| EMS chemical mutagenesis technique, which is used as a common method to create new crop germplasm and improve plant agronomic traits, can induce maize to be mutant effectively. Improving the utilization of maize EMS mutation breeding research has very important practical significance. It can break through the bottleneck of maize breeding and make more excellent inbred lines and hybrid breeding be selected for maize production and application. Genetic evaluation and potential applications research of new mutations are the preconditions of using and studying. 19 EMS mutants and their test cross combinations by incomplete diallel crossing were used in this study. We analzyed the genetic difference between mutants and corresponding basic materal based on phenotypics characters,SSR makers and drought resistance, the difference of heterosis and combiming ability in main agronomic character of mutants combination, then gave a comprehensive evaluation of the breeding potential value. The major results were as follows:1. Genetic variation between EMS mutants and its basic line(1) The results of the phenotypic differences between K305 and its EMS mutants showed that mutants of K305 such as K305Y1403、K305Y1409、 K305Y1411 and K305Y1415 were different from K305. And there were 9 characters significant or extremely significant between K305 and them in the middle of 20 characters investigated in this study. Mutants R08Y1425、R08Y1423、R08Y1429 were different from R08. And there were 17,13,12 characters significant or extremely significant respectively.(2) The results of 40 SSR markers showed that each marker detected 3.8 and 4.2 alleles in K305 and R08, respectively. Numbers of genotype amplicate from them were 1.9 and 2.15 on average. Polymorphism information content (PIC) at each location of K305 and R08 group was 0～0.76 and 0～0.88, respectively, and its average PIC was 0.20 and 0.28.respectively. Genetic similarity coefficient of K305 and R08 between their mutants were 0.790～0.918 and 0.707～0.884, and their average genetic similarity coefficient were 0.862 and 0.809. According to the regulations of technology of corn cultivars for SSR marker method, different genetic locations of each mutation and their based materials K305 and R08 were two or above, which suggested that there were real genetic differences between base material and their mutations, and they expanded the germplasm resources.2. Applied potential of EMS mutants(1) Employing indoorsimulation system of drought stressing with 20% PEG-6000, five physiological traits of draught resistance, relative germination rate, soluble sugar stress index, MDA stress indexes, water loss rate of cutting leaves et al. were used to evaluated comprehensive draught resistance through fuzzy subordination method.4 mutant lines with highdrought resistance, R08Y1427, K305Y1413, R08Y1421 and K305Y1403, were screened for maize drought-resistance breeding. Additionally, Comprehensive analysis of drought resistance indicated that it provided an effective way for drought-resistance breeding of maize by treatment with EMS.(2) The combining ability effect of different mutants were different from basic material in different agronomic character. According to the general combining ability (GCA) of yield per plant, among K305 group, K305Y1405 and K305Y1407 were better than K305 on positive extremely significant, while among R08 group, mutant R08Y1435 and R08Y1439 were better than R08 on positive significant or extremely significant. It showed that the four mutants were easy to compare high-yielding combinations. According to special combining ability (SCA) of yield per plant from combinations, K389×K305Y1403、K318xK305Y1413、K318xK305Y1409、 21-ESxR08Y1439、21-ES×R081431 had better SCA,and better yield than the basic material.The five combinations might breednew varieties of maize.(3) The heterosis of EMS mutation combinations showed big changes. The corresponding heterosis of 30 combinations and unification heterosis of 24 combinations were positive significant or extremely significant in the group of K305, mutants K305Y1405 and K305Y1407 had better yield heterosis with tester. Correspondingly,20 and 5 combinations were positive significant or extremely significant in the group of R08, mutant R08Y1435 had better yield heterosis with tester than R08. Combinations HN231×K305Y140, K318xK305Y1409, K389xK305Y140, HN231xR08Y1435, HN231xR08Y1439, K389xR08Y1439 had better yield, better yield heterosis and better unilization in breeding practice.Comprehensive analysis showed that 5 SSR genetic locations were different between mutant R08Y1435 and R08. Per yield GCA effect of R08Y1435 was significantly higher than that of inbred line R08, while their drought resistances were same, and they were all moderate drought resistant material. Per yield GCA effect of K305Y1405 and K305Y1407 were significantly higher than that of inbred line K305, while their drought resistances were same. It suggested that their improved effect were better and utilization potentiality of them were better than base materials, so we can enhance the application in practice. Per yield of K389xK305Y1403 R08xK305Y1405 and 21-ESxR08Y1431 were all better than base materials, Per yield GCA effects were positive and significant different from their base material. The corresponding heterosis were positive significant or extremely significant, and unification heterosis were all more than 6% or extremely significant. They were all better combinations. So strengthening the selection in breeding practice, high yield maize varieties can be selected. |
PDF Full Text Request