玉米种子发芽生理和抗氧化系统对砷胁迫响应的基因型差异及其机制研究

Genotypic Differences of Arsenic Stress in Germination Physiology and Antioxidant System of Maize Seeds

为探究不同基因型玉米品种对砷胁迫的响应差异性,本研究采用营养液培养试验,研究了砷胁迫下20个玉米品种的发芽势、发芽率、根长、株高、干重、地上部及根部砷含量、抗氧化酶活性、抗氧化非酶物质含量及基因表达等指标变化,评价了不同基因型品种的耐砷性。结果表明,与对照(CK)相比,砷处理条件下,玉米各测定指标表现出明显的差异性,其中发芽势、发芽率、根长、株高、干重的处理/CK比率范围分别是0.58~1.18、0.61~1.18、0.49~1.04、0.72~1.12、0.55~2.83,各品种玉米的砷转运系数为0.02~0.07。利用12个指标进行主成分分析和聚类分析,筛选出2个砷耐受型品种,5个砷敏感型品种,其中康农玉999为最耐受型品种,三北89为最敏感型品种。进一步对康农玉999和三北89进行抗氧化系统分析,发现砷处理下康农玉999的过氧化氢酶(CAT)、过氧化物酶(POD)活性均略低于CK,且超氧化物歧化酶(SOD)活性下降幅度较大,相比于CK降低79%,而丙二醛(MDA)、谷胱甘肽(GSH)、抗坏血酸(AsA)含量均高于CK;三北89的SOD、CAT、POD活性和GSH、AsA含量均高于CK,MDA含量相比于CK降低50%。对2个品种进行基因表达分析,结果显示,与康农玉999相比,检测出的5个与植物抗砷性相关转录本中,三北89有4个抗砷相关转录本表达量明显上升,只有1个ArsB相关转录本表达量略降低。综上可知,砷胁迫下不同基因型玉米种子的生长和生理参数以及相关基因表达均表现出明显的差异性。本研究结果为砷污染土壤进行玉米的农业生产种植提供了理论依据。

In order to explore the response differences of different maize genotypes to arsenic stress, the seeds of 20 maize cultivars were germinated under As stress to understand the response of genotypic differences by measuring germination potential, germination rate, root length, shoot length, dry weight, arsenic content in shoot and root, antioxidant enzyme activity, and antioxidant non-enzymatic substances as well as gene expression. Compared with CK, the indices under arsenic stress showed obvious diversity. The range of treatments/CK ratio germination potential, germination rate, root length,shoot length,dry weight and arsenic transport coefficient of each variety maize seeds were 0.58~1.18, 0.61~1.18, 0.49~1.04, 0.72~1.12, 0.55~2.83 and 0.02~0.07, respectively. Principal component analysis and cluster analysis were carried out with 12 indicators, and two tolerant and five sensitive cultivars were thus selected, among which Kangnongyu 999 was the most tolerant variety and Sanbei 89 was the most sensitive variety. Assay of the antioxidant system of Kangnongyu 999 and Sanbei 89 showed that the activities of CAT and POD of Kangnongyu 999 treated with arsenic were less than those of the CK. The activities of SOD were only 0.21 times of those of the CK, and the contents of MDA, GSH and ASA were all higher than those of the CK. The activities of SOD, CAT and POD of Sanbei 89 treated with arsenic were higher than those of CK, the contents of GSH and ASA were higher than those of CK, and the content of MDA was 50% lower than that of CK. Gene expression analysis of two varieties showed that compared with Kangnongyu 999, four of the five arsenic-resistant transcripts expression level detected in Sanbei 89 increased significantly. The results showed that germination potential, germination rate, root length, stem length, dry weight, arsenic transport coefficient, antioxidant enzyme activity and antioxidant non-enzymatic substance content of maize genotypes were significantly different under arsenic stress. The results provide a theoretical basis for the agricultural production of Maize in arsenic-contaminated soil.