| Seashore paspalum (Paspalum vaginatium Sw.) originated from the America, is well known as the most powerful salt-tolerant lawn grasses to date. Since diploid germplasm is self-incompatible, and viable seed can not be obtained between different species within the same genus, or seed germination rate is extremely low, etc., the progress of conventional breeding was slow. Colchicine as a chemical mutagen, can both induce polyploidy and gene mutation; therefore, it is widely used in plant breeding program.Comparison of botany properties and stomatal characteristics of leaf epidermis, chromosome identification, and RAPD analysis between self-seeded somatic cell mutant SP2008-3and Adalayd (ck) in Seashore paspalum were carried out; Salt tolerance of mutant SP2008-3was evaluated; And effects of different colchicine concentrations and treated time on callus cell nuclear mass ratio, nuclear abnormal rate, callus browning rate, green sprouts and green plantlet differentiation rates were studied. The major results were as follows:(1) In SP2008-3, stolons internodes length and stem diameter in SP2008-3were respectively reduced34.77%and11.76%(P<0.05); length and width of leaf were separately increased22.55%and11.11%(P<0.05), and there were no significantly differences in erect stem internodes length and diameter compared with Adalayd. In upper leaf epidermis of mutant SP2008-3, stoma density was increased20.58%(P<0.05), and stomatal length and width was respectively reduced9.64%and6.31%(P<0.05); in lower leaf epidermis of SP2008-3. Stoma density was increased40.62%(P<0.05), and stomatal length and width were respectively reduced6.73%and5.33%(P<0.05) in comparison with those in Adalayd. RAPD analysis presents there were differences in DNA because mutant SP2008-3was no missing1100bp band when DNA was amplified by S369.(2) After42d under different salt stresses, there was no significantly different in SP2008-3leaf length compared with0g/L (ck) sea salt, and leaf length in Adalayd was also no significant differences except that leaf length is significant shorter under34g/L sea salt concentration compared with that under ck treatment. Leaf width in SP2008-3under sea salt treatments was narrower than that under no sea salt (P<0.05), and the same results in Adalayd except no significant differences under13.6g/L sea salt compared with ck treatment. Stolon internode length and diameter in SP2008-3were less than those under ck treatment (P<0.05); stolon internode length of Adalayd was shorter than that under ck treatment (P<0.05). Changes of Adalayd stolon diameter first decreased then increased and further declined. Stolon diameter in Adalayd was significantly smaller than that under no sea salt; nevertheless, stolon diameter in Adalayd under13.6g/L and20.4g/L salt concentrations was not significantly different compared with that under ck treatment.Leaf length, leaf width, stolon internode and diameter in SP2008-3were less than those in Adalayd only in salt concentration of13.6g/L (P<0.05). In the rest of salt concentrations, there were no significant difference between SP2008-3and Adalayd; Under each salt concentration, there was no significant difference between SP2008-3and Adalayd root dry weight; When the salt concentration≤6.8g/L, SP2008-3stem dry weight, leaf dry weight were less than Adalayd (P<0.05); When the salt concentration≥13.6g/L, there was no significant difference in each part of the biomass between SP2008-3and Adalayd; Changes of Root-shoot ratio showed that the response of salt stress of aboveground parts were more sensitive than root parts both in SP2008-3and Adalayd.(3) Under the same disposed time, callus nuclear mass ratio under different colchicine concentrations were different (P<0.05). when disposed time was Id, colchicine concentration was500mg/L and1000mg/L, callus nuclear mass ratio was greater than that under0mg/L (ck)(P<0.05), and there was significant difference between treatments; With the increase of colchicine concentration, callus nuclear mass ratio was smaller than ck treatment (P<0.05). Abnormal rate of callus nuclei had increase at a certain extent with the increase of colchicine concentrations. Under the same colchicine concentration, callus nuclear mass ratio smaller than ck treatment (P<0.05) or similar with ck treatment (P>0.05) with the increase of disposed time; Changes of abnormal rate of callus nuclei in each disposed time were different.Callus browning rate was increasing with the increases of colchincine concentration and disposed time (P<0.05). Colchincine concentration of500mg/L combined with disposed time of1d,3d,5d,7d treatment,1000～3000mg/L colchincine concentration combined with1d treatment, the callus browning rate was11%～33%. Colchincine concentration4000mg/L combined with1d,3d,5d,7d treatment, the callus browning rate was59%～88%. Effects of different colchicine concentrations and disposed time on the callus green shoots, green plantlet differentiation rates were different. Compared with ck treatment, colchincine concentration of500～2000mg/L combined with1d treatment, the callus green shoots differentiation rates were7%-10%. Colchincine concentration of3000mg/L combined with1d,3d,5d treatment, the callus green shoots differentiation rates were27%～58%. Colchincine concentration of500mg/L combined with1d,3d,5d treatment and colchincine concentration of1000～2000mg/L combined with Id treatment, callus green plantlet differentiation rates were50%～72%. When colchicine concentrations were3000mg/L and4000mg/L, the green plant differentiation rates of each diposed time were correspondly reduced(P<0.05). |
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