Study On Mutagenic Effects Of The Rapeseed (Brassica Napus L) Induced By Space Flight And Combined Treatments With Sodium Azide

A preliminary study was made on the mutation effects by space flight and azide mutations in rapeseed(Brassica napus L),including 9313A,9313B,P100A,100B and M₂AB.In this paper,five materials were mutated with single or combined treatments by space flight(Satellite 'Shi-Jian 8',2006) and sodium azide(NAN₃).The mutagenic effects of these lines were studied.The main results were as follows:1.The results showed that the mitotic index was increased by space flight(SP),and it was remarkably decreased in the root-tip cells when it was treated with combined treatments compared with single treatment by space-flight.The rate of chromosome aberration was evidently higher with combined treatment than in single treatments.The rates of micronuclei were all comparatively high in the studied treatments,especially in space mutation.However,the rates of chromosome aberration and micronuclei were effectively reduced by azide treatment.It seemed that azide treatment was favorable for the repair of space mutation damagement.It was indicated that real cytological mutations were induced in the materials by space flight and sodium azide.The mutagenic effects were the same in male sterile lines and the maintainer lines.The mutagenic effects were observed higher in the maintainer lines than in the male sterile lines.2.Shown from the analysis of emergence rate and seedling rate,little effects of five rapeseeds were mutated by space flight.The rates of emergence and seedling were effectively reduced by azide treatment,and it was obviously decreased with the increasing time,especially it was performed for 24 h by NaN₃(N²⁴).The mutagenic sensitivity was different in five materials by NAN₃.M₂AB could not be beneficial to the mutation compared with other materials.Half the time of death was 12h in 9313B.The combined treatments were lowered restraining effect of NaN₃ in varying degrees.3.The growth duration of rapeseed M₁,showed that the start flowering stage and flowering end stage were obviously delayed by space flight,and the same effects were obtain when induced by N²⁴ and SP+N²⁴.The seedling stage was postponed by N²⁴ and SP+N²⁴ much later than other treatments in the male sterile lines.And the most obvious effect of delayed was using SP+N²⁴ in the seedling stage of M₂AB,10 days less than with N²⁴.On the start flowering stage,it was delayed 6 days compared with the control with both N²⁴ and SP+N²⁴ in "100" series materials,and delayed 21 days in M₂AB.The same effects were mutated by N²⁴ and SP+N²⁴ except 9313B.4.From the results of the field of SP₁,it was shown that many variation types appeared,including stems,branches,flowers and seeds.Some variations occured in the same types of plants,and the self-incompatibility arisesed in the individual plants.The mutagenic plants were observed that they are higher in the maintainer lines than in the other lines.Their frequency of variations was 1.6%.The variation of flower color was shown in 9313B,indicated that the color was white in the early flowering stage,and then it was turned to yellow in the flowering stage.The size of petal was changed in the 100 series lines.The smaller petals were shown in P 100A,and the larger petals were shown in 100B.5.It was shown in the results of the second-generation of the 90 lines.Compared with the other treatments,the strong growth was obvious in most of materials by space flight.In individual materials,the beginning of flowering was postponed and the sensitivity of frost damagement was weak.Its main mutated types were variation of stems,leaves,flowers and branches in SP₂.The stems were dwarfed in 9313B,and the high stems were displayed in 100B.Their frequency of variation was 20%and 16%respectively.The leaves of shallowing color were mainly mutated types,the size of leaves was bigger and the flowering stage was earlier than the others in one or two showed in these materials.It showed that the petals and the fertility were evidently mutated in the offspring,that its parents were mutated by space flight.And this type was not find in other mutation methods. It was indicated that the frequency and variation types occurred easily in offspring of treated parents.However,further studies are necessary for a better understanding about the mutations of real heredity.Some lines with the variation of the plant type were shown in 9313B,and its variations were the middle-branch type.The ration of separation was 3:1 in 50%lines.This variations were possibly induced by some or more control character genes of mutated,and further investigations are necessary for a better understanding about heredity mechanism.6.Some variation characteristics were investigated in rapeseed by single chemical or combined treatments.The variations of sterile plant were evidencely induced by combined treatments of SP+N²⁴ in M₂AB in M₁,and the rates of sterility were 7.16%higher than that of the control remarkably.In 9313B,the color of seed capsule was changed by combined treatments,and the type was hardly obtained by other methods in the contemporary. Meanwhile,the abundant types of variation were also showed in second-generation,such as the early-flower type,late-ripe type,strong type,middle-branch type and so on.With the combined treatments,the main types were stems,flowers,fruits in M₁,and the main types were stems,branches,leaves in M₂.The NaN₃ of chemical mutagen was seldom beneficial for the characters of botany.7.From the results of analysis of the quality characters of contemporary self-compatibility rapeseeds,it was shown that the oil content was higher than the control in male sterile lines by single chemical or combined treatments,the range of increase was 1%～4%.In contrast,the range of decrease was 3.3%～4.75%in male-sterile dual-use lines.And the oil contents were not vary in maintainer lines.The contents of oleic acid were remarkably increased in 100B and M2AB by treatments of N¹² and SP+N¹². Compared with the control it increased to 6%and 5.24%.It indicated that single chemical or combined treatments could promote contents of glucosinolate to increase remarkably in 100B.This case was happened in M₂AB on the contrary,9.66%decreased by SP+N¹² than that of the control.It seemed that the contents of erucic acid was also low for those mutation damages in all materials.8.The main objectives were obtained genetic resources of mutated quality characters. The results showed that the mutated effects were obviously increased by space-flight compared with other treatments.The little effects were induced by NAN₃,but the quality of contemporary self-compatibility rapeseeds were variated markedly.The results showed that it was ideal methods for 24 h by NaN₃ both the single-chemical treatment or combined treatment,because it possessed many virtues,such as little physiological damages,more mutated types and high frequeny of mutations.In this study,the mutagenic effects were observed higher in the maintainer lines than other lines both cytology and field character.It was indicated that the relativity was potentially existed between variations of chromosome and variations of offspring.It seemed that a prescient mechanism was availability delevoped by morphologic method and cytological method,which could be give some directions about offspring colony of mutated plant,and further researches are necessary for a better understanding.