Different plant species respond differently to nCeO2 under different culturing conditions: for some, deficiency of P enhances the accumulation of Ce (mainly Ce3+) and phytotoxicity.

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The release of metal ions may play an important role in toxicity of metal‐based nanoparticles. In this report, a life cycle study is carried out in a greenhouse, to compare the effects of ceria nanoparticles (NPs) and Ce3+ ions at 0, 50, 100, and 200 mg Ce kg−1 on plant growth, biological and physiological parameters, and nutritional value of soil‐grown common bean plants. Ceria NPs have a tendency to negatively affect photosynthesis, but the effect is not statistically significant. Ce3+ ionic treatments at 50, 100, and 200 mg Ce kg−1 result in increases of 1.25‐, 0.66‐, and 1.20‐fold in stomatal conductance, respectively, relative to control plants. Both ceria NPs and Ce3+ ions disturb the homeostasis of antioxidant defense system in the plants, but only 200 mg Ce kg−1 ceria NPs significantly induce lipid peroxidation in the roots. Ceria NP treatments tend to reduced fresh weight and to increase mineral contents of the green pods, but have no effect on the organic nutrient contents. On the contrary, Ce3+ ion treatments modify the organic compositions and thus alter the nutritional quality and flavor of the green pods. These results suggest that the two Ce forms may have different mechanisms on common bean plants.

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The recognition of natural hybridization can help to understand the origin and maintenance of biodiversity. Based on intermediate morphology and overlapped distribution, Torreya grandis var. jiulongshanensis Z. Y. Li, Z. C. Tang & N. Kang was regarded as a putative natural hybrid between T. jackii Chun and T. grandis Fort. ex Lindl. in southeast China. This study tested the hybridization origin of T. grandis var. jiulongshanensis using nuclear internal transcribed spacer (ITS) and cytoplasm (chloroplast rbcL and rpl16 and mitochondrial rps3) DNA sequences. The results showed that most heterozygous sites of nuclear ITS sequences in T. grandis var. jiulongshanensis showed additivity between T. jackii and T. grandis. Cloned ITS sequences of T. grandis var. jiulongshanensis separately clustered with T. jackii and T. grandis in the phylogenetic analyses. Meanwhile, all of chloroplast and mitochondrial haplotypes of T. grandis var. jiulongshanensis were identical to those of T. jackii, not T. grandis. On the chloroplast DNA phylogenetic trees, T. grandis var. jiulongshanensis were grouped into the clade of T. jackii. These results suggest that T. grandis var. jiulongshanensis is a natural hybrid between T. jackii (maternal parent) and T. grandis (paternal parent). This study also implies that T. grandis should be cultivated with caution near the sites of T. jackii, because the endangered status of the latter might be deteriorated due to hybridization.