糯小麦回交改良群体中Wx基因的遗传和品质效应

在基因型鉴定的基础上,利用糯小麦杂交后代BC5F2代回交改良群体研究了各基因缺失对降低直链淀粉含量的效果和各基因合成直链淀粉的能力,以及直链淀粉含量与农艺性状、品质性状、淀粉糊化特性等的相关性。研究发现,在Wx基因的所有8种基因型之间,直链淀粉含量差异显著;研究单缺失基因型发现,对直链淀粉含量减少效应最大的是Wx-B1b,减少效应最小的是Wx-A1b,而Wx-B1b和Wx-D1b没有显著差异;研究双缺失基因型发现,Wx基因合成直链淀粉的能力以Wx-B1a最高,Wx-A1a最低,而Wx-B1a和Wx-D1a差异很小.直链淀粉含量与株高、穗长、小穗数、穗粒数、千粒重等农艺性状相关不显著,表明淀粉品质育种可以与高产育种实现有机结合.直链淀粉含量与SDS-沉降值呈显著负相关(r=-0.726),说明直链淀粉含量降低在一定程度上有利于提高小麦营养与加工品质.全糯类型的淀粉糊化特性与其他类型显著不同,具有最高的峰值粘度和稀懈值,最低的低谷粘度、最终粘度、反弹值、峰值时间、糊化温度、起始糊化温度,表明糯小麦淀粉在食品和工业上具有特殊用途;稀懈值与直链淀粉含量呈极显著负相关(r=-0.969),其它粘度参数与直链淀粉含量呈显著正相关(最终粘度r=0.797,低谷粘度r=0.910、反弹值r=0.954、峰值时间r=0.970、糊化温度r=0.962、起始糊化温度r=0.932).表5参37

Genetic and Quality Effects of Wx Genes in Improved Backcross Progenies of Waxy Wheat

Based on the results of genotype identification,the waxy wheat's improved BC5F2 backcross progenies were used in this study to verify the effects of null alleles on reducing amylose content,determine the amylose synthesis capacity of each Wx gene,and investigate the correlation of amylose content with agonomic traits,quality traits and starch pasting properties,respectively.There was significant difference in amylose content of the eight genotypes carrying different null Wx alleles.The reducing effect of the single null alleles was most significant in Wx-B1b,followed by Wx-D1b and Wx-A1b,and no significant difference was observed between Wx-B1b and Wx-D1b.The results of the double null lines further demonstrated that in terms of the capacity of amylose synthesis,Wx-B1a had the highest effect,followed by Wx-D1a and Wx-A1a,and no significant difference was found between Wx-B1a and Wx-D1a.Amylose contents of the eight genotypes were not significantly correlated with plant height,spike length,spikelets per spike,grains per spike and 1 000-grain weight,indicating that starch quality breeding could integrate with high yield breeding.Amylose contents of the eight genotypes were negatively significantly correlated with SDS-sedimentation value(r=-0.726),suggesting that the reduction in amylose content is beneficial to improve quality at a certain extent.Starch pasting property of the full waxy type was significantly different from the other seven types,with the highest peak viscosity and breakdown,and lowest valley viscosity,final viscosity,setback,peak time,pasting temperature and starting pasting temperature,which indicated that waxy wheat starch had special use in food and industry.Breakdown was negatively significantly correlated with amylose contents(r=-0.969),and the other parameters were positively significantly correlated with amylose contents(r=0.797 for final viscosity,r=0.910 for trough viscosity,r=0.954 for setback,r=0.970 for peak time,r=0.962 for pasting temperature and r=0.932 for starting pasting temperature).The results of the study are useful for waxy wheat variety breeding and starch quality improvement.Tab 5,Ref 37