| Maize stalk fiber is major component of stalk cell wall, its quality directly affects maize stalkforage value, maize stalk strength and other economic characters. Therefore, study of the geneticbackground and mechanism of these traits may give an important guidance for the stalk fiber contentmolecular marker-assisted breeding. Total200and221recombinant inbred lines（RILs）were derivedfrom B73x By804(populationⅠ) and Zheng58x HD568(populationⅡ), respectively, which havedifferent genetic background. The two RILs were used to analyze genetic characteristics of maize stalkfiber traits and reveal numbers and effect of QTL by SNP genetic linkage map, combined withphenotype of six development stages at two locations in two years. The main results were as follows:1. With the development of growth stages, the change of ADL content was no obvious regularity,while CEL and HCEL content of both two populations showed declining trend at first and thenincreased with the development of growth stages. ADL, CEL and HCEL contents of populationⅠandpopulationⅡ range from1.52%～18.07%,12.68%～45.58%,11.04%～29.24%and0.94%～17.04%,12.01%～45.94%,19.11%～30.98%, respectively. The stalk fiber component had abundant geneticvariation.2. The analysis of variance showed that all the measured traits were significantly affected bygenotypes, locations (except ADL), stages and interaction among these factors.. The correlations werestrongly positive between CEL and HCEL, and between ADL and CEL at different growth stages of thetwo population. However, the correlations between ADL and HCEL were strongly negative at first, thenturned no significant, and became positive at last in populationⅠ; In populationⅡ, the correlationsbetween ADL and HCEL were strongly negative at first, then turned to positive, and became nosignificant at last.3.756SNP markers were used to construct the populationⅠgenetic linkage map, which covered atotal genetic length of1607.71cM, with an average maker interval of2.13cM. The QTL were detectedfor maize stalk fiber traits under single environment by inclusive interval mapping (ICIM) method.14,19,40QTL controlling ADL, HCEL and CEL were identified in the two environments, which explained5.91%～10.38%,6.54%～12.26%and3.84%～18.02%of the total phenotypic variation, respectively.The CEL QTL located in the SNP0623-SNP0626, SNP0485-SNP0489, SNP0626-SNP0629markerinterval on chromosome2, SNP1953-SNP1959marker interval on chromosome6, SNP2161-SNP2164,SNP2230-SNP2232, SNP2123-SNP2128marker interval on chromosome7were expressed amongmulti-stage or different environments.4.1358SNP markers were used to construct the genetic linkage map of populationⅡ, whichcovered a total genetic length of1985.21cM, with an average marker distance of1.46cM. A total of14,19,40QTL associated with the ADL, CEL and HCEL were found by ICIM mapping method under thetwo environments, which accounted for4.04%～12.93%,4.02%～13.95%and4.02%～13.95%of thetotal phenotypic variation. The CEL QTL located in the SNP0448-SNP0447, SNP0468-SNP0453,SNP0640-SNP0669marker interval on chromosome2, SNP2181-SNP2179marker interval on chromosome7, SNP2707-SNP2712marker interval on chromosome9were expressed amongmulti-stages or different environments.5. The results also indicated there may be presence of pleiotropism or linkage between genes,because we noted that several traits had co-located QTL. Interactions between the QTL was analyzedbased on mixed linear model. There were6pairs of epistasis detected in populationⅠ, and many QTLwere found in E-F stages. There were9pairs of epistasis detected in populationⅡ, and many QTL werefound in A-D stages. The QTLs on bin2.07and bin7.03could be detected in both of the twopopulations, which may play important roles in regulating stalk fiber synthesis. There are two QTL forCEL at bin2.07had overlapping confidence intervals in the two populations, and for each of the QTL,the percentage of contribution to the phenotypic variation was exceed10%. |
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