Using SSR and SNP Markers for QTL Analysis of Maize Against Aspergillus Flavus
|Keywords||ma(?)e Aspergillus flavus SSR markers SNP markers QTL|
Maize (Zea mays L.), one of main crops in the world, is easily susceptible to Aspergillus flavus (A. flavus) infection. A. flavus can produce highly toxic aflatoxin. Long-term intake of small doses of aflatoxin will cause chronic poisoning. For animals, aflatoxin can lead to liver function decline, reduce the milk yield and the rate, lower the animal’s immunity, vulnerable to infect harmful microbes, digestive disorders, reduce fertility and the utilization rate of feed, and even cause anemia and the embryo poisoning, etc. For human health, aflatoxin is a big security risk, people eating food which was polluted by aflatoxin would cause harm to human health. Tt is very difficult for the pollution prevention. Therefore, breeding for A. flavus resistance in mazie has been proved an efficient way to minimize the losses.A recombinant inbred line (RIL) population derived from RA, a maize inbred line resistant to A. flavus infection, and M5P, a susceptible inbred line, was developed. This research choose a total of242family, the seeds from each lines planted in three years of2010\2011\2012were inoculated with A. flavus and evaluated for infection level, and use molecular markers for detection, the main results are as follows:1.Phenotypic data analysis shows that:the differences between the parents are obviously. The genotype of individuals between family, the effect of the interact between genotype and environment are all reached extremely significant level. That is to say, the A. flavus resistance in mazie was controlled by genotype, there is interaction between genotype and environment effects.2.From826pairs of SSR primers screened205pairs of polymorphic primers, polymorphism rate was24.8%, including191clear bands can be used for quantitative trait loci(QTL) mapping. Also1238polymorphic markers were screened from3072SNP markers, polymorphism rate was40.1%, choose740SNP markers for final positioning.A total of931markers used to construct a molecular marker linkage map which was covered10maize chromosomes, the full length was1367cM, the average distance of flanking markers was1.5cM, the mapping altogether fit916molecular markers. 3.This study used Wincartographer software which based on composite interval mapping (CIM) method and QTL network-2.0software which based on mixed composite interval mapping (MCIM) method to analysis A. flavus resistance, the results show that:(1) eight QTL were detected by using CIM method, respectively located in chromosome5,6,8, and10, LOD value were2.12-5.38, explained3.75%-9.87%phenotypic variation, there is only one QTL were detected in three environments;(2) one additive QTL was detected by using MCIM method, located in chromosome5, contribution rate was11.37%. Three pair of epistatic QTL were detected, the effect of the interact between epistatic and environmental was reached extremely significant level. The CIM and MCIM method detected the same QTL which was located on chromosome5,bin value was5.03, has the highest contribution rate in all of the QTLs, the QTL can be regarded as the main effect of A. flavus resistance in mazie.Cultivating resistant maize hybrid can reduce aflatoxin contamination, and reduce the harm to human and animal. This study can identify the QTL which was associated with A. flavus resistance in maize, laid the foundation for cloning of resistance genes, provide theoretical and material guarantee for breeding work.