源于空间诱变的大麦纯合突变体的氮素吸收利用评价

Evaluation of nitrogen uptake and utilization in barley homozygous mutants derived from space mutagenesis

为了挖掘氮素利用率高的大麦种质材料,以大麦(Hordeum vulgare)原始品种‘花30’和空间诱变结合小孢子培养获得的纯合突变体SP30-5为供试材料,在不同氮素水平下,比较其成熟期的农艺性状,同时,在苗期低氮条件下供应不同氮素形态时,对两份材料的氮素吸收利用差异进行比较。结果发现,在成熟期,相比高氮, SP30-5在低氮水平的单株产量、地上部干物重和氮素利用率均显著优于其原始品种‘花30’。在苗期,低氮条件下, SP30-5在三种供氮形式下地上部的干物重和氮素利用率均显著优于原始品种‘花30’,且SP30-5地上部对硝态氮的利用最强,对硝铵态氮和铵态氮两种氮素形态的利用无显著性差异。在硝态氮和硝铵态氮的处理下, SP30-5叶片中的硝酸还原酶和核酮糖-1,5-二磷酸羧化酶活性均显著优于原始品种‘花30’,且在硝态氮处理下, SP30-5叶片中基因HvNR1和HvRbcL的相对表达量显著优于其他处理和‘花30’的基因相对表达量,据此推测该纯合突变体材料在硝态氮供应下地上部氮素利用率的提高可能与叶中的硝酸还原酶和核酮糖-1,5-二磷酸羧化酶活性以及编码基因HvNR1和HvRbcL存在一定的联系,研究结果为解析空间诱变纯合体氮素吸收利用的分子机理提供了线索。

To excavation the barley germplasm material with high nitrogen efficiency, the original variety ‘H30’ and the SP30-5 derived from the spatial mutagenesis combined with microspore culture were used as the test materials. The agronomic characters of the two materials in the mature stage were compared under different nitrogen levels. Meantime, when supplied the different nitrogen forms under low nitrogen condition at seedling stage, the differences of nitrogen absorption and utilization between the two materials were also analyzed. The results showed that the yield per plant, dry matter and NUE in the aboveground of SP30-5 were significantly better than ‘H30’ under low nitrogen condition when compared to the high nitrogen level. In the seedling stage, the dry weight and nitrogen use efficiency of SP30-5 in the aboveground were significantly better than that of the original cultivar ‘H30’ under the three nitrogen supply forms.SP30-5 in the aboveground had the strongest utilization of nitrate nitrogen, while there was no significant difference on utilization rate of ammonium nitrate and ammonium nitrogen between the two materials.Under the NO;-N and NH;NO;conditions, the nitrate reductase and ribulose-1,5-bisphosphate carboxylase activities in leaves of SP30-5 were also significantly better than that of the original variety. Through the study on the gene expression of key enzymes, the expression of HvNR1 and HvRbcL in SP30-5 were significantly higher under the nitrate nitrogen treatment than other treatments as well as in ’H30’. It is speculated that the improvement of aboveground nitrogen utilization rate of SP30-5 under the nitrate nitrogen treatment may be related to the activity of nitrate reductase, ribulose-1,5-bisphosphate carboxylase as well as the encoding genes HvNR1 and HvRbcL. The findings provide clues for the molecular mechanism of nitrogen uptake and utilization in space mutagenesis homozygote lines.