Effects of iron toxicity on the morphological and biological characteristics of rice root border cells
2017
Zhang, Yi | Wu, Yuhuan | Xu, Gendi | Song, Jinmin | Wu, Tonggui | Mei, Xiaoman | Liu, Peng
Toxicity of Fe ²⁺ is one of the major constraints for lowland rice production in tropical and subtropical areas. The root tip is a primary site of iron (Fe ²⁺) toxicity in rice. To explore the effects of iron toxicity on the morphological and biological characteristics on the border cells in rice (Oryza sativa L.), experiments were carried out using the border cells in two cultivars. The experimental results revealed the following properties of border cells shared by both rice cultivars: the first border cells appeared almost synchronously with the emergence of the primary root tip; the number of border cells reached maximum when the root was 25 mm long; the border cells were most viable when the root length was 20 mm; and the relative activity of pectin methylesterase (PME) was the highest when the root length was 2 mm. The two rice cultivars exhibited different trends in their response to Fe ²⁺ toxicity: the number of root border cells in Fe ²⁺-resistant Zhongyou 9288 increased when experiencing low levels of Fe ²⁺ treatment, but then declined at higher Fe ²⁺ levels. The number of root border cells in Fe ²⁺-sensitive Shanyou No. 10, however, declined rapidly when the concentration of Fe ²⁺ increased. The results also showed that Fe ²⁺ toxicity hindered the development of root border cells of both rice cultivars, but the Fe ²⁺ sensitive variety experienced thickened the root cap cell walls that led to programmed cell death.
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