The Cytology Features Of The High-yield Wheat Varieties

The new wheat (Triticum asetivum L.) variety Xiaoyan 81, a comparatively lodging resistant cultivar, is a selected offspring from its maternal parent Xiaoyan 54 which is a commercial cultivar with good quality and broad adaptability and paternal parent 8602 which has a higher ratio of the grain-weight and high yield. The relationship of culm cytological features and lodging resistance was studied by means of various techniques, including culm strength determination, anatomical analysis, histochemical staining, confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), Fourier transfer infrared spectrometry (FT-IR) and Klason lignin determination. In addition, structural and functional changes in chloroplast of the flag leaf and the awn in cv. Jing 411 were investigated using transmission electron microscope (TEM) and oxygen electrode during series developmental stages.First of all, the prostrate tester was used for testing the culm strength of cv. xiaoyan 81 in comparison with its maternal parent cv. xiaoyan 54 and paternal parent cv. 8602 during the period from the milk stage to dough ripe stage. The result showed that the culm strength of cv. Xiaoyan 81 is stronger than cv. Xiaoyan 54 and cv. 8602.Subsequently, the culms of cv. Xiaoyan81 together with its maternal parent cv. Xiaoyan 54 and paternal parent cv. 8602 were compared at the morphological level to determine the anatomical features that were associated with these traits. This analysis revealed that the lodging resistant cv. Xiaoyan8l culms were shorter, possessed smaller diameter and thicker width, higher thickness-diameter ratio and higher percentage of mechanical tissue, less number of vascular bundles and more in unit area, compared with its parents.Furthermore, the lignin content determination according to Klason's method revealed a much higher lignin content in the culm of cv. Xiaoyan8l than that in the cv. Xiaoyan 54 and cv. 8602. Semi-quantitative analysis of lignin with confocal laser scanning microscopy (CLSM) and histochemical staining indicated that lignin deposited in the cell wall of mechanical tissues and vascular bundles in cv. Xiaoyan 81. Fourier transfer infrared spectroscopy (FTIR) showed that the lignin characteristic units in cv. Xiaoyan 81 were higher than that of its parents, and cv. Xiaoyan 81 possessed much syringl units, which likely contributed much to lodging resistance.-3-Moreover, in contrast to its parents, cv. Xiaoyan 81 possessed shorter fiber and length-width ratio, thicker fiber wall, small pith and large fiber wall-pith ratio. Therefore, the fiber in cv. Xiaoyan 81 was hard and the original fiber net construction was not easy to break. FT-IR analysis showed that C-H flex oscillation of cellulose in cv. Xiaoyan 81 was stronger when comparing with its parents. And the cellulose microfibrils array in the cell secondary wall was captured using atomic force microscope.In addition, structural and functional changes in the awn and the flag leaf were studied. Awns are organs directly exposed to light but they contain more grana per chloroplast, bigger granal stacks and more thylakoids per grana] stacks. And non-leaf organs have fewer and smaller chloroplasts than leaves. In the meanwhile, studies on the rates of photosynthetic oxygen evolution of awns and flag leaves in wheat were carried out. It demonstrated that the photosynthetic contribution of non-leaf organs was 6%-28% of that of flag leaves. The decline in photosynthetic activity was closely related to the reduction of chloroplast numbers. Interestingly, it was observed that the photosynthetic capacity in the aging plant declined earlier in leaf organs than in non-leaf organs, which suggested that non-leaf organs were still functional in the later development stages, when leaves had been yellowish and exhausted.In the summary, all of these findings provided anatomical and chemical evidence for a better quality in biomechanics of culm in cv. XiaoyanSl than that in its parents. The awns contribute much to the photosynthesis as well as the leaf.