Studies On The Establishment Of System In Vitro Regeneration And Octoploid Induction In Switchgrass

In this study, spikes from eight different switchgrass cultivars of two ecotypes were studied to establish a regeneration system by tissue culture. The difference on regeneration ability was analysed combining with the clustering analysis method and variation coefficient method between different switchgrass cultivars. And two lowland switchgrass cultivars(Alamo and Kanlow) were studies on polyploid induction by colchicines to provide new materials for breeding, development and utilization of switchgrass in future.The main results of this study are as follows:(1) In the study of regeneration system of switchgrass, Alamo performed best with the shortest callus induction starting time, the highest induction rate and differentiation rate of callus. Cave-in-Rock has the highest callus proliferation rate and the longest root length of regeneration seedlings, and Kanlow with the most root number of regeneration seedlings.(2) According to different growth indexes in the regeneration system, the eight switchgrass cultivars are classified into two categories by the method of cluster analysis, one category is Alamo, Kanlow, Cave-in-rock and NewYork, the other is Blackwell, Forestburg, Trailblazer and Pathfinder. The variation method was used to evaluate their different regeneration ability of switchgrass cultivars, which from high to low is Alamo > Cave-in-rock > Kanlow > NewYork > Forestburg > Trailblazer > Blackwell > Pathfinder.(3) Switchgrass callus was treated with different colchicine concentration(0, 0.04%, 0.08% and 0.12%) at different time intervals(24 h, 48 h, 72 h, 96 h) for polyploid induction in this study. And results show it has the highest induction rate with a 0.08% colchicine treatment for 72 h in the dark.(4) Cytological identification and flow cytometry assay were used to determine the ploidy of switchgrass materials in this study. The results show that the leaf stomata number of octaploid is significantly less than that of tetraploid, but the stomatal length and width were significantly higher than that of the tetraploid. And the leaf nuclei relative DNA content of the octaploid, measured by flow cytometry, is two times of the tetraploid.