The results of this study showed no significant correlation between lodging and lignin or cellulose contents. However, the solid stemmed genotype had the highest lignin content and correlations between the degree of lodging

resistance and lignin (R2 = 0.978, P < 0.01) and cellulose (R2 = 0.944, P < 0.05) contents were both significant. Considering the results obtained from histochemical staining, we propose that lignin and cellulose play an important role in lodging resistance. All four genotypes analyzed in this study contained high levels of both lignin and cellulose. Further research is needed to increase our understanding of the role of chemical composition in lodging resistance in a wider range of wheat cultivars. Pith parenchyma EPZ015666 mouse plays an important role in stabilizing the stem against ovalisation and reducing the risk of local buckling and collapse [32], [33] and [34]. Stem stability is known to increase with the thickness of the parenchyma layer [3]. The effects of wind, rain, and other environmental forces can be absorbed by the parenchyma without heating or mechanical damage [4]. The available evidence suggests that pith parenchyma also plays an important role in lodging resistance. In this study, the percentage of pith varied significantly among the four genotypes. Since the solid stemmed wheat genotype had the greatest amount of pith, it was likely to be more resistant to lodging than the hollow ones.

Solid pith parenchyma also inhibits the growth Wnt inhibitor and development of sawfly (Cephus cinctus Norton) larvae in wheat stems, which is important for the control of wheat stem sawfly infestations. Sawfly larvae Methane monooxygenase feed on vascular tissue and parenchyma cells from the hollow regions inside the stem. When the larvae reach maturity, they migrate toward the base of stem, which at the time they eat a ring or girdle around the stem wall weakens the stem base and increases susceptibility of the plant to lodging [35]. The results of this study suggest

that a solid-stem wheat cultivar is less susceptible to lodging. The thick layer of mechanical tissue in the outer ring, as well as the solid pith parenchyma in the inner ring, of the solid stem increases resistance to lodging. In a U.S.A. study four microsatellite markers on chromosome 3BL (GWM247, GWM340, GWM547 and BARC77) were linked to a single solid stem QTL, which accounted for 76% of the variation in stem solidness in wheat [12]. In our study, only GWM247 and GWM340 were polymorphic and GWM247 was more closely linked to the single solid stem QTL and accounted for 77% of the variation in stem solidness. Our results were thus in agreement with the mapping results for solid stem in wheat cultivar Rampart [12], indicating that the same gene for solid stem may be present in XNSX and Rampart. In addition, our results showed that the solidness gene is closer to Xgwm247 (12.1 cM) than to Xgwm340 (16.