Degeneration of photosynthetic capacity in mixotrophic plants, Chimaphila japonica and Pyrola decorata (Ericaceae)

The evolution of photosynthesis is an important feature of mixotrophic plants.Previous inferences proposed that mixotrophic taxa tend to retain most genes relating to photosynthetic functions but vary in plastid gene content.However,no sequence data are available to test this hypothesis in Ericaceae.To investigate changes in plastid genomes that may result from a transition from autotrophy to mixotrophy,the plastomes of two mixotrophic plants,Pyrola decorata and Chimaphila japonica,were sequenced at Illumina's Genome Analyzer and compared to the published plastome of the autotrophic plant Rhododendron simsii,which also belongs to Ericaceae.The greatest discrepancy between mixotrophic and autotrophic plants was that ndh genes for both P.decorata and C.japonica plastomes have nearly all become pseudogenes.P.decorata and C.japonica also retained all genes directly involved in photosynthesis under strong selection.The calculated rate of nonsynonymous nucleotide substitutions and synonymous substitutions of protein-coding genes(dN/dS) showed that substitution rates in shade plants were apparently higher than those in sunlight plants.The two mixotrophic plastomes were generally very similar to that of non-parasitic plants,although ndh genes were largely pseudogenized.Photosynthesis genes under strong selection were retained in the two mixotrophs,however,with greatly increased substitution rates.Further research is needed to gain a clearer understanding of the evolution of autotrophy and mixotrophy in Ericaceae.

Lanthanide atoms doped arsenene monolayer:Enhanced magnetic anisotropies,huge magnetic moments and significant strain-modulated effects

Employing the spin-polarized density functional theory(DFT),we investigated the magnetic and optical properties of buckled arsenene(β-As) after doping a whole series of lanthanide(Ln) atoms.Our results demonstrate that Ln atoms can be stably doped into the single layer arsenene.Upon doping Ln atoms,La,Ce,Pr,Nd,Gd,Dy and Lu@arsenene behave dilute magnetic semiconductor(DMS) properties,while the Pm,Sm,Eu,Ho,Er and Tm@arsenene show half metallic characteristics.Most of Ln@arsenene systems favor the long-range ferromagnetic ordering.The maximum of Ln-doped systems' magnetic moments and magnetic anisotropy energy(MAE) can reach 8 μ_(B) and 7.48 meV,respectively.The doping of Ln atoms into arsenene improves the optical responses in visible and infrared regions.Strain can alter the magnetic coupling between Sm and the neighboring As atoms and reduce the system's magnetic moment.Besides,strain can improve the MAE of these systems,accompanied by the change of the easy magnetization of Sm@arsenene.Furthermore,compressive and tensile strains effectively improve the optical responses in visible and ultraviolet region,respectively.Based on the obtained results,we believe that the Ln@arsenene monolayer has application prospects in photoelectronics and spintronics such as high-density memory devices.