盐胁迫对花生幼苗离子动态及耐盐基因表达的影响

Effects of salt stress on ion dynamics and the relative expression level of salt tolerance genes in peanut seedlings

不同花生品种的耐盐能力各有差异,本研究以耐盐花生品种花育25 (Huayu 25,HY25)和盐敏感品种花育20(Huayu 20,HY20)为材料,利用非损伤微测技术,测定盐胁迫下花生幼苗根尖中Na^(+)、K^(+)、Ca^(2+)、NH_(4)^(+)、NO_(3)^(–)、Cl^(–)的流速;并同期检测了幼苗的生长性状、主要耐盐基因的表达及渗透调节物质(可溶性糖、脯氨酸)含量的变化,以明确花生的耐盐能力与离子吸收、转运及抗逆调控的关系。结果表明:(1)盐胁迫下Na^(+)内流减弱,外排速率增加,K~+内流提高,但是相对而言,HY25的Na~+外排速率及K~+内流速率均高于HY20,表明HY25通过排Na^(+)保K^(+)提高耐盐性;(2)盐胁迫促进Ca^(2+)迅速内流,并且耐盐品种比盐敏感品种Ca^(2+)内流速率更高,可能与耐盐有关;(3)盐胁迫导致两品种NO_(3)^(–)外排,但耐盐品种HY25的外排流速更低,表明HY25可通过减缓NO_(3)^(–)的流失以抵御盐胁迫的危害;(4)盐胁迫促使耐盐品种HY25 Cl^(–)外排,但盐敏感品种Cl^(–)的内流速率提高,表明HY25可通过加快Cl^(–)的外排减轻Cl^(-)的毒害;(5)盐胁迫显著诱导耐盐品种HY25耐盐相关基因Ah NHX1、Ah HA1、Ah SAMDC1、Ah Lea D的表达,可帮助其提高盐耐受性。综上,HY25的高耐盐能力与较强的离子稳态和较高的耐盐基因表达量密切相关。明确盐胁迫下花生根系的离子流动规律和抗逆机制,将为改善盐碱地花生出苗、立苗、健苗及其调控技术的建立提供理论支撑。

Different peanut varieties have different salt tolerance.In this study,to determine the flow rates of ions Na^(+),K^(+),Ca^(2+),NH_(4)^(+),NO_(3)^(–),and Cl^(–)in root tips of peanut seedlings under salt stress via Non-invasive Micro-test technique,a salt-tolerant peanut variety Huayu 25(HY25)and a salt-sensitive variety Huayu 20(HY20)were used as the experimental materials.The growth traits,the relative expression level of major salt tolerance genes,and the contents of osmotic regulatory substances(soluble sugar and proline)were also measured to establish the difference of ion absorption and stress resistance regulation in different varieties.The results showed as follows:(1)Under NaCl stress,Na+influx was inhibited,and its efflux increased,but promoted the influx of K+.The efflux rate of Na+and influx rate of K^(+)in HY25 were higher than HY20,which may improve salinity tolerance by preserving K+and discharging Na^(+).(2)Salt stress promoted Ca^(2+)influx,and the Ca^(2+)influx rate of salt-tolerant varieties was higher than the salt-sensitive varieties,which might be related to salt tolerance.(3)NO_(3)^(–)exhibited efflux in both varieties under salt stress,but the efflux rate of the salt-tolerant variety HY25 was lower,indicating that HY25 could resist the harm of salt stress by slowing the loss of NO_(3)^(–).(4)Salt stress induced Cl^(–)efflux in HY25 but influx in salt-sensitive variety,indicating that HY25 could reduce the toxicity of Cl^(–)by accelerating the efflux of Cl^(–).(5)Salt stress significantly up-regulated the relative expression level of salt-tolerant genes AhNHX1,AhHA1,AhSAMDC1,and AhLeaD in salt-tolerant variety HY25,which could help improve its salt tolerance.Clarifying the dynamic changes of root ion flow and resistance mechanism under salt stress can provide the theoretical support for improving the emergence,establishment,and development of peanut seedlings in saline-alkali land and the establishment of regulation technology.