Gene Screening And Identification For Arabidopsis Root Hairs Development

Dwarf and spaced planting is an important symbol of intensive cultivation in non-wood forest, which indicates one of the trends of future non-wood forest production. The current research about dwarf planting is mainly concentrated in the planting technology and mechanism of dwarf, while little attention has been paid for the dwarfing genes. Herein, we studied the effects of dwarf gene mutation to the development of root hairs in the model plant Arabidopsis.17 mutant strains of M3 seeds were screened and generated by treating Arabidopsis thaliana rhd3-1::GFP-HDEL seeds with ethyl methanesulfonate (EMS). Via preliminary observation of the root hair phenotype and genetic analysis of their M3 generations’seedlings, the single recessive nuclear mutant was identified for the further emphatically study.1. Screening of single recessive nuclear mutants:the root hair phenotype of M3 seedlings in the 17 mutant lines was observed under a steroscopic microscope, among them,8 mutant lines were steady and hereditary, and 5 of them were revealed as single recessive nuclear mutation (T1, T2, T4, T5, T6) via genetic analysis.2. Phenotype observation of 5 single recessive nuclear mutants:(1) The length of average root hair of 5 mutants was T5>T4>T1>T6>T2, and the root hair length of T1, T2, T5 and T6 seedlings were significantly lower than that of rhd3-1, p<0.05. In addition, the amount of average number of root hairs in the zone of 1.5 mm root maturation wasT1>T2>T6>T5>T4, and the average root hairs number of T2, T4, T5 and T6 were significantly less than that of rhd3-1, p<0.05.(2) The trichomes of seedling leaves of 5 mutant lines were observed using a steroscopic microscope. T4, T5 and T6 did not show obvious difference compared with rhd3-1 in the phenotype of trichomes, while T2 and T1 appeared conspicuous variations. The trichome of T1 leaf was unbranched and fat, and that of T2 was distorted with normal branches.(3)After cotyledons and leaves were removed, the morphology of endoplasmic reticulum (ER) in epidermal cells was observed by laser scanning confocal microscope. The endoplasmic reticulum of Tl, T2, T5 and T6 appeared different extent of variations compared with rhd3-1 mutant, except for T4.(4)The phenotype of Arabidopsis lines transplanted in nutrient soil was further observed. The average bolting time of WT and rhd3-1 mutant was 38.6 d and 36.2 d, respectively, and T1, T2, T4 and T5 was earlier than rhd3-1 mutant, while T6 was much later than rhd3-1 mutant. When the first stalk can be seen, the average number of rosette leaves of WT and rhd3-1 was 14.1 and 13.1, respectively. T1, T2, T4 was less than the number of rosette leaves in rhd3-1 mutant, and T5 was close to it, while T6 was significantly higher than rhd3-1 mutant. Furthermore, the adult plants of T1, T2, T4 were significantly shorter and smaller than that of rhd3-1.3. The preliminary forecast of mutation sites of T1 dwarf mutant lines were analysed by the MutMap method. We found the 450356 site in fifth chromosomes changed from base G to base A in T1 mutant.