Expression Analysis Of Hormone-related Genes In Wheat

Wheat is one of the most important cereal crops, and its yield, quality and resistance has always been paid the attention from scientists. Hormones play critical roles on plant growth, development, reproduction and the regulation of plant resistance against biotic and abiotic stress. Hormones interact as a network to regulate plants. In this study, we analyzed the expression of the wheat plant hormone-related genes, and analyzed the cross-talk of hormone signaling in wheat. The main results are as follows:We collected 56 wheat and barley PR1 genes by BLAST searching with automatic parameters, and classified them into 7 groups by cluster analysis.91 pairs of group-specific and gene-specific PCR primers were designed and elevated on the cDNAs obtained from wheat heads and leaves treated by SA, MeJA (a close relative of JA), Fusarium graminearum and Blumeria graminis. Both reverse transcription PCR (RT-PCR) and Real-time Quantitative PCR (Q-PCR) methods were used. A total of 27 pairs of primers were qualified for RT-PCR. Among them, nine pairs can be used for Q-PCR in leaves and 10 for Q-PCR in heads. Gene expression of primer pairs measured by Q-PCR was similar to that elevated by RT-PCR. Results showed that PR1 genes from different groups were expressed in leaf and head tissues. And PR1 genes were responded to SA and MeJA in different ways. When using leaf samples,11 primer pairs gave brighter bands under the treatment of 1 mM MeJA than SA and water treatments. Among these 11 pairs,7 primer pairs gave brighter bands under the treatment of 10 mM SA than other SA treatments. The Q-PCR results showed that PR1 from group 1 was remarkably induced by 1 mM MeJA in leaves, and that PR1 from group 2 could be reduced by SA and MeJA in leaves. When using head samples, apart from PR1 from group 2 could be slightly induced by 1 mM SA and MeJA, no significant difference can be detected. Gene expression of primer pairs measured by Q-PCR was similar to that elevated by RT-PCR in head. Results showed that PR1 genes from different groups were expressed in leaf and head tissues. And PR1 genes were responded to SA and MeJA in different ways.For powdery mildew samples,20 of the 27 RT-PCR pairs amplified expected fragment. And 11 pairs of 20 showed brighter band than control. Five of the 9 qualified Q-PCR pairs for leaves were strongly enhanced in powdery mildew samples (7.4-33.8 folds of water treatment), mainly from group 1 and group 5, and the other 4 showed no significant difference. For FHB samples,19 of 27 RT-PCR pairs amplified expected fragment, and 12 pairs of them showed brighter band than control; 9 of the 10 qualified Q-PCR primer pairs for spike were strongly up-regulated in FHB samples (24.2-143.4 folds of water treatment), including the PR1 gene from group 1,2 and 5, and the last one showed no significant difference.Exogenous plant hormones were applied to wheat heads. Then RNAs were extracted from the treated heads and were used in microarray analysis. A total of 74 hormone-related genes were screened out preliminary. Among them, there were 12 auxin-related genes,9 gibberellin-related genes,15 abscisic acid-related genes,15 ethylene-related genes,8 cytokinins-related genes,3 salicylic acid-related genes,9 methyl jasmonate acid-related genes and 3 all hormone-related genes. Similarity search analysis shown that the functions of these genes were associated with wheat disease resistance, stress resistance, photosynthetic efficiency, energy conversion, transport and storage as well as hormone biosynthesis and metabolism. These genes will be helpful for further studies on hormone cross-talks in different wheat tissues.