Effects of Parasitic Plant Cistanche deserticola on Chlorophyll a Fluorescence and Nutrient Accumulation of Host Plant Haloxylon ammodendron in the Taklimakan Desert
2012-06-26
Haloxylon ammodendron, a perennial shrub of family Chenopodiaceae, is mainly distributed in the deserts and semi-deserts of the Northern Hemisphere. H. ammodendron is known as the host of Cistanche deserticola, a perennial parasitic herb of family Orobanchaceae. Because of its own inability to photosynthesis, C. deserticola attaches underground directly to the roots of the dicotyledonous plant H. ammodendron. Growth of C. deserticola depends completely on its host, which provides carbohydrate, minerals, and even water.
Photosynthesis is one of the most important metabolic activities in plants. Photosystem II is thought to be the most sensitive site of inhibition in plants to environmental stress. Recent studies paid more attention to the interaction between C. deserticola and its host. However, effects of the parasitic plant C. deserticola on the photosystem activity of H. ammodendron were little known. Therefore, researchers investigated the effect of C. deserticola infection on photosystem II activity in the host plant H. ammodendron by in vivo chlorophyll a fluorescence technology in the Taklimakan Desert. Furthermore, due to the practice of irrigation with salty water, the status of inorganic ions and nutrient accumulation between the host and non-host plants were also investigated.
The results from field experiments showed that the infection of C. deserticola reduced the non-photochemical quenching of the variable chlorophyll fluorescence (NPQ) and the potential maximum quantum yield for primary photochemistry (Fv/Fm) of the host. Compared with non-host plants, the host H. ammodendron had low nutrient, low inorganic ion contents (Na+ and K+) and low K+/Na+ ratios in the assimilating branches. It suggested that C. deserticola infection reduced the nutrient acquisition and caused damage to the photoprotection through thermal dissipation of the energy of the photosystem II in the host, resulting in a decrease in the tolerance to salinity and high radiation. It was concluded that the attachment of the parasite plant (C. deserticola) had negative effects on the growth of its host.
The result has been published on Journal of Arid Land, 2012, 4(3): 342-348. The paper is also archived at http://jal.xjegi.com/EN/abstract/abstract155.shtml.