Tamang Prabin, Richards Jonathan K, Solanki Shyam, Ameen Gazala, Sharma Poudel Roshan, Deka Priyanka, Effertz Karl, Clare Shaun J, Hegstad Justin, Bezbaruah Achintya, Li Xuehui, Horsley Richard D, Friesen Timothy L, Brueggeman Robert S
Department of Plant Pathology, North Dakota State University, Fargo, ND, United States.
Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA, United States.
Front Genet. 2021 Jan 15;11:601500. doi: 10.3389/fgene.2020.601500. eCollection 2020.
Barley is an important cereal crop worldwide because of its use in the brewing and distilling industry. However, adequate supplies of quality malting barley are threatened by global climate change due to drought in some regions and excess precipitation in others, which facilitates epidemics caused by fungal pathogens. The disease net form net blotch caused by the necrotrophic fungal pathogen f. () has emerged as a global threat to barley production and diverse populations of have shown a capacity to overcome deployed genetic resistances. The barley line CI5791 exhibits remarkably effective resistance to diverse isolates from around the world that maps to two major QTL on chromosomes 3H and 6H. To identify genes involved in this effective resistance, CI5791 seed were γ-irradiated and two mutants, designated CI5791-γ3 and CI5791-γ8, with compromised resistance were identified from an M population. Phenotyping of CI5791-γ3 and -γ8 × Heartland F populations showed three resistant to one susceptible segregation ratios and CI5791-γ3 × -γ8 F individuals were susceptible, thus these independent mutants are in a single allelic gene. Thirty-four homozygous mutant (susceptible) CI5791-γ3 × Heartland F individuals, representing 68 recombinant gametes, were genotyped via PCR genotype by sequencing. The data were used for single marker regression mapping placing the mutation on chromosome 3H within an approximate 75 cM interval encompassing the 3H CI5791 resistance QTL. Sequencing of the mutants and wild-type (WT) CI5791 genomic DNA following exome capture identified independent mutations of the transcription factor located on chromosome 3H at ∼50.7 cM, within the genetically delimited region. Post transcriptional gene silencing of in barley line CI5791 resulted in susceptibility, confirming that it functions in NFNB resistance, validating it as the gene underlying the mutant phenotypes. Allele analysis and transcript regulation of from resistant and susceptible lines revealed sequence identity and upregulation upon pathogen challenge in all genotypes analyzed, suggesting a conserved transcription factor is involved in the defense against the necrotrophic pathogen. We hypothesize that functions as a conserved signaling component of defense mechanisms that restricts growth in barley.
大麦是一种在全球范围内都很重要的谷类作物，因为它被用于酿造和蒸馏行业。然而，由于一些地区干旱和其他地区降水过多，全球气候变化威胁到了优质麦芽大麦的充足供应，这助长了由真菌病原体引起的流行病。由坏死营养型真菌病原体网斑病菌（Pyrenophora teres f. teres）引起的网斑病已成为对大麦生产的全球威胁，并且该病菌的不同种群已显示出克服已部署的遗传抗性的能力。大麦品系CI5791对来自世界各地的不同网斑病菌分离株表现出显著有效的抗性，该抗性映射到3H和6H染色体上的两个主要数量性状位点（QTL）。为了鉴定参与这种有效抗性的基因，对CI5791种子进行了γ射线辐照，并从M2群体中鉴定出两个抗性受损的突变体，命名为CI5791-γ3和CI5791-γ8。CI5791-γ3和-γ8与Heartland F1群体的表型分析显示出3抗性：1感病的分离比例，并且CI5791-γ3×-γ8 F2个体是感病的，因此这些独立的突变体位于单个等位基因中。通过PCR基因分型测序对34个纯合突变体（感病）CI5791-γ3×Heartland F2个体进行基因分型，这些个体代表68个重组配子。这些数据用于单标记回归定位，将突变定位在3H染色体上一个大约75厘摩（cM）的区间内，该区间包含3H CI5791抗性QTL。在进行外显子捕获后，对突变体和野生型（WT）CI5791基因组DNA进行测序，确定了位于3H染色体上约50.7 cM处、在遗传界定区域内的转录因子的独立突变。在大麦品系CI5791中对该转录因子进行转录后基因沉默导致感病，证实了它在对网斑病菌的抗性中起作用，验证了它是突变体表型的基础基因。对来自抗性和感病品系的该转录因子的等位基因分析和转录调控显示，在所有分析的基因型中，病原体攻击后序列相同且上调，这表明一个保守的转录因子参与了对坏死营养型病原体的防御。我们假设该转录因子作为防御机制的一个保守信号成分，限制了网斑病菌在大麦中的生长。
