Biological Effect Of Mutagenesis Processing In Cassava And The Primary Filtration For Cold Resistance Mutants

As a result of the specific geographical position in our country, cold resistance is one of the important attribute which the hindrance cassava grows. North the cassava is a tendency and research aims today.This research take the cassava varieties as materials which Come from Variety resources research institute of the Chinese tropics agriculture Academy of Sciences, Treat the somatic embryogenesis and axillary buds of cassava with the chemical mutagenesis and physical mutagenesis. Chose the mutants from the aftergrowth and determine the mutation rates with morphologic observe and SRAP.And try to scalp the cold-resistance mutants through the low temperature.The results shown as followings:(1)Treat the 22 cassava varieties which spread broader in the Chinese area or has the special heredity characteristic. The range of the half lethal temperature of low temperature from 0.92℃to 6.63℃. The varieties can divide into four levels according to the cold-resistance: The half lethal temperature of the first level above 4℃, contain the varieties of OMR35-70-1 and SC6 ; the second level's half lethal temperature from 2℃to 4℃, contain the varieties of SC102,ZM8639,SM2323-6,SC201,CM610-2,SC8002,SC8;the third level's half lethal temperature from 1℃to 2℃, contain the varieties of SC8013,SC6068,ZM8641,ZM8803,SC5,KM98-5,KM98-1;the forth level's half lethal temperature from 0℃to 1℃, contain the varieties of SC124,SC205,BRA900,mianbao,ZM8316,KU50.The research has provided the reference for the idioplasm cold-resistant character appraisal, and provided the basis of the choice variety in further experimented.(2)Take the Cassava varieties SC8 and SC124 with plantlets of tissue culture as materials, induced the buds of the materials with ethylmethane sulfonate(EMS),complex treatment of EMS with benzamide,disthylsulfte (DES).The median lethal concentrations was confirmed: The median lethal concentrations of SC8 is 1.1%EMS,0.9%EMS+10mM benzamide,1.1%+5mM benzamide,0.4%DES;The median lethal concentrations of SC124 is 0.8%EMS,0.7%+5mM benzamide,0.5% EMS+10mM benzamide,0.3%DES. Through induced the axillary buds of the plantlets of tissue culture and the somatic embryogenesis with ⁶⁰Co-γradiation, has determined the influence of the materials in different radiation dose. The result shows that: the half lethal dose of the axillary buds is under 10 Gy;the half lethal dose of the somatic embryogenesis from 10Gy to 20Gy.(3)Found 8 different types mutagenesis plants through morphologic observe the aftergrowth in chemistry mutagenesis and the physical mutagenesis.The characterstable heredity including the purple leaf vein and petiole, the different color leaf, the spot leaf, the strumae leaf, the acerose leaf, the leaf shape variation, the leaf color variation.(4)Genetic diversity of the 4 cassava variety has been analyzied by SRAP. The 18 SRAP markers generated a total of 119 polymorphic alleles based on total of 78 varieties including 74 mutagenesis and 4 check. The results shown that: The heredity diversity is better in ⁶⁰Co-γmutagenesis of cassava.The range of the variation rate from 11.76% to 49.58%.The percentage of polymorphic loci is highest and the range of the variation rate is biggest in SC8. The mutagenesis of acerose leaf may be occurred in several polymorphic loci.There are more different types of mutagenesis in this colony.(5)The content of free proline in the two treatment is higher than the check of the SC124 and SC8. It stand a good chance to have cold-resistant mutants in the treatments of 0.3%EMS and 0.3%EMS+5mM benzamide of SC8.