Identification And Genetic Analysis Of Three Leaf Color Mutants In Maize

Maize(Zea mays L.) is one of the most important raw materials of food crops and feedingredients in the world. Most of its biological yield and economic yield are based onphotosynthesis. The leaf color mutant is the perfect experimental material during the researchof the plant photosynthesis mechanism and photomorphogenesis of the plant. In addition, alarge number of studies have found that there are same or similar mechanisms amongdifferent species, although the lesion mimic mutants have different phenotypes, differentdegrees of damage and different induced mechanisms. And this particularly shows moreresearch value in the study of disease resistance and programmed cell death.There are three different phenotype mutant materials, etiolated lesion mimic mutant,albino and viridescent leaf color mutant, used in this study. Among these, the yellow lesionmimic mutant derived from inbred lines81647. Before this study the gene of nec-t has beenlocated on the short arm of chromosome2(bin2.02), by the physical distance in a range ofaround131.7Kb. In this paper, we have done the allelic analysis between nec4and nec-t anddid some histochemical analysis about the death mechanism of yellow lesion mimic mutant.Albino mutants were also identified from inbred line81647, and they showed albino nomatter planted in incubator or field. The seedling was withered and died in the two-leaf orthree-leaf stage. There is no difference between albino and normal plants except the color ofleaf. Pale green mutant derived from inbred line22961which is not a lethal mutant. Theleaves of pale green mutant shows a pale green phenotype and growth retardation comparedwith normal seedling. But as time goes on, the virescent mutant plant will turn back greenagain progressively. In this paper, we mainly have done some genetic analysis and genemapping of the albino and pale green mutant. The main results are as follows:1Through the gene allelic analysis of the nec4and nec-t, we preliminary judge thatthey are actually the same gene.2. There are some obvious results after the histochemical analysis of yellow lesionmimic mutant and albino mutant. By using the trypan blue staining method it strongly proofs that the mutant cells have been dead and the DAB staining proves both of them accumulateda large amount of H2O2when them were going to die. The TUNEL experiments show thatprogrammed cell death is not the reason for the formation of necrotic lesion of lesion mimicmutant. The manner of the cell death could be necrosis resulted from the accumulation of theactive oxygen by the induction of light.3. By detecting the photosynthetic pigments of albino and virescent mutants, we foundthat albino mutants are total chlorophyll deletion mutants and virescent mutants are chladeletion mutants. These results suggested that the deficient in the photosynthetic pigmentpossiblely led to the albinism or virescent at the stage office seedling directly.4.MENGzi2inbred line was hybridized to the inbred line81647heterozygote with thealbino-gene in order to get F2segregating population. They have a same phenomenon whichF2generations trait segregation ratio of3:1, indicating that the albino is controlled by arecessive nuclear gene. By using the492albino mutant plants from F2segregating population,the albino mutant gene AS-81647(Albino seedling-81647) was located on the long arm ofchromosome3(bin3.09) of the maize, which was franked between SSR markers umc1052andumc1641with the genetic distances0.7cM and2.8cM, respectively and co-segregated withthe mark as47.5. Pale green mutant gene by inbred line23133was hybridized to inbred line22961forconstructing F2segregating population. For the genetic analysis and chi square test showingthat the virescent gene was controlling by a recessive gene. By using the F2segregationpopulation plants of the pale gene mutant, the pale green gene VS-22961(virescentseedling-22961) was mapped on the edge of centromere of chromosome1(bin1.05) betweenthe SSR markers umc1988and y178with genetic distance0.9cM,1.8cM, And the physicaldistance is about3MB, and co-segregated with y174, Y201, Y211, y248markers.