A Novel Low-Mr Solute Specified In Dune Reed And Its Roles In The Plant Adaptation To The Stress Habitat

It is well documented that environmental or abiotic stresses such as drought, high orlow temperature as well as high salinity have in common their effects on plant water statusand oxidative damage, accompanied by lower photosynthetic rate. On the other hand,almost all the plants often accumulate some metabolites to certain levels in cell inintensifying its anti-abiotic-stress capacity. These stress-induced metabolites, osmolytes orosmoprotectants, usually do not interfere with or have little negative effect on the normalbiochemical metabolic network. Instead, they usually play a multiple role of adjusting cellosmotic potential and maintaining the integration of proteins(enzyme) and biomembraneunder stresses. These metabolites are often termed as compatible solutes. During ourstudy on reeds from different habitat, A small solute was obtained with columnchromatography, which only exists and accumulates in the leaves of dune reed innorthwest China's desert region. The purified compound showed a dark brown, non-crystalappearance and tasted smell-less and a bit astringent. Chemical composition was onlyC(61.9%), H(5.8%), O(18.1%), N(14.2%), with apparent alkalinity and high polarity. Thecompound was soluble in water, lite acid or alkali, and aquatic alcohol but not in commonesters, ketones, benzene or trichloromethane. It has unique polyamine and aromaticfeatures, which are quite different from those known ones accumulated under stresses byplants and has a very strong absorption in UV(213nm) and UV-B(287, 312nm) fields. Wepreliminarily suggest that the solute is a polyamine aromatic compound (PAAC)The natural quantity of the PAAC was strikingly proportional to monthly average airtemperature or monthly maximum temperature as the index of high-temperaturestress(r=0.91, 0.88 respectively, p<0.05). On other hand, the community of DR is farscattered than that of SR, resulting in higher leaf and air temperature at crown due to theradiation and limited water supply as well. So certain causality could be concludedbetween the accumulation of the PAAC and the adaptation of DR to high temperature ofthe habitat.The accumulated PAAC in July could amount to 0.5-0.6mg/g FW, but which could onlyaccount for a concentration of about 1.5mmol/L if it is equally distributed in cells. Thus if...