| Sweet alyssum is one of Cruciferae flowers, which belong to Lobularia,and the plants are dwarf and multi-branched. Sweet alyssum is a fine flower for rock garden layout, and also be used as potted plants, and so onMoreover, it has good adsorption to heavy metal Ni.Until now, few researches about tissue culture andpolyploidy induction of sweet alyssum have reported.. In this study, we used the seeds of sweet alyssum as explants in tissue culture for rapid propagation. At the same time, we used the seeds of sweet alyssum and stems of tissue culture seedling which treated by colchicine for polyploidy induction, and obtained tetraploid of sweet alyssum, we compared the morphological characteristics and resistance to heavy metals Ni between tetraploid and diploid plants of sweet alyssum. These results made a foundation for ploidy breeding and provided a reference for the repaired ecological environment of sweet alyssum.1、The results in vitro regeneration of sweet alyssum showed:The seeds were dipped in the scour3-4hour by water, then sterilized60seconds by75%alcohol and8min by10%HgCl2, survival rate was86.7%, and no pollution. The appropriate medium for inducing buds from leaves and stems was MS+1mg/L6-BA+0.lmg/L NAA, Stem callus induction rate was100%, and the bud differentiation rate was90.0%. Leaf callus induction rate was100%, and the bud differentiation rate was73.3%. The best of multiplication medium for sweet alyssum was MS+0.5mg/L6-BA+0.05mg/L NAA, multiplication coefficient reached6.57, and the buds were many and strong, shoots up to about7cm, and have no callus produced. The best rooting medium was1/2MS +0.5mg/L IBA. The taproot is long and strong, and there are also many of the fibrous roots. The plants are growing well and the color is dark green. The surviving rate of plantlets was80.0%after transplanted to the ground.2、explored technique of the root tip chromosome in sweet alyssum. The results showed that the optimal sampling time of roots was30hour after seed gemiination, using8-hydroxyquinoline solution for the pretreatment, after pretreatment3h, with3%cellulase and0.3%pectinase mixture, for1.5-2hour, stained with Giemsa for the dye8-10min, which was a better way to accumulate of metaphase cells disperse chromosomes, then observe and count chromosomes.3、The inducing tetraploid of the sweet alyssum adapted two methods:Marinating and composite culture. The result show:It was the most effectively induced by immersing seeds of sweet alyssum in0.2%colchicine solution for36h, The inductive frequency was26.7%, tetraploid plants (2n=4x=48) is3.3%.stems of sweet alyssum were incoculated in the medium contained0.3%colchicine for15days, the inductive frequency was22.0%, and tetraploid plants is4.0%.4、Compared characteristics of diploid and tetraploid:(1) Compared external morphology between diploid and tetraploid. The results indicated that the tetraploid plants were grown stronger, which has thicker stems, darker green leaves; length of the blade is less than the diploid plants, while width and thickness larger than diploid plants. The leaves length, width and thickness of tetraploid were76.1%、124.5%、155.0%of diploid respectively, the leaves index was105.4%of diploid.(2) The charaeteristics of stoma and guard cell in tetraploids and diploids were compared. The tetraploids of sweet alyssum with fewer stoma densities were66.9%of those of the diploids, with bigger guard cells. The guard cell length and diameter of tetraploids were113.9%and111.2%of those of the diploids respectively. Chlorophyll contents of teraploid leaves increased which was119.6%of diploid.(3) Compared adsorption of heavy metals Ni2+in diploid and tetraploid. The results showed that When the adsorption time is80min, the diploid and tetraploid absorped capacities for nickel ion were10.30mg/g and14.72mg/g. Tetraploid plants for Ni2+adsorption capacity increased4.42mg/g than that of diploid plants. |
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