| As a crop with distinct characteristics and extremely high economic and edible value on the Qinghai Tibet Plateau in China,highland barley is known as the "pearl ofthe plateau".In 2021,the planting area ofhighland barley in the Tibet Autonomous Region was about 2.11 million mu,with a yield of up to 801200 tons and a output value exceeding 3.2 billion yuan,accounting for 47.91%,61.54%,and 61.42% of the national planting area,yield,and output value of highland barley.However,with global climate change,powdery mildew caused by Brucella is becoming increasingly severe,and it continues to cause harm in various planting areas in China,becoming one of the important factors restricting the development of the highland barley industry.Powdery mildew mainly harms the leaves of plants,and in severe cases,it can harm parts such as stems and petioles(sheaths).Throughout the entire growth period of barley,it directly affects the yield and quality,causing significant economic losses,and ultimately affecting the development of the barley industry.Against the backdrop of continuous growth in planting area and yield,ensuring production safety is a major challenge faced by the barley industry.At present,it is known that the MLO(Mildew Locus O)gene is a plant specific recessive powdery mildew resistance gene.When a base deletion or mutation occurs,the plant can develop broad-spectrum resistance to powdery mildew.As a classic S gene,MLO has great potential in the development of broad-spectrum and long-lasting powdery mildew resistance germplasm.Understanding the MLO gene is also of great significance for high-yield and disease resistant breeding of highland barley.In order to clarify the breeding potential of barley for resistance to powdery mildew in China,as well as the resistance of barley germplasm resources to powdery mildew and the utilization of important disease resistance genes,this study conducted resistance identification on Tibetan farmhouse barley varieties and semi wild barley in Tibet,and screened disease resistant germplasm.The research results not only enriched the information of barley disease resistance gene resources,but also provided a reference basis for further research and rational utilization of disease resistant gene resources in the future.The main research findings are as follows:(1)Using powdery mildew strains to evaluate the resistance of 1524 agricultural varieties(lines)and 300 semi wild barley varieties from Tibet during the seedling and adult stages.The results of resistance identification showed that no immune varieties were found in the Tibetan farmhouse materials;Two immune varieties,YS-213 and YS-284,were found in the semi wild barley resources of Tibet,and both materials were naked grains,which can be used as resistant parents in barley breeding for resistance to powdery mildew.(2)Disease resistant control varieties L94 and YS-213,YS-284,ZYM-1288,Gannongda 7;Disease control materials: Tibetan 13,YS-133,Tibetan 0081,Tibetan 2000,and Winter 18.By comparing the above 10 germplasm genomes with known functional MLO gene sequences,sequence analysis revealed that there were 16 base variation sites in the germplasm sequence and 1 variation at the promoter 70 site.There are 6mutation sites in the exon region,located at 330,2033,2526,2917,3025,and 3028,respectively.The amino acids have not changed,indicating that all base mutations are synonymous and belong to synonymous mutations.There are 9 mutation sites in the intron region,located at 387,391,412,433,702,1719,2004,2082,2461.Based on the above analysis,it is speculated that the MLO gene is not the disease resistance gene causing the Tibetan local barley material,and may contain new disease resistance genes.In summary,this experiment preliminarily indicates that YS-213 and YS-284 in local materials from Tibet have reached the level of immunity throughout the entire growth period,and there may be new resistance genes to powdery mildew,providing a new source of resistance for cultivating long-lasting resistant varieties,which can be used for genetic improvement of disease resistance in highland barley and has high application value. |
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