Study On Wheat Frost Difference And Molecular And Physiological Mechanism In The Different Varieties Of Wheat

Wheat is one of the world's three major cereals and one of the staple foods of mankind.In 2010,wheat became the second largest food crop in the world,second only to maize.Although the wheat has a wide range of adaptability,but different varieties due to different areas have a great difference in frost resistance.There are different degrees of frost damage occurred every year,which affected the yield of wheat seriously.It is important to compare the antifreeze difference of different wheat and analyze the mechanism of wheat frost resistance,which is of great significance to the breeding of wheat varieties with strong frost resistance.This study is mainly divided into two parts:the first part is the selection of 14 wheat materials for field trials.Sowing by stages,investigate the growth period and cold injury in early winter and winter of all varieties and detect vernalization and photoperiod genes.The second part is to select 6 varieties Ningmai4,Yangnuomail,Ningmai13,Yangmai11,Zhen 10375 and Yannong19 for pot experiment.In the case of artificial control of the temperature,determine physiological and biochemical changes during four panicle development stages of wheat leaves after low temperature stress.Exploring the physiological and biochemical responses of wheat after low temperature stress is to provide some theoretical basis and feasible method for the identification of wheat frost resistance.The main research results are as follows:1.The cold injury of different sowing stages results:there was little difference in frost injury between winter varieties of different sowing dates,basically tip slightly cold,belong to 1st level frost injury.Spring wheat sowing the earlier the heavier the freezing damage,freezing injury can reach the 4th-5th level in early sowing and highest up to 3rd level in suitable sowing.2.Freezing differences in different growth stages:Seedling known mainly leaves cold;into the jointing stage,the wheat vulnerable to frost damage,in addition to leaf frozen,more important is the stem and panicle frozen.3.The frost damage results of different varieties:among the 14 varieties,the frost damage of Ningmai4 is the heaviest,followed by Zhen10375,Yang 88-128 and Yangnuomail frost damage is serious,Nanda6,Ningmai13,Yangmai11,Yangmai22,Zheng9023 and Yangmail58 frost damage level is relatively light,Shi4185,Yannongl9,Zhongmai175 and Yumai2 frost damage the most light.4.The identification results of vernalization and photoperiod gene:vernalization gene detection showed that all varieties are recessive gene at the Vrn-A1 and Vrn-B3 loci.At the Vrn-B1 loci,except the Zheng9023 is the dominant genotype,other varieties are recessive gene.In Vrn-D1 locus,Yannong19,Zhongmai175,Yumai2 and Zheng9023 are recessive gene and the other 10 varieties are dominant gene.Photoperiod gene detection showed that all wheat varieties are the dominant gene Ppd-D1a,for photoperiod insensitive type.The varieties with recessive gene at 4 loci of vernalization gene have good cold resistance and the photoperiod gene is not directly related to the frost resistance.5.Effects of low temperature treatment on physiological indexes of four panicle development stages:In glume stage,soluble protein content and CAT activity increased first and then decreased,and the overall trend was increased and reached the maximum value at 12h after low temperature treatment.SOD and POD activity showed a gradual increase with time.The MDA content increased first and then decreased with the prolongation of time,and the overall trend was decreased and reached the maximum at 6h after low temperature treatment.In the pistil and stamen differentiation stage and anther differentiation stage,soluble protein content,SOD activity,POD activity and CAT activity of different varieties increased first and then decreased,and reached the maximum at 12h after low temperature treatment.The MDA content increased first and then decreased with the prolongation of time,and the general trend in pistil and stamen differentiation stage was decreased,and the general trend in anther differentiation stage was increased.In the four stage,the soluble protein content of all varieties showed an increasing trend,but amplitude was small.SOD activity,POD activity and CAT activity increased first and then decreased,but the overall trend was increasing.The MDA content of Ningmai4 increased first and then decreased,and MDA content of Yangmaill increased gradually,and other varieties increased first,then decreased and last increased.6.The wheat of pistil and stamen differentiation stage,anther differentiation stage the four stage is sensitive to the low temperature,and the anther differentiation stage is the most sensitive.It is not suitable to determine the frost resistance according to the degree of leaves cold damage in the four stage.7.To determine the frost resistance of wheat,it is the most direct method to investigate the damage degree of stem and leaf,and spikelet in the field.If the wheat frost resistance should be judged according to the related physiological indexes,using principal component analysis method instead of judging with a single physiological index is more accurate.