Department of Biochemistry, State University of Maringa, Brazil.
Center of Biological Sciences and Nature, Federal University of Acre, Rio Branco, Brazil.
Plant Physiol Biochem. 2021 Sep;166:857-873. doi: 10.1016/j.plaphy.2021.06.040. Epub 2021 Jun 29.
Urochloa ruziziensis, a cover plant used in no-till systems, can suppress weeds in the field through their chemical compounds, but the mode of action of these compounds is still unknown. The present study aimed to investigate the effects of a saponin-rich butanolic extract from U. ruziziensis straw (BfUr) and one of its components, protodioscin on an eudicot Ipomoea grandifolia and a monocot Digitaria insularis weed. The anatomy and the morphology of the root systems and several parameters related to energy metabolism and antioxidant defense systems were examined. The IC values for the root growth inhibition by BfUr were 108 μg mL in D. insularis and 230 μg mL in I. grandifolia. The corresponding values for protodioscin were 34 μg mL and 54 μg mL. I. grandifolia exhibited higher ROS-induced peroxidative damage in its roots compared with D. insularis. In the roots of both weeds, the BfUr and protodioscin induced a reduction in the meristematic and elongation zones with a precocious appearance of lateral roots, particularly in I. grandifolia. The roots also exhibited features of advanced cell differentiation in the vascular cylinder. These alterations were similar to stress-induced morphogenic responses (SIMRs), which are plant adaptive strategies to survive in the presence of toxicants. At concentrations above their IC values, the BfUr or protodioscin strongly inhibited the development of both weeds. Such findings demonstrated that U. ruziziensis mulches may contribute to the use of natural and renewable weed control tools.
鲁兹西亚狗尾草是免耕系统中使用的覆盖植物，它可以通过其化合物抑制田间杂草，但这些化合物的作用方式仍不清楚。本研究旨在研究鲁兹西亚狗尾草秸秆中富含皂素的丁醇提取物（BfUr）及其成分之一原薯蓣皂苷对双子叶植物大花牵牛和单子叶狗尾草杂草的影响。检查了根系的解剖结构和形态以及与能量代谢和抗氧化防御系统相关的几个参数。BfUr 对狗尾草根生长的抑制 IC 值为 108μg mL，对大花牵牛的抑制 IC 值为 230μg mL。原薯蓣皂苷的相应值分别为 34μg mL 和 54μg mL。与狗尾草相比，大花牵牛的根中 ROS 诱导的过氧化损伤更高。在两种杂草的根中，BfUr 和原薯蓣皂苷均导致分生区和伸长区减少，并且侧根提前出现，尤其是在大花牵牛中。根中的维管束也表现出细胞分化的特征。这些变化类似于应激诱导形态发生反应（SIMRs），这是植物在存在毒物时生存的适应性策略。在高于其 IC 值的浓度下，BfUr 或原薯蓣皂苷强烈抑制两种杂草的生长。这些发现表明，鲁兹西亚狗尾草覆盖物可能有助于使用天然和可再生的杂草控制工具。
