| Polyploid organisms often consist of novel characteristics,such as resistance to a variety of abiotic stresses;including cold and drought resistance.Possessing such characteristics are advantageous for the polyploid.In response to environmental stresses a plant will adjust by regulating changes in genomic methylation and gene expression.Arabidopsis thaliana the model plant of choose for plant biology,is a simple angiosperm consisting of a clear genetic background.Thus,understanding the effects of methylation and gene expression in response to abiotic stress in A.thaliana is essential for polyploid resistance research.In this study,we investigated the effects of salt stress on the molecular mechanism of polyploidy resistance in diploid and autotetraploid A.thaliana.For DNA markers identification 12 primer pairs was used for AFLP and MSAP analysis.Thus,the similarities and differences of methylation and genome stability were analyzed.Based on changes of the methylation patterns in the diploid and autotetraploid q-PCR was utilized to check the expression of 14 ABA receptor genes placed under different salt concentration.According to the relationship of expression level and salt concentration we found that PYL7 and PYL8 consist of similar expression patterns;such genes may have similarities in gene function.In order to verify the results,we cultivate the PYL7 Arabidopsis mutants,to study the function of PYL7 gene.The results of the study are as follows:1.Seed germinated in 150mmol/L salt concentration:For the control samples,germination rate was 98%(diploid)and 98%(tetraploid),the treatment group germinated at a rate of 62%(diploid)and 62%(tetraploid).Under high concentrations of salt(stress in 250 mmol/L)stress of the plant survival rate were 56%(diploid)and80%(tetraploid).For 150mmol/L under salt concentration,the relative root length increment of 13 mm diploid and tetraploid(control group)and 5 mm(diploid treatment group)and 10 mm(tetraploid treated groups).In conclusion,the tetraploid resist high concentration of salt than diploid.2.For Arabidopsis diploid and autotetraploid under salt stress,AFLP technique was used to check for genomic stability by counting the presence and absences of polymorphism bands.The diploid consist of no loss or increase,and in autotetraploid similar results was displayed.The results indicated that inducing the plants withdifferent levels of NaCl did not affect the contemporary plant genome,no mutations or variations were present,and thus this indicated that genome structure did not change.3.For MSAP methylation analysis on the root of Arabidopsis diploid and autotetraploid under salt stress treatment,12 primer pairs were employed for analysis purposes:(1)Arabidopsis diploid methylation level : Arabidopsis grew in normal circumstances,diploid Arabidopsis roots methylation level for 61% of the total rate of methylation,in which the methylation rate of 36.3%,half the methylation rate was24.7%.The overall total methylation rate is higher than the half methylation rate,with a variation of 11.6% between the two samples.After salt stress,the total methylation rate was 64.9%,the total methylation rate is 27.4%,half the methylation rate was37.5%.However,after salt stress the total methylation rate was decreased compared to the half methylation rate,10.1%.That salt stress lead to differentiation in genomic methylation patterns within a major adjustment.(2)Arabidopsis autotetraploid methylation level: Without salt treatment,the total methylation rate was 59.01%,the total methylation accounted for 26.9%,half methylation accounted for 32.11%.After salt stress,its total methylation rate into61.5%,the methylation rate of 30.56%,half the methylation rate was 30.94%.(3)Further analysis of diploid and autotetraploid methylation patterns change,the diploid compared no stress with treatment group is 72.6% of the methylation patterns change,tetraploid's change was 78.4%,the diploid singleton(S)is 27.3%.Polymorphism of methylation(M type)is 30.9%,the numbers of methylation(type D)accounted is 33.6% of the total numbers of methylation polymorphism amplification,indefinite type accounted for 8.1%.The tetraploid is: the singleton type(S)is21.7%;Polymorphism of methylation(M type)is 30.6%,and the control group in diploid flat,the numbers of methylation(D)accounted is 40% of the total Numbers of methylation polymorphism amplification,7% higher than diploid to methylation rate,not stereotypes accounted is 7.8%,rising to methylation rate as two major trends,than diploid and tetraploid growth rate is higher.4.In comparing the analyzed data with before and after salt induction,the total methylation rate for the diploid and tetraploid did not change significantly.However,the methylation and methylation percentage consist of serious adjument,especially the diploid,stress after half proportion of methylation rate have surpassed methylationrate,it maybe have significant relation.Compared with the diploid,the tetraploid homologous methylation patterns change significantly and this indicated that the methylation rate is lower than the demethylation rate.The same conclusion was obtained for tetraploid in comparison with the diploid.However,the tetraploid materials,data show that the demethylation rate is higher than the diploid.To further study the effects of salt in the polyploid plant in terms of similarities and differences of the Arabidopsis genome,the expression of ABA pathway receptor genes PYL1-PYL13 and PYR1,was analyzed,and the pyl7 mutant was bred further experimental use. |
PDF Full Text Request