| Stalk Diameter（SD）and Rind Penetrometer Resistance（RPR）are two important indicators reflecting the strength of maize stalk,which are highly correlated with the lodging resistance of maize.Researching the genetic basis of SD＆RPR of maize stalk and exploring the key genes which control maize stalk SD and RPR are of great practical significance to improve the lodging resistance of maize.In this study,we constructed two sets of Recombinant Inbred Line（RIL）groups（hereinafter referred to as RIL1 and RIL2）by using maize inbred lines YS501 and LDC-1,Y915 and Zheng 58.The diameter of the second,third and fourth segment（SD2,SD3,SD4）and epidermal puncture strength（RPR2,RPR3,RPR4）were analyzed by using the phenotypic data in multi-year and multi-point environment and the multi-environment phenotypic data integrated by Best Linear Unbiased Prediction（BLUP）value.At the same time,a major Quantitative Trait Loci（QTL）for SD on chromosome 9 was verified and fine positioned.Main research results are as follows:1.By analysing the SD and RPR data of the parents of two sets of RIL groups in nearsurface internodes in the multi-year and multi-point environment,we could find that the SD and RPR of LDC-1 were notably higher than those of YS501.The SD of Y915 was notably higher than that of Zheng 58,but the RPR of Zheng 58 was notably higher than that of Y915.2.Integrating the results of QTL mapping for multi-environment and BLUP values,we detected 12,12 and 13 QTL respectively related to SD2,SD3 and SD4 in RIL1.These QTL were located on chromosomes 2,3,5,6,7,8,9 and 10,and LOD values were 2.58-12.98,which could explain 4.19%-21.72%of phenotypic variation.The distribution of these QTL on chromosomes was uneven,and 30 QTL of SD were enriched in 12 QTL clusters.It is worth mentioning that 10 QTL related to diameter were detected in the 114.3-131.5 cM region of chromosome 9.These QTL had the same additive effect direction and most of them peaked at 125.77 Mb,so we speculated that they might be the same QTL and named it as qSD9-2.Integrating the two mapping methods in RIL2,we detected 3 and 5 QTL associated with SD2 and SD3 on chromosomes 1,2,3,4 and 8,LOD values were 2.65-5.98,explaining 6.27%-14.95%of phenotypic variation.Among them,the physical intervals of q3SD3-1 in RIL2 and q3SD3-1 in RIL1 overlapped.3.Using the same method,we mapped QTL for RPR2,RPR3 and RPR4,and a total of 17,14 and 17 related QTL were detected.These QTL were distributed on all chromosomes,LOD values were 2.78-10.19,explaining 3.83%-14.95%of phenotypic variation.These QTL were not evenly distributed on all chromosomes,38 QTL of RPR were enriched in 12 QTL clusters.For example:in 228.9-264.0 cM on chromosome 1,54.0-75.0 cM on chromosome 2,118.4-138.9 cM on chromosome 5 and etc.In RIL2,2 and 3 QTL associated with RPR2 and RPR3 were detected by integrating two mapping methods.These loci were distributed on chromosomes 3,5,6 and 7,with LOD values of 2.86-5.48,explaining 6.75%-16.75%of phenotypic variation.Among them,the physical intervals of q3RPR5-1 in RIL2 and q3RPR5-1 in RIL1 overlapped.4.According to the resequencing results of parental,we developed 8 Indel markers in the qSD9-2 location range.6 recombinant plants were screened by using these markers.According to the correlation between genotype and phenotype of progeny population of recombinant plants,we further verified the authenticity of the QTL and narrowed the QTL interval to the physical interval of 9.97 Mb. |
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