Background: Maize is one of the important cereal food crops in the world. High temperature stress causes adverse influence on plant growth. When plants are exposed to high temperatures, they produce heat shock proteins (HSPs), which may impart a generalized role in tolerance to heat stress. Proteome analysis was performed in plant to assess the changes in protein types and their expression levels under abiotic stress. The purpose of the study is to explore which proteins are involved in the response of the maize plant to heat shock treatment. Results:We investigated the responses of abundant proteins of maize leaves, in an Egyptian inbred line of maize "K1", upon heat stress through two-dimensional electrophoresis (2-DE) on samples of maize leaf proteome. 2-DE technique was used to recognize heat-responsive protein spots using Coomassie Brilliant Blue (CBB) and silver staining. In 2-D analysis of proteins from plants treated at 45°C for 2 h, the results manifested 59 protein spots (4.3%) which were reproducibly detected as new spots where did not present in the control. In 2D for treated plants for 4 h, 104 protein spots (7.7%) were expressed only under heat stress. Quantification of spot intensities derived from heat treatment showed that twenty protein spots revealed clear differences between the control and the two heat treatments. Nine spots appeared with more intensity after heat treatments than the control, while four spots appeared only after heat treatments. Five spots were clearly induced after heat treatment either at 2 h or 4 h and were chosen for more analysis by LC-MSMS. They were identified as ATPase beta subunit, HSP26, HSP16.9, and unknown HSP/Chaperonin. Conclusion:The results revealed that the expressive level of the four heat shock proteins that were detected in this study plays important roles to avoid heat stress in maize plants.

The heat shock protein (HSP) family is one of the proteins universally accumulated under heat stress condition. Four Egyptian maize inbred lines (Zea mays L.) were studied to identify heat shock proteins under heat stress at 45°C as protein markers for detecting the thermo-tolerance inbreds. The protein fingerprints of four inbred lines were performed by grain total-soluble protein electcophoretic analysis. The protein electrophoretic analysis showed 18 bands in a distinct pattern of K1 and K7 inbred lines, while 17 bands were present in G342 and Rg59 inbred lines as another distinct pattern indicating different genotypes. The high temperature effect on four maize inbred lines exposed to 45°C for 2 and 4 hours at 14-days old seedlings besides control (25°C) was studied. Several protein bands varied between low and intermediate molecular weights were induced after exposing to heat stress at 45°C. Four bands of heat shock proteins with molecular weights of 82, 22, 17 and 10 kDa appeared in the inbred line K1 after exposing to 45°C for 2 and 4 hours which may be indication of thermo-tolerance. Four and seven bands were enhanced after exposing to high temperature for 4 hours at 45°C which appeared more concentrated in the patterns of K7 and G342 inbred lines, respectively.

Two field experiments were carried out to evaluate six mutant lines having a good agronomic potential comparing with their original varieties Sids5, Sids6 and Sids7. The results showed significant decrease in plant height for all semidwarf mutant lines. The reduction of plant height reached to 19.83% comparing with the original varieties. Some semidwarf mutant lines (line 5-1, line 6-1 and line 7-1) exhibited highly significant values for spike length, number of spikes/plant and grain yield/plant as compared to their original varieties. The original varieties manifested highly significant values for number of grains/spike as compared to their all semidwarf mutant lines. The results indicated that wheat semidwarf mutants of line 5-1, line 6-1 and line 7-1 are promising mutant lines, since they gave high grain yield. All studied genotypes were electrophoreticaly analyzed for grain water-soluble proteins. The discrimination of such mutant lines and their parental varieties revealed differences in their banding patterns and occurrence of genetic variation between such genotypes. The electrophoretic analyses of proteins revealed some newly induced bands such as bands with molecular weights of 114.04, 87.82, 41.55 and 11.90 kDa. Such newly bands, which were not existed in the unirradiated varieties, may be originated from gamma radiation effects. It is expected that gamma rays modified the structure of some genes in the mutant lines, and these modifications appeared as absence of protein bands with molecular weights of 72.60 kDa in sids5 and 24.39 kDa in Sids6. The variety Sids7 exhibited the highest numbers of new protein bands after irradiation. The results revealed positive relations between number of bands in the protein patterns of Sids5 and Sids6 and their mutant lines, and for most of agronomic and yield traits.

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