Proteome Analysis Of Differentially Displayed Proteins In Rice Young Shoots Under Iron-deficiency Stress

Fe deficiency is a global and important nutritional problem particularly in crop plants grown on calcareous soils. Frequently,crop plants do not take up adequate amounts of iron from the soil,leading to chlorosis,poor yield and decreased nutritional quality. Extremely limited soil bioavailability of iron has led plants to evolve two distinct uptake strategies I and II.In this experiment we tried to investigate the responsive mechanism of rice(Oryza sativa) to Fe-defiency stress.Initially we observed the changes of rice physiological,morphological and cellular ultra-structure to Fe-defiency.Our results show that chloroplast and mitochondria of rice root cell were destroyed severely under Fe-defiency stress within 14 days.To further understand the response mechanism of rice in early days underiron-deficiency stress,high-resolution two-dimensional gel electrophoresis(2-DE) wasemployed to identify differentially displayed proteins expressed in rice leaves.Rice seedlings were grown l,3,5d in the absence of Fe and Fe-sufficiency respectively. Our aim was to characterize novel iron-stress related proteins and to determine their possible physiological function,by identifying gene products that are differentially present under the two circumstances.We detected nearly 600 spots on the gels with a pH 3-10 gradient and over 1000 spots on the gels with a pH 4-7 gradient when the proteins were visualized with colloidal Coomassie blue and analyzed by Z3 image software. Over 29 ,27 and 27 proteins were up-regulated,about 28,32 and 29 spots were down-regulated ,and 42,28,28 proteins were differentially espressed,compared with the control within ld,3d,and 5d of Fe-deficiency growth respectively.The sequence and functional information of these proteins were still in investigation.In addition,peptide mass fingerprints for 11 proteins that differentially displayed in rice root within 6d of Fe-deficiency growth were obtained with matrix assisted laser desorption/ionization-time of flight(MALDI-TOF) mass spectrometry.In conjunction with database searching,the 11 proteins were confirmed uniquely.Our work shows that 2-DE in combination with mass spectrometry can separated a proteome and identified its constituents effectively. This technique will be a useful strategy to investigate how plants react to Fe-deficiency at molecular level.