出Ppo A1b/Ppo D1a、Ppo A1b/Ppo D1b、Ppo A1a/Ppo D1a和 Ppo A1a/Ppo D1b 4种等位基因组合类型，且各基因组合类型出现的频率分别为38.7%、13.9%、35.8%和11.6%；供试小麦品种不同位点PPO等位基因出现的频率差异较大，2A位点等位基因Ppo A1a、Ppo A1b出现频率相近，而2D位点等位基因Ppo D1a出现频率是Ppo D1b的3倍；所测定的173份小麦品种PPO活性均值为117.3A₄₇₅/(min·mg) ，其中低PPO品种所占比例较高；4种基因组合类型PPO活性顺序为Ppo A1a/Ppo D1b>Ppo A1a/Ppo D1a>Ppo A1b/Ppo D1b>Ppo A1b/Ppo D1a ，且彼此间差异均达到显著水平(P<0.05)；供试小麦的面粉白度均值为73.0%，达到国家面粉白度等级一级标准的品种38份，占供试小麦总数的22.0%；其中基因组合为Ppo A1a/Ppo D1b的品种面粉白度显著低于其他3种基因组合。总体来看，供试的小麦品种间面粉白度及籽粒PPO活性变异范围较广，面粉白度与PPO活性呈显著负相关，且控制PPO的主效基因的等位变异对PPO活性及面粉白度均有显著影响。对供试小麦品种的面粉白度、PPO活性表现及PPO等位基因组合类型进行综合考察，筛选出23份具有高白度低PPO活性的小麦品种，可以作为高白度低PPO活性小麦育种的亲本材料。

Allelic Variation of PPO Genes and Analysis Properties of Flour Whiteness of Wheat Cultivars

The functional markers PPO18 and STS01 were used to investigate the presence of allelic variation at Ppo 2A and Ppo 2D loci of 173 wheat cultivars. The experimental materials were classified by different allelic gene combination type. The activity of PPO was detected by method of biochemistry and the flour whiteness in various allelic gene combination types was measured. Four allelic of combinations of PPO gene, Ppo A1b/Ppo D1a, Ppo A1b/Ppo D1b, Ppo A1a/Ppo D1a and Ppo A1a/Ppo D1b, were detected in 173 cultivars , and the frequencies of these allelic combinations were 38.7%, 13.9%, 35.8% and 11.6%, respectively. The frequency of PPO allelic genes on wheat chromosomes 2A and 2D was different. The frequency of allelic genes Ppo A1a and Ppo A1b on chromosome 2A was most alike, while the frequency of Ppo D1a was almost three times than that of Ppo D1b on chromosome 2D. The mean value of PPO activity in total experimental material was 117.3 A₄₇₅/(min·mg), and most of the cultivars were low PPO activity. The order of the PPO activity of cultivars with various allelic gene combinations was as follow: Ppo A1a/Ppo D1b>Ppo A1a/Ppo D1a>Ppo A1b/Ppo D1b>Ppo A1b/Ppo D1a and the differences of PPO activity between each combinations were the significant (P<0.05). The mean value of flour whiteness of experimental material was 73.0%. There were 38 cultivars which reach to the first level of national flour whiteness grade level. The flour whiteness of cultivars with the allelic gene combination Ppo A1a/Ppo D1b was significant lower than other three combinations. It is indicated that a wide variation of flour whiteness and PPO activities exists in these tested variations, and the PPO activity was negatively related to the flour whiteness. There was a significant negative correlation between flour PPO activity and whiteness, and allelic variations of major genes controlling PPO activity had significant effect on PPO activity. 23 wheat varieties with high flour whiteness and low PPO activity were selected according to the datas of flour whiteness, PPO activity and PPO gene combination. They can be used as the parent material of high white, low PPO activity wheat breeding work.