Ma Chao, Ban Tiantian, Yu Hongjun, Li Qiang, Li Xiaohui, Jiang Weijie, Xie Jianming
College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China.
Institute of Horticulture, Guizhou Academy of Agricultural Science, Guiyang 550006, China.
Plants (Basel). 2023 Jun 7;12(12):2243. doi: 10.3390/plants12122243.
Nitrate nitrogen (NO-N) is widely used in the cultivation of the cucumber ( L.). In fact, in mixed nitrogen forms, partially substituting NO-N with NH-N can promote the absorption and utilization of nitrogen. However, is this still the case when the cucumber seedling is vulnerable to the suboptimal-temperature stress? It remains unclear as to how the uptake and metabolism of ammonium affect the suboptimal-temperature tolerance in cucumber seedlings. In this study, cucumber seedlings were grown under suboptimal temperatures at five ammonium ratios (0NH, 25%NH, 50%NH, 75%NH, 100%NH) for 14 days. Firstly, increasing ammonium to 50% promoted the growth and root activity and increased protein and proline contents but decreased MDA content in cucumber seedlings. This indicated that increasing ammonium to 50% enhanced the suboptimal-temperature tolerance of cucumber seedlings. Furthermore, increasing ammonium to 50% up-regulated the expression of the nitrogen uptake-transport genes , and , which promoted the uptake and transport of nitrogen, as well as the up-regulation of the expression of the glutamate cycle genes , , , and , which promoted the metabolism of nitrogen. Meanwhile, increased ammonium up-regulated the expression of the PM H-ATP genes and in roots, which maintained nitrogen transport and membranes at a suboptimal temperature. In addition, 13 of 16 genes detected in the study were preferentially expressed in the roots in the increasing ammonium treatments under suboptimal temperatures, which, thus, promoted nitrogen assimilation in roots to the enhance the suboptimal-temperature tolerance of cucumber seedlings.
硝态氮（NO-N）在黄瓜（L.）栽培中被广泛使用。事实上，在混合氮形态中，用NH-N部分替代NO-N可促进氮的吸收和利用。然而，当黄瓜幼苗易受亚适温胁迫时情况是否依然如此？目前尚不清楚铵的吸收和代谢如何影响黄瓜幼苗的亚适温耐受性。在本研究中，黄瓜幼苗在亚适温下以五种铵比例（0NH、25%NH、50%NH、75%NH、100%NH）生长14天。首先，将铵含量增加到50%可促进黄瓜幼苗的生长和根系活性，增加蛋白质和脯氨酸含量，但降低丙二醛含量。这表明将铵含量增加到50%可增强黄瓜幼苗的亚适温耐受性。此外，将铵含量增加到50%可上调氮吸收转运基因、和的表达，促进氮的吸收和转运，同时上调谷氨酸循环基因、、、和的表达以促进氮的代谢。同时，铵含量增加上调了根系中质膜H-ATP基因和的表达，在亚适温下维持氮转运和膜的稳定性。此外，本研究中检测的16个基因中有13个在亚适温下铵含量增加处理的根系中优先表达，从而促进根系中的氮同化以增强黄瓜幼苗的亚适温耐受性。
