| An Aegilops tauschii mutant was identified from chemical mutagen N-methyl-N-nitrosourea (MNU) treated dry seeds of As2386. The mutant showed dwarfing in plant height and higher spike density. We investigated 24 morphological and agronomical traits.in M2 and M3 in two consecutive years. Seventy-nine SSR markers distributed in seven D chromosomes were used to evaluate the genetic similarity among the wild type, M2 and M3 plants. To test whether the reduced plant height is caused by gibberellic acid defection, we treated the mutant and wild type with gibberellic acid (GA3) and using double distilled water as controls. In addition, we made crosses between the mutant with eight Aegilops tauschii accessions and some morphological and agronomical traits in the F1 plants were investigated. The main results were as follows:1. Twenty-four traits were investigated. Among them,17 traits including first to fifth internode lengths, plant height, flag leaf length, top awn length, middle awn length, tillers per plant, effective ears per plant, ear length, spikes per plant, glume lenght, seed length, and seed aspect ratio and biomasses of the mutant were significantly smaller (or shorter) than those of the wild type (P=0.01). On the contrary, only four traits, including spikelet density, glume width, seed width and seed thick of the mutant were significantly larger than those of the wild type.2. The differences in ears, glume length and the spikelet density between the Aegilops tauschii mutant and other Aegilops tauschii accessions were easy to distinguish from each other. These traits in the F1 hybrid plants were dissimilar to the Aegilops tauschii mutant, on the contrary, they are very similar to the parental Aegilops tauschii accessions.3. A total of 79 SSR markers, specific to seven D chromosomes, were used for analysis the mutant M2, M3 and the wild type of Aegilops tauschii As2386. A total of 27 polymorphic SSR markers (34.2% of the total markers), with 2-7 markers in each D chromosome were detected between the mutant M2 and the wild type. However, there were more polymorphic markers between the wild type and the mutant M3. The total polymorphic markers between the wild type and the mutant M3 were 61 (77.2% of the total markers), with 5-12 polymorphic markers in each D chromosome. The polymorphic SSR markers detected between the mutant M2 and M3 (62), and within the M3 (58) were very similar; both were nearly equal to the total polymeric markers observed between the wild type and mutant M3. The GS coefficients between the pairs of the wild type and mutant M2, the mutant M2 and M3, and the wild type and mutant M3, were 0.7694,0.7201, and 0.6545, respectively, suggesting that the wild type was more similar to mutant M2 than mutant M3 in genetic background. The GS coefficients within M3 were more variable, ranged from 0.6449 to 0.8429, with an average of 0.7308, suggesting that the SSR patterns among M2 plants were variable.4. When treated with 50 mg/L gibberellic acid (GA3), the seeding of the mutant and the wild type showed yellow in color, thin, delicate, droop and breakage in stem while the seedings in the controls showed lilac, thick, strong, vertical and not easy to break. Compared with controls, the first leaf lengths of the wild type and the mutant in the gibberellic acid treated groups showed an increase of 32.46% and 35.69%, respectively, and the coleoptile lengths of them in the gibberellic acid treated groups showed an increase of 25.38% and 27.76%, respectively. The student’s t-test given significantly difference between the treated groups and control groups, suggesting that both the wild type and the mutant of Aegilops tauschii As2386 were sensitive to the gibberellic acid (GA3). |
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