Li Xiaolong, Shi Shangli, Zhang Xiaoyan, Li Changning, Wang Huning, Kang Wenjuan, Yin Guoli
Key Laboratory of Grassland Ecosytem (Ministry of Education), College of Grassland Science, Gansu Agricultural University, Lanzhou 730070, China.
Centers for Grazing Land Ecosystem Sustainability, Gansu Agricultural University, Lanzhou 730070, China.
Life (Basel). 2022 Dec 19;12(12):2140. doi: 10.3390/life12122140.
The allelopathic theory has garnered considerable attention in the field of agricultural production for its efficient plant protection, rapid crop yield increase, and scientific establishment of the crop rotation system. To study the effects of the main maize allelochemical DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) on the growth and development of alfalfa under autotoxic coumarin stress, we treated alfalfa seedlings with DIMBOA under coumarin stress and non-stress conditions in this study. Results show that 0.0342 mM coumarin significantly inhibited alfalfa seed germination percentage(Gp), germination potential(GP), radicle length, germ length, seeding height, and simple viability index (SVI), with decreases of 37.29%, 59.91%, 7.60%, 30.90%, 13.27%, and 45.70%, respectively. An amount of 0.6 mM DIMBOA could promote alfalfa seed Gp, GP, radicle length, germ length, seeding height, dry fresh ratio, and SVI, with increases of 12.38%, 23.91%, 48.69%, 48.65%, 48.68%, 295.12%, and 67.17%, respectively. However, the addition of DIMBOA under conditions of coumarin stress could effectively alleviate coumarin effects on alfalfa seedlings. Coumarin + DIMBOA treatment for 24 h mainly decreased reactive oxygen species (ROSs) and malondialdehyde (MDA) as well as soluble protein and soluble sugar, increasing some antioxidant enzyme activities and antioxidant content to alleviate the oxidative damage of alfalfa caused by coumarin stress. Administration of treatment for 72 h significantly promoted the morphological development of alfalfa seeding roots. Administration of treatment for 96 h significantly enhanced the photosynthetic capacity of alfalfa seedlings. The results of principal component analysis demonstrated that chlorophyll b(Chl b)and net photosynthetic rate() were the key indicators for coumarin + DIMBOA treatment to promote photosynthesis in alfalfa seedlings. Additionally, root length, mean root diameter, and root volume were the key indicators of root growth and development. Coumarin + DIMBOA treatment primarily increased catalase(CAT), peroxidase (POD), and ascorbate peroxidase (APX) activity and antioxidants(ASA) while reducing MDA and superoxide anion radical(O). This study strongly suggested that DIMBOA can effectively improve the tolerance of alfalfa seedlings to coumarin stress through a combination of effects on root morphology, photosynthesis, and physiological indicators.
化感作用理论因其在植物保护方面的高效性、作物产量的快速增加以及作物轮作系统的科学建立，在农业生产领域受到了广泛关注。为了研究主要玉米化感物质2,4 - 二羟基 - 7 - 甲氧基 - 1,4 - 苯并恶嗪 - 3 - 酮（DIMBOA）在自毒香豆素胁迫下对苜蓿生长发育的影响，本研究在香豆素胁迫和非胁迫条件下用DIMBOA处理苜蓿幼苗。结果表明，0.0342 mM香豆素显著抑制苜蓿种子发芽率（Gp）、发芽势（GP）、胚根长度、胚芽长度、幼苗高度和简单活力指数（SVI），分别降低了37.29%、59.91%、7.60%、30.90%、13.27%和45.70%。0.6 mM DIMBOA可促进苜蓿种子的Gp、GP、胚根长度、胚芽长度、幼苗高度、干鲜比和SVI，分别增加了12.38%、23.91%、48.69%、48.65%、48.68%、295.12%和67.17%。然而，在香豆素胁迫条件下添加DIMBOA可有效减轻香豆素对苜蓿幼苗的影响。香豆素 + DIMBOA处理24小时主要降低了活性氧（ROS）和丙二醛（MDA）以及可溶性蛋白和可溶性糖，增加了一些抗氧化酶活性和抗氧化剂含量，以减轻香豆素胁迫对苜蓿造成的氧化损伤。处理72小时显著促进了苜蓿幼苗根系的形态发育。处理96小时显著提高了苜蓿幼苗的光合能力。主成分分析结果表明，叶绿素b（Chl b）和净光合速率（ ）是香豆素 + DIMBOA处理促进苜蓿幼苗光合作用的关键指标。此外，根长、平均根直径和根体积是根系生长发育的关键指标。香豆素 + DIMBOA处理主要增加了过氧化氢酶（CAT）、过氧化物酶（POD）和抗坏血酸过氧化物酶（APX）活性以及抗氧化剂（ASA），同时降低了MDA和超氧阴离子自由基（O）。本研究强烈表明，DIMBOA可通过对根系形态、光合作用和生理指标的综合作用，有效提高苜蓿幼苗对香豆素胁迫的耐受性。
