ABSTRACT
In this paper, Spiraea fritschiana and Spiraea bunmalba 'Goldmound' were treated with mild, moderate, and severe drought to study the dynamic changes of their photosynthesis capability, and two-dimensional electrophoresis and mass spectrometry were adopted to analyze and identify the differences in the protein expression of the two species before and after the treatments, and the physiological mechanisms inducing the changes of the photosynthesis capability. Drought treatments had significant effects on the photosynthesis capability of the two species. Under drought stress, the maximum photosynthetic rate, light compensation point, and light saturation point decreased gradually, suggesting that the responses of the two species to drought stress were progressive. The two species presented stronger recovery capability after the mild and moderate stresses, but weaker recovery capability after severe stress. After the inducement of drought stress, the weaker drought-resistant S. bunmalba 'Goldmound' had six protein spots lost, eleven new protein spots appeared, thirteen protein spots up-regulation expression, and four protein spots down-regulation expression. All of the proteins were low molecular weight acidic proteins, of which, there were three kinds of different proteins that had been induced expression by drought and were the oxygen-enhanced protein factor 1 and 2 and the degradation fragments of large subunit 1,5-ribulose bisphosphate carboxylase/oxygenase. The drought- resistant difference of the two Spiraea species was related to the changes of their photosynthesis capability during drought stress.
