叠氮化钠诱变对不同大豆种质低温耐受性的影响

Effect of Sodium Azide-induced Mutagenesis on Low-temperature Tolerance of Soybean Germplasms

【目的】利用不同浓度叠氮化钠对3个种质大豆叶芽进行离体诱变,筛选最佳诱导浓度,并对其进行生理生化分析,鉴定诱变后不同种质丛生芽的低温耐受性。【方法】以常蔬特大王、台湾292、剑河大豆叶芽为材料,采用不同质量浓度叠氮化钠(0.4、0.8、1.0 mmol·L-1)进行离体诱导试验,筛选最佳诱导处理;进一步对经最佳诱导处理(0.8 mmol·L-1、48 h)的叶芽进行4℃低温胁迫处理4 d,在低温胁迫前及胁迫期间共5 d中,每天测定其生理生化指标。【结果】0.8 mmol·L-1叠氮化钠处理48 h的死亡率略高于半致死率,为最佳诱导处理。3个种质诱变植株在低温胁迫下的渗透调节物质、光合色素含量均高于对照,种质差异表现为台湾292>常蔬特大王>剑河大豆。常温条件下叠氮化钠诱变能显著提高台湾292、剑河大豆的SOD、CAT活性。3个种质的正常植株在低温胁迫下的抗氧化能力存在差异,剑河大豆(SOD、POD活性提升)>常蔬特大王(POD活性提升)>台湾292(SOD、POD活性略有提升,CAT活性下降)。叠氮化钠诱变对3个种质的低温抗氧化能力提升水平不一样,与对照植株相比,台湾292(POD活性提升,SOD活性略有下降)>常蔬特大王(无显著变化)>剑河大豆(SOD、POD活性下降)。常蔬特大王和台湾292的MDA含量表现为先升高后降低,而剑河大豆一直保持升高趋势,但相对于0 d的MDA含量提高的种质间差异表现为:台湾292>常蔬特大王>剑河大豆。【结论】叠氮化钠诱变可提高3个大豆种质的渗透调节物质、光合色素含量,其中:改良种质常蔬特大王和台湾292提升较多,地方种质剑河大豆提升较少。改良种质台湾292诱变前后及低温处理前后表现较好,抗氧化能力有所提升;常蔬特大王诱变前后及低温处理前后均表现稳定,诱变对其性状改良潜力较小;诱变对未经改良的地方种质剑河大豆抗氧化酶活性改变较大,在常温下为有利变异,在低温下为不利变异。综合以上结论可知,叠氮化钠诱变对不同大豆种质的低温耐受性提升水平存在差异,表现为:台湾292>常蔬特大王>剑河大豆。

【Objective】 By immersing buds in varied concentrations of sodium azide solutions to induce mutagenesis in vitro on 3 soybean germplasms, optimized induction conditions were determined based on the effect on the low-temp tolerance of the mutants under stress.【Methods】 Young buds of Changshutedawang(CSTDW), Taiwan 292, and Jianhe soybean germplasms were immersed in sodium azide solutions of different concentrations for the in vitro mutagenesis induction. After the optimized induction treatment(immersing buds at 0.8 mmol sodium azide/L for 48 h), the plants were subjected to low-temp stress at 4 ℃for 4 d prior to the physio-biochemical determinations.【Results】 The mortality rate of the treated plants was only slightly higher than the median lethal dose(LD50). Under the low-temp stress, the contents of osmosis regulating substance and photosynthetic pigment in the mutant plants were higher than those in control. At room temperature, the increases on the germplasm was in the order of Taiwan 292> CSTDW> Jianhe, and the SOD and CAT in Taiwan 292 and Jianhe were significantly increased. Under low temperature, the antioxidant capacities differed among the germplasms. Overall, Jianhe was higher than CSTDW and followed by Taiwan 292. Specifically, SOD and POD activity increased in Jianhe, POD increased in CSTDW, and SOD and POD slightly increased and CAT decreased in Taiwan 292. Compared to control, Taiwan 292 had the greatest antioxidant activities showing an increased POD and slightly decreased SOD activity, CSTDW was next in line with no significant change, and Jianhe had the least with decreased activities on both SOD and POD. The MDA contents of CSTDW and Taiwan 292 increased initially followed by a decline, while Jianhe maintained an increasing trend. The overall increased levels ranked Taiwan 292> CSTDW> Jianhe. 【Conclusion】 The induced mutagenesis increased the osmosis regulating substance and photosynthetic pigment contents in the 3 soybean germplasms. The improvement on low-temp tolerance was higher for CSTDW and Taiwan 292 but lower for the local Jianhe soybean. After mutagenesis and low-temp treatment, Taiwan292 performed well with a heightened antioxidant capacity. On the other hand, Jianhe changed significantly on the enzymatic activity, the condition was favorable for the plants at room temperature but disadvantageous at low temperatures. In all, the low-temp tolerance of the soybean germplasms generated by sodium azide-induced mutagenesis were found to be Taiwan292>CSTDW>Jianhe.