Germplasm Diversity And High-yield Formation Of Helianthus Tuberosus L.

Helianthus tuberosus L.(Asteraceae) is widely cultivated for its perennial tubers as energy resource, food addition, forage production, and garden ornamentations. For food addition, inulin in this plant as a soluble dietary fiber is highly beneficial to our body. The non-food biomass energy is becoming important in the future due to the fact that the fossil fuel is being exhausted and environmental pollution is highly be aggravated. Therefore, further examination of germplasm diversity and genetic improvement of H. tuberosus L. are necessary for its possible wide usages in the future. We collected60accessions of this species from Europe and Asia as our study materials. Genetic diversity of these accessions is firstly assessed by five pairs of AFLPs and17phenotypic characteristics. Then, the high-yield varieties were picked out by comparing the tuber biomass of all accessions and the cultivated ones China. Finally, the underlying mechanisms of these high-yield varieties were further investigated by analyses of the photosynthetic characteristics.The high variations between accessions were recovered by phenotypic characteristics, and AFLP markers. The26%of the AFLP loci are polymorphic and Nei’s gene diversity is0.0751and Shannon’s information index is0.1159. Based on Principal Components Analysis and Cluster Analysis of phenotypic traits, two clades were recovered while three clades were identified based on AFLP polymorphisms. Both phenotypic and AFLP analyses showed a moderate correlations.We found that there is no obvious genetic differentiation between European and Asian accessions (5%). However, genetic differentiations between three AFLP clades were high and phenotypic variations within each molecular clade were also highly variable. Group I was characterized by strong sexual reproduction, high above-ground biomass and tuber nutritions while Group Ⅱ by long vegetation growth. Group Ⅲ had a higher tuber yield and sugar content than the other two groups.Six high-yield varieties were selected through comparing the tuber biomass of the individual clones through all these and control varieties. The total biomass of J115and JN2D from Asia are707.84±40.07g (dry weight/each individual, the same as the following) and631.13±15.75g respectively while those of DK17and DK5from Europe are674.69±11.73and652.16±22.27g, respectively. The growth characteristics of J115, DK5and JN2D were described in details. Subsequently, the characteristic parameters were determined regarding the light and CO2response curves of photosynthesis of three varieties and the results displayed that the high-yield varieties always have lower LCP and CCP, and higher Pmax, AQE and CE. Therefore, our results suggested that the high-yield biomasses of some varieties are correlated with their special photosynthetic characteristics.This study, from germplasm diversity and genetic improvement analyses to high-yield breeding and photosynthetic characteristics of the high-yield varieties, provides a basic procedure for studying H. tuberosus. All results laid a basic frame for further breed improvements in the future.