| Maize is the second most widely distributed grain crop after wheat in the world. China is the second largest corn producing country, with respect to its total output and planting area in the world. In China, maize is known as" the king of the feed" due to its importance in food, economic and feed. In the world about70%-75%of the maize is being used for animal feed and in China,78%of the total maize production is demanded for livestock and poultry feed. According to an estimate, by2030, China should reach up to220million tons of maize production, which can satisfy the basic domestic needs. Thus increasing maize production plays an important role in the sustainable development of agriculture in China.Yield is an important factor in agriculture which is affected by so many factors. All over the world, scientists are trying to enhance the yield by applying advanced molecular techniques. In breeding process, selection is based on yield traits. In this study,222F2.4populations, derived from a cross between Shen3336x Shen3265were used to analyze the genetics and QTL associated with Chlorophyll and yield related traits. The main results as followed:1. In this study, genetic analysis of number of kernels per row, ear length and number of rows per ear were conducted by joint segregation analysis of four generations P1, P2, F1and F2.4from the cross Shen3336x Shen3265using the mixed major genes and polygenes inheritance models. Seeds of these generations were grown in three replications using randomized complete block design. The results showed that number of kernels per row, ear length and number of rows per ear were controlled by polygenes and two major genes having additive dominance effects. Twenty four different genetic models were applied and the model C-0(Additive-dominance-epistatic polygene), B-1(two additive-dominance major genes) and B-2(two Additive-dominance genes) were found to be best fit for number of kernels per row, ear length and number of rows per ear as tested by statistical analysis, respectively. The heritability of these traits (number of kernels per row, ear length and number of rows per ear) was53.7%,19.8%and17.2%, respectively.2. Genetics of chlorophyll revealed that chlorophyll "a" was controlled by two main gene having additive-dominance-epistasis effects. The heratibility of these genes was56.3%. Chlorophyll "b" was controlled by two pairs of codominant major gene plus additive-dominance polygene. The heratibility of these major genes and polygenes were 1.12%and93.26%respectively. Chlorophyll "a+b" was controlled by two pairs of additive-dominance-epistatic major genes plus additive-dominance poly gene having heratibility of56.2%and5.2%respectively.3. The genome DNA of maize was extracted by improved CTAB method, which showed high quality, integrity and without RNA contamination was detected on0.8%agarose gel electrophoresis. The extracted genomic DNA could be potentially used for PCR amplification reactions.4. To identify QTLs of yield traits in maize,530SSR markers were screened between parents for polymorphism. Among these,85primers showing distinct polymorphism were used to detect QTLs in222individuals of F24populations. Twelve QTLs were found on chromosome1,2,4,6,7,8and9. One QTL for ear length and number of rows per ear was found on2and7chromosomes, respectively. Phenotypic variance associated with these QTLs was5.6812and5.6219, respectively. Seven QTLs were found for kernel number per row having dominance and additive effects ranged from4.4272-5.7058and1.9573-2.1604, respectively. The phenotypic variance explained for these QTLs varied from40.8926-56.5709. Three QTLs for Chlorophyll content were detected on chromosome1and6explaining phenotypic variance range of6.4653to7.3295%having partial and over dominance gene action. These QTLs identified in this study may be useful for marker assisted selection in maize breeding programs for yield improvement. |
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