Induction And Evaluation Of Drought Resistance Of Tetraploid Black Locust (Robinia Pseudoacacia L.)

The tetraploid Robinia pseudoacacia L.has the advantages of high stress resistance and wide site adaptability.It has a greater potential for selection and breeding of drought-resistance varieties,and it can alleviate the increasingly serious ecological problems caused by drought in northwest of China.In this study,the three semi-sib families black locust seed Qingshui No.16,No.26 and No.28 from Gansu were used as the materials,and induced by the colchicine of three concentration:30 mg/L,40 mg/L,and 50 mg/L.This experiment tried to explore and improve the artificial inducing system and preliminary ploidy identification method of polyploidy black locust with high efficiency,and studied the drought resistance ability of the resulting tetraploid plants in two environments of tissue culture and potted plants.This study explored the effects of drought stress on the growth and development of tetraploid black locust from three half-sib families under the three stages of regeneration,rooting and vegetative growth period after transplanting.Comprehensive evaluation of the drought resistance performance of tetraploid Robinia pseudoacacia and induction and preliminary screening of excellent tetraploid Robinia pseudoacacia plants with drought resistance have been get.The main findings are as follows:(1)A polyploidy black locust plantlet was induced by a solution impregnation with colchicine solution,and the mutant seedlings were subjected to continuous ploidy detection during multiple subcultures by flow cytometry to investigate the mutant seedlings ploidy change in the process of subsistence.Treating black locust seeds with a concentration of 40 mg/L colchicine solution for 2 days resulted in the highest polyploidy efficiency,and the survival rate and the survival rate of the surviving seedlings were 70.4%and 49.06%,respectively.In the mutagenic seedlings,68.3%of the plants were directly germinated,of which the chimeras accounted for 28.1%;the root organ regenerated plants accounted for 31.7%,of which the chimeras accounted for approximately 5.1%.Plant ploidy tended to stabilize after substituting the cycle for 30 days.Compared with the diploid,the tetraploid plants had the characteristics of increased leaf area,reduced leaf shape index,and increased number of chloroplasts.(2)In the PEG-simulated drought stress test,when the PEG concentration was more than 5%.the leaf regeneration and rooting ability of the black locust plantlets were significantly inhibited.When the PEG concentration reached 15%,the inhibition was more thorough.The survival rate of explants and tissue culture seedlings has been severely affected.The comprehensive evaluation of the resistance performance of tetraploid Robinia pseudoacacia tissue culture seedlings under different concentrations of PEG simulated drought conditions was performed.When the PEG concentration was 5%,the comprehensive performance differences of the tetraploid Robinia pseudoacacia seedlings of the three half-sib families were different.Not significant,when the PEG concentration was 10%and 15%,the drought resistance performance of the tetraploid population induced by No.26 and No.28 seeds had significant advantages compared to No.16 and No.26 under the condition of tissue culture.Of which the differentiation and rooting process has the best performance of drought resistance.(3)Under potting conditions,tetraploid Robinia pseudoacacia showed higher leaf water use efficiency and accumulation of growth compared to the traditional diploid plants,and soluble protein in the leaves of tetraploid at whatever level of moisture was higher than that of the diploid.In the process of severe drought to rehydration,the variation of malondialdehyde content and proline content in the tetraploid Robinia pseudoacacia was also lower than that of the diploid.Compared with diploids,they have better recovery ability under drought conditions,which is an active expression of long-term drought stress,and only the varieties with stronger drought resistance have such characteristics.Among the three sources of tetraploid Robinia pseudoacacia,the integrated drought resistance of the tetraploid Robinia pseudoacacia No.26 was the most prominent.This performance was basically consistent with the in vitro differentiation and the artificially simulated drought stress at the rooting stage.