The lignin and cellulose Tanespimycin in vivo contents were higher in the mechanical tissue layer, where the cells around the vascular bundles are rich in lignin and cellulose . In our study, a strong relationship was observed between lodging resistance and WOMT (r = 1.000, P < 0.01), indicating that mechanical tissues
play an important role in lodging resistance of wheat. Compared with hollow stemmed wheat, the solid stemmed genotype was more resistant to lodging as a result of its comparatively wider stem wall and greater amount of mechanical support tissues. Zuber et al.  reported that 49.7% of the variation in lodging in wheat was explained by variation in stem weight. It is suggested that, along with plant height, stem weight and stem diameter might be helpful in developing new lodging-resistant wheat cultivars. In this study, the high correlation between WOL and lodging resistance (r = 0.986, P < 0.05) suggested that WOL was also an important factor affecting the rigidity of wheat stems. However, WOL was not included in the model of predicting lodging resistance. This probably results from the strong correlation between WOL and WOMT (r = 1.000, P < 0.01). Khanna  and Hamilton  found that the stem lodging of wheat, triticale (× Triticosecale Wittmack), rye (Secale
cereale L.) and oat (Avena sativa L.) decreased in proportion to the number of vascular bundles. ZD1839 purchase In contrast, Dunn and Briggs  found no relationship between the number of vascular bundles and lodging response in barley (Hordeum vulgare L.). Among the four DNA Methyltransferas inhibitor wheat genotypes investigated in this study, few differences were found with respect to the number of vascular bundles, and there were no significant correlations
between the presence of large or small vascular bundles and lodging response. These inconsistent results might be due to the inherent genetic differences between the genotypes used in different studies. A layer of thick-walled, lignified sclerenchyma near the periphery of the stem and around the vascular bundles significantly increases lodging resistance ,  and . In our study, the correlation between lodging resistance and AOVB was not significant. In a one-variable model with WOMT, the coefficient of determination (R2) was 0.999 (P < 0.01). The value increased to 1.000 (P < 0.01) in a two-variable model with the addition of AOVB (data not shown), suggesting that AOVB might also play an important role in lodging resistance. Wiesner staining involves the cinnamaldehyde residue of lignin, and the color intensity reflects the total lignin content. However, there was no difference in the color of the mechanical tissue layer among the four wheat genotypes examined, indicating similar lignin contents. Li  reported that maize (Zea mays L.) hybrids with higher amounts of lignin were more prone to stalk breakage. In contrast, Hondroyianni et al.