The Development Of Artificial Polyploid In Miscanthus Lutarioriparius And Its Identification Technique

Miscanthus lutarioriparius (Poaceae) is a Miscanthus species special to China, mainly distributed in the middle and lower branches of the Yangtze River. This species has some elite characters, including robust rhizomes, easy propagation, quick growth, high biomass yield and good fiber quality. The biomass of M. lutarioriparius was used as an important raw material for paper-making or board manufacturing. In recent years, this species was also regarded as an excellent energy crop. Compared to diploids. the polyploidies usually possess bigger vegetative organs, the earlier aging, and higher stress tolerant capacities. In this study, the artificial polyploidy doubling methods as well as rapid polyploidy identification techniques for M. lutarioriparius were established with the colchicine as the chemical inducer. The main results are as follows:1. The selection of genotypes with high frequent callus induction and plant regeneration. The immature inflorescences and the seeds of different genotypes of M. lutaroriparius were used as the explants of in vitro tissue culture. The embryonic callus induction rate from the immature inflorescence explants ranged between 34.4% and 97.5% for eight genotypes, and their plant differentiation rate was from 7.0%to 91.8%. Of those, the A4 genotype was with the highest callus induction rate and plant differentiation rate,97.5% and 91.8% respectively, and the A6 genotype was the second. On the other hand, the genotype A8 gave the highest seed germination and callus induction rate,94.33% and 93.33% respectively.2. Comparasion of different methods of artificial chromosome doubling in M. lutarioriparius. For calli from immature inflorescences as the starting material, the treatment with a colchicine concentration of 0.15% and a soaking duration of 48 h produced a polyploidy induction rate as high as 16%. No polyploidy was induced from the seed calli under all treatment conditions. However, the highest polyploid induction rate up to 13.4% was obtained when the seeds as the starting material using the treatment combination of a seed pre-culture duration of 12 h, a chemical induction with 0.1% colchicine adding 0.1% Tween for 36 h, then a ultrasonic treatment for 5 min, and finally a vacuum treatment for 5 min.3. Development of rapid polyploidy identification method for M. lutarioriparus. Firstly, a preliminary screening for induced plants by morphology gave birth to 397 young plants. Then, a total of 24 autotetraploid plants were identified from those individuals using a flow cytometry analysis. the chromosome numbers of these autotetraploids were further confirmed by the conventional pressing plate method.