通过全基因组关联分析和连锁图谱鉴定及验证热带玉米中与抗炭腐病相关的基因组区域

Identification and Validation of Genomic Regions Associated With Charcoal Rot Resistance in Tropical Maize by Genome-Wide Association and Linkage Mapping.

作者信息

Rashid Zerka, Kaur Harleen, Babu Veerendra, Singh Pradeep Kumar, Harlapur Sharanappa I, Nair Sudha K

机构信息

International Maize and Wheat Improvement Center (CIMMYT), ICRISAT Campus, Hyderabad, India.

Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, India.

出版信息

Front Plant Sci. 2021 Oct 8;12:726767. doi: 10.3389/fpls.2021.726767. eCollection 2021.

Abstract

Charcoal rot is a post-flowering stalk rot (PFSR) disease of maize caused by the fungal pathogen, . It is a serious concern for smallholder maize cultivation, due to significant yield loss and plant lodging at harvest, and this disease is expected to surge with climate change effects like drought and high soil temperature. For identification and validation of genomic variants associated with charcoal rot resistance, a genome-wide association study (GWAS) was conducted on CIMMYT Asia association mapping panel comprising 396 tropical-adapted lines, especially to Asian environments. The panel was phenotyped for disease severity across two locations with high disease prevalence in India. A subset of 296,497 high-quality SNPs filtered from genotyping by sequencing was correcting for population structure and kinship matrices for single locus mixed linear model (MLM) of GWAS analysis. A total of 19 SNPs were identified to be associated with charcoal rot resistance with value ranging from 5.88 × 10 to 4.80 × 10. Haplotype regression analysis identified 21 significant haplotypes for the trait with Bonferroni corrected ≤ 0.05. For validating the associated variants and identifying novel QTLs, QTL mapping was conducted using two F populations. Two QTLs with overlapping physical intervals, qMSR6 and qFMSR6 on chromosome 6, identified from two different mapping populations and contributed by two different resistant parents, were co-located with the SNPs and haplotypes identified at 103.51 Mb on chromosome 6. Similarly, several SNPs/haplotypes identified on chromosomes 3, 6 and 8 were also found to be physically co-located within QTL intervals detected in one of the two mapping populations. The study also noted that several SNPs/haplotypes for resistance to charcoal rot were located within physical intervals of previously reported QTLs for Gibberella stalk rot resistance, which opens up a new possibility for common disease resistance mechanisms for multiple stalk rots.

摘要

炭腐病是由真菌病原体引起的玉米花后茎腐病。由于产量大幅损失以及收获时植株倒伏,它是小农玉米种植的一个严重问题,并且预计随着干旱和土壤高温等气候变化影响,这种病害将会激增。为了鉴定和验证与炭腐病抗性相关的基因组变异,对国际玉米小麦改良中心亚洲关联定位群体(由396个适应热带环境的品系组成,尤其适应亚洲环境)进行了全基因组关联研究(GWAS)。该群体在印度两个病害高发地点进行了病害严重程度的表型分析。通过测序基因分型筛选出的296,497个高质量单核苷酸多态性(SNP)进行子集分析,针对全基因组关联分析的单基因座混合线性模型(MLM)校正群体结构和亲缘关系矩阵。共鉴定出19个与炭腐病抗性相关的SNP,其值范围为5.88×10至4.80×10。单倍型回归分析确定了该性状的21个显著单倍型,经Bonferroni校正后P值≤0.05。为了验证相关变异并鉴定新的数量性状位点(QTL),使用两个F群体进行了QTL定位。在6号染色体上鉴定出两个具有重叠物理区间的QTL,即qMSR6和qFMSR6,它们来自两个不同的定位群体且由两个不同的抗性亲本贡献,与在6号染色体103.51 Mb处鉴定出的SNP和单倍型共定位。同样,在3号、6号和8号染色体上鉴定出的几个SNP/单倍型也在两个定位群体之一中检测到的QTL区间内物理共定位。该研究还指出,几个抗炭腐病的SNP/单倍型位于先前报道的抗赤霉茎腐病QTL的物理区间内,这为多种茎腐病的共同抗病机制开辟了新的可能性。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/4cdf/8531636/6369d0f69562/fpls-12-726767-g0001.jpg

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