Induction Of Tetraploid Wild Strawberry And Effect Of Low Temperature Stress On Tetraploid Fragaria Nigerrensis

Strawberry as the perennial herbaceous plant member of Rosaceae is an important berry crop in the world.There are nearly 20 common strawberries species worldwide and the ploidies of most strawberries mainly concentrate on the 2x,4x,6x and 8x.China owns rich wild Fragaria species and cultivated strawberry are widely planted.The varieties of wild strawberries which distribute naturally is 11,three of which are tetraploids.The study on tetraploid induction by utilizing wild strawberries resources was to enrich the germplasm resources,provide a material basis for further research.1.Identification hybrids reliability on interspecific hybrids of F.Viridis × F.Mandschurica through biological characteristics observing,chromosome counting,SRAP molecular markers,etc.And the sterile interspecific hybrid LsDb-11-01 was used as material to study the effect of chromosome doubling of diploid hybrid by treating with oryzalin and colchicine on the basis of in vitro propagation.The result showed that the phenotype of hybrids differed from parent,chromosome counting and SRAP molecular markers identified that interspecific hybrids were potential hybrids.Compared with the polyploid induction effectiveness of oryzalin and colchicine preliminarily,it was discovered that the treatment with 0.1%colchicine for 48 h performed better than oryzalin,18 tetraploid lines were obtained.2.The leaves of in vitro Fragaria nilgerrensis were used to study the influences of different plant growth regulator combination on shoot regeneration;and the shoots in vitro were employed to research the effects of colchicine at different concentration and treatment times on chromosome doubling.The shoots in vitro induced by colchicine were detected through flow cytometry technique and chromosome counting.The results showed the best medium for in vitro F.nigerrensis shoot regeneration was MS +1.0 mg·L-1 TDZ +0.1 mg·L-1 IB A on which the shoot regeneration was up to 73.19%;the highest mutation rate was 13.33%under treatment of 0.15%colchicines for 48 h,12 autotetraploid lines were obtained by chromosome counting.3.Tetraploids of Fragaria nilgerrensis in vitro were used as material,to determine and analyze the dynamic changes on activities of SOD,POD,CAT and MDA content in leaf of diploid of Fragaria nilgerrensis and tetraploid strains under low temperature stress(0 ?)with different length of time.The results showed that with prolonging of stress time,activities of POD,SOD,CAT in general appeared the trend of firstly increasing and then decreasing.Furthermore,the increasing ranges of these in tetraploid leaf were obviously higher than those in diploid leaf of Fragaria nilgerrensis.The MDA content totally appeared gradually increasing trend in leaf of both diploid and tetraploid plants,and MDA content of tetraploid leaf were lower than diploid's.The comprehensive analysis result showed preliminary that protective enzyme activity in leaf of tetraploid of Fragaria nilgerrensis were higher and cold resistance might be better than those in diploid of Fragaria nilgerrensis.