Document Type: Research Paper
Plant Introduction & Quarantine and Plant Product Key Laboratory of Xiamen City, Xiamen Overseas Chinese Subtropical Plant Introduction Garden
Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University
Fujian Key Laboratory of Physiology and Biochemistry for Subtropical Plant, Fujian Institute of Subtropical Botany
Background: Salinity is a major environmental limiting factor, which affect agricultural production. The two Manilkara seedlings (M. roxburghiana and M. zapota) which have high economic which could not adapt well to higher soil salinity and little is known about their proteomic mechanisms.
Objectives: The mechanisms responsible for the effects of salinity on the two M. species leaves were examined by means of proteomic analysis.
Materials and Methods: The seedlings were cultivated in a greenhouse and treated with NaCl. Leaves of control and the salt-stressed seedlings were sampled for phenol protein extraction. Proteins were separated by two-dimensional gel electrophoresis coupled with mass spectroscopy to study the change of proteins under different NaCl concentration.
Results: For M. roxburghiana leaves, 21 protein spots exhibited significant abundance variations between the control and the 6‰, 8‰ NaCl treatments, of these 13 proteins were identified. They included L-ascorbate peroxidase, chloroplast carbonic anhydrase, phosphoglycerate kinase, 5 heat-shock proteins(HSPs) which were all down-regulated; For M. zapota leaves, 35 protein spots exhibited significant abundance variations, then 24 proteins were identified, including 7 down-regulated HSPs as well as glyceraldehyde-3-phosphate dehydrogenase, Cell division protein, putative mitochondrial NAD-dependent malate dehydrogenase, ATP synthase, Rubisco large subunit-binding protein, Cytochrome c peroxidase.
Conclusions: Based on the common identified proteins between the two M. species, our results indicated that the identificated proteins in the two M. species were involved in carbohydrate metabolism, photosynthesis, defense and stress. HSPs exhibited variation strictly related to NaCl stress. The down-regulated HSPs meant the function to repair cells that have suffered damage weaken during stress process. Furthermore, except for HSP70 in M. zapota leaves, the HSPs in the two species were all small heat shock proteins (sHSPs) with molecular weights ranging from 15 to 42 kDa.