| Impatiens balsamina L.as traditional garden ornamental flowers,possesses a long flowering period,strong adaptability,colorful appearance and the wide range of planting.The ala of Impatiens balsamina is as light as birds and in a graceful shape.Antibacterial,anti-inflammatory,anti-cancer and other physiologically active substances can be isolated from Impatiens;it is a garden plant with ornamental and practical value.Mutant Impatiens was obtained from the treatment of space condition.We focus our preliminary study on aspects of morphophysiology,cytology,variety breed,etc.In order to uncover the relationship between the genetic variation and phenotype caused by mutagenesis further,we studied the difference of the mutant plant in physiological responses of resistant and gene expression under stress condition,which could be used as a guide for the cultivation of Impatiens and the method to improve varieties and resistant genes screening.In this study,the sample were the SP10 of Xihang No.2,which was cultivated and selected among the mutant plants of Impatiens balsamina,whose seeds had shown stable traits for two years of planting and had been sent into spacecraft with Shenzhou 4 in 2002 by Nanchong Aerospace Breeding Center,Sichuan.Five years of field cultivation experiment and laboratory cultivation experiment were carried out.Morphological observation,determination of photosynthetic characteristics and fluorescent quantitative PCR in petal control genes of DEF1 and DEF2 were implemented.Under the condition of artificial control,stress treatment was performed.Then the seed germination,stress-tolerant enzymes activity,and the expression of anti-related gene were identified.RAPD molecular marker analysis was performed on the seedling of Impatiens acquired from the modified MS medium.The main results are as follows:1.Results of field cultivation indicated that the traits of induced Impatiens were not only stable,but also shorter and spunkier than that of common Impatiens.The change of the morphological characteristics of the leaves of Impatiens attenuated the water loss;the plant became more resistant to drought than ordinary Impatiens,so this mutation is favorable.Impatiens whose light saturation point of Impatiens is in the vicinity of 800?mol / m2 s,was not resistant to strong light and suitable for growing at the edge of the forest filled with shoot light.The flower of mutant Impatiens is larger and its flowering phase can reach a length of 80 days from May to July,a season with high temperature.2.In this study,the lower chlorophyll content and photosynthetic rate in mutant offspring meant lower accumulation of photosynthetic products and biomass,which was consistent with the result observed in the field that the mutant plants were shorter than the normal plants in height.Since the mutant plants have a slower photosynthetic rate than the normal ones,they accumulated less organic substances per unit time.Thus it will take time to complete its life cycle.3.We use different concentrations of PEG-6000 solution to treat the mutant and common Impatiens and determine the related protective enzyme activities.The results of drought stress simulation with PEG-6000 indicate that the SOD activity of mutant Impatiens increased significantly under a slight drought stress simulation;about three times of the CK and MDA content did not increase significantly compared with the control,implying that mutant Impatiens are extremely sensitive to water deficit,and the protective enzyme system responded quickly to protect plants from stress.The results of salt stress simulation of NaCl showed that the activities of CAT,SOD and POD were significantly increased with the increase of salt concentration,and the content of MDA did not change significantly compared with the control,reflecting that mutant Impatiens has a certain tolerance to salt of low concentration.4.Through fluorescence quantitative analysis,we found that the changes of petal morphology and quantity of mutant Impatiens were linked to the differential expression of DEF2.SOS2 and RD29 B genes were associated with the regulation of responses to drought stress under the condition of water deficit;particularly the expression level of RD29 B gene was 9 times higher than CK conditions,and the gene had a high correlation with drought stress.The effects of SOS2 and RD29 B genes on common Impatiens were not significant.SOS2 and RD29 B genes did not play a major role in Impatiens under salt stress.5.17 random primers were selected for RAPD analysis and every primer was amplified clear bands.A total of 81 clear bands were amplified,with a molecular weight between 200-2000 bp.Each primer was amplified 8 bands at most and 2 bands at least.The amount of polymorphic primers were 8,accounting for 47.06% of all random primers;and the number of polymorphic bands were 12,accounting for 16.05% of the total.The results of electrophoresis of DNA polymorphism detection on two samples of the same strain showed the similarity between the two samples from genetic similarity analysis,indicating that many genetic material has undergone a qualitative change after genetic mutation,suggesting that some corresponding gene may have been mutated and the changes in characters has been caused by the change of some functional genes. |
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