| Maize rough dwarf disease (MRDD) caused by the rice black-streaked dwarf virus (RBSDV), a planthopper transmitted virus disease, is one of the most destructive diseases on maize in China, especially it is has frequently been outbreak on the interplanting, late-spring planting or early-summer planting maize in the Huang, Huai, and Hai rivers velley for the last a few years.In this study, laboratory reared planthopper Laodelphax striatellus Fallen on rice was transferred on rice that was infected by rice black-streaked dwarf virus (RBSDV) after circulative period to get the vector with RBSDV. Identification of RBSDV was performed by special DNA fragments 510bp based on RT-PCR with RBSDV species specific primers.Reference to Di pad level approach, with the rice black-streaked dwarf virus vecter (Laodelphax striatellus Fallen) feeding in the 2 leaves stage of Zheng 958 maize, After 15d, we obtain infected RBSDV maize. Molecular characterization indicates that the maize was infected rice black-streaked virus.Pathogenic process of maize rougf dwarf diease (MRDD) was divided into four stages base on the symptom on the plants, i.e. early perceptible stage, developing stage, distinct stage, completely appearent stage. The quantitfication of endogenous hormones, including the gibberellins (GA), indole-3-acetic acid (IAA), abscisic acid (ABA) and zeatin riboside (ZR) in young shoot tip tissue of maize Zhengdan 958 were done by ELISA method. In the infecting process of RBSDV, the contents of IAA decreased gradually and they were 128.00 ng/g fw,114.20ng/g fw,113.27ng/g fw, 108.75ng/g fw at the four stages of the sympts in the infected plants, respectively, with a decrease of 27.6%,28.0%,32.3%,33.5% compared to the control. The ZR content was only significantly lower than that of healthy plants at the symptom developing stage with a decrease of 34.4% to control. The levels of GA contents in the healthy maize plants were decreased as long with the plant developments. However, the contents of GA were increased at the symptom early perceptible stage and developing stage, then decreased. It was significantly increased to 39.5% compared to the control at the symptom early perceptible stage. In contrast with GA, ABA levels of RBSDV infested plants firstly decreased and then increased. However, they all were lower than that of healthy plants throughout the infection process, and were significantly decreased by 59.6,72.1, and 49.0% campared to the control at the symptom early perceptible, developing, and completely appearent stages.These results suggest that the infection of RBSDV on maize upset the balances of endogenous hormones, which stunts the plant development, i.e. causeing rough dwarf. of the increase of IAA and decrease of ZR were resulted in the value of C/A increased, which lead to the loss of apical dominance, slow elongation, horizontal growth (rough dwarf), and even leaf could not be extended. In addition, the decreased IAA would interfere the normal cell differentiation. The contents of GA and ABA were negatively correlated significantly. The unusual decrease of ABA interferes in the maize plant resistance to the RBSDV, the virus are significantly regenerated. In addition, the increase of GA in the plants accelerates the development of unsual differentiated cells of leaf vein and stem, which resulted in the symptom rough dwarf appearance.
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