Regulation of Root Length and Lateral Root Number in Trifoliate Orange Applied by Peroxide Hydrogen and Arbuscular Mycorrhizal Fungi

oleh: Chun-Yan LIU, Yong-Ming HUANG, Ying-Ning ZOU, Qiang-Sheng WU

Format: Article
Diterbitkan: AcademicPres 2014-06-01

Deskripsi

Root system morphology (RSM) in plants plays a key role in acquiring nutrients from the soil and is also altered by abiotic or biotic factors including soil microorganisms and signal molecules. The present study was made to evaluate the effects of an arbuscular mycorrhizal fungus (AMF, <i>Glomus versiforme</i>) and exogenous peroxide hydrogen (H<sub>2</sub>O<sub>2</sub>, 0, 1 and 100 &#956;M) on root length, lateral root number and activities of polyamine-metabolized enzymes in trifoliate orange (<i>Poncirus trifoliata</i>) seedlings. After 5 months of inoculation with AMF, root mycorrhizal colonization was significantly increased by application of 1 &#956;M H<sub>2</sub>O<sub>2</sub>, but markedly restrained by 100 &#956;M H<sub>2</sub>O<sub>2.</sub> Inoculation with AMF significantly increased the taproot length and the number of second- and third-order lateral roots under 1 and 100 &#956;M H<sub>2</sub>O<sub>2</sub><sup></sup>application. The AMF infection significantly increased 0-1 cm classed root length and total root length, regardless of H<sub>2</sub>O<sub>2</sub> concentration. In general, inoculation with AMF increased arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) activity of roots under 0, 1 and 100 &#956;M H<sub>2</sub>O<sub>2</sub>, increased diamine oxidase (DAO) activity of roots under 0 &#956;M H<sub>2</sub>O<sub>2</sub> and decreased DAO activity of roots under 1 and 100 &#956;M H<sub>2</sub>O<sub>2</sub>. Root polyamine oxidase (PAO) activity was similar between AMF and non-AMF seedlings, irrespectively of H<sub>2</sub>O<sub>2</sub>concentration. Results suggest that lower concentration of H<sub>2</sub>O<sub>2</sub>(1 &#956;M) might be regarded as a signal to stimulate mycorrhizal and lateral root development through increase of ADC and ODC and decrease of DAO, while high concentration of <sub>2</sub>O<sub>2</sub> (100 &#956;M) as a toxic compound of reactive oxygen species restricted AMF colonization.