Nutrient Component, Cell Ultrastructures, and Cd Accumulation and Subcellular Localization in the Cottonseeds of Three Upland Cotton Cultivars Under Cd Stress

¡¡¡¡Cadmium (Cd) contamination has been one of the most serious heavy metal pollutions in agricultural soils and constitutes a serious challenge to food production worldwide. A pot experiment was performed in order to study the Cd-induced alterations in seed quality at maturity in two transgenic cotton cultivars, ZD-90 and SGK3, and an upland cotton standard line, TM-1. The results shown that the Cd contents in the kernels were increased linearly over their respective controls with the elevation of Cd stress levels, i.e. 200¦ÌM, 400¦ÌM, and 600 ¦ÌM. SGK3 accumulated more Cd than others, indicating Cd accumulation capability variated greatly among the upland cotton genotypes. Protein content in the kernels was increased under Cs stress generally, but those at 600?M Cd level was lower than that that under 400?M Cd level. The changes in oil content were inversed to that of protein content. The significant ultra-structural changes in the cells of cottonseed were induced by Cd stress, especially in high Cd levels, which were more obvious in TM-1, followed by ZD-90 and SGK3. Changes in plasmolytic shrinkage, disintegration of nucleus, cell wall thickening, and eventual cell collapse and disintegration were observed in the cells of cottonseeds under Cd stress. Transmission electron microscope (TEM) observation and energy dispersive X-ray analysis (EDAX) confirmed that Cd existed in the form of rings and crystals as well as electron dense granules, occurred in the intercellular space, the cytoplasm, and the cell wall. From the present experiment, SGK3 was found to be a tolerance cultivar to Cd stress with greater Cd accumulation and sequestration in cottonseeds. It is a suitable cotton cultivar to plant in Cd polluted soil and clean up Cd contaminated soils by phytoremediation technology.