Populus bolleana is a variety of P. alba, commonly used in poplar breeding programs in China. Developmental biology that involves staminate flowers, microsporogenesis and microgametogenesis of P. bolleana is essential for Populus improvement in cross breeding for better characteristics in sexual reproduction. Flower morphology and pollen development were described and illustrated using anatomical, sectioning and stain-clearing techniques. The results show that microsporocytes undergo a regular meiotic process, but some multi-nucleate microspores occur at the microspore stage. It takes five days for microsporocytes to develop to mature pollen by forcing flower branches under greenhouse conditions. Additionally, an important relationship was found between stages of meiosis and anther colors. Microspore tetrads formed when the anther color turned yellow, whereas, when the pollen matured, the anther was red and the tapetum degenerated completely. When mature pollen grains are formed, flower buds develop into male catkins. In the end, filament elongated and pollen grains were released from dehisced anthers.

Pollen development and floral morphology of Populus pseudo-simonii were investigated by stain-squashing and anatomical techniques. It took approximately 16 days for the pollen to develop from pollen mother cells to mature pollen in the greenhouse. Meiosis of pollen mother cells was regularly applied and completed by a process of simultaneous cytokinesis. Pollen development was considerably asynchronous. The meiotic division was initiated at the bulgy middle position of the flower bud and proceeded towards the tip and base of the bud. The number and size of the nucleoli varied during pollen development and at most eight nucleoli formed in each daughter nucleus at the meiotic telophase, suggesting a paleopolyploid origin of the genus Populus. An association between floral morphology and pollen development was found and the ratio of width to length of flower buds or catkins presented an S-shaped curve related to pollen development as a function of time. The investigation on the pollen development and floral morphology of P. pseudo-simonii is important for further cross breeding programs of the section Tacamahaca.

A highly stable and effective catechol biosensor was prepared by immobilizing polyphenol oxidase (PPO) into polyaniline (PANI) film by using the direct electropolymerization (one-step) process in conjunction with cross-linking with glutaraldehyde. The results of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed that the immobilization of PPO was successful. The biosensor has a fast response to catechol (10 s) with a linear range of 1.0-100 mM and a detection limit of 0.01 mM. The maximum response current (I max ) and the Michaelis-Menten constant (k' m ) were found to be 7.94 mA and 81.32 mM, respectively. The activation energy (E a ) of the PPO catalytic reaction was 16.5 kJ=mol. The biosensor exhibited good stability by retaining 80% of its original activity when stored in a dry state at 4 C for up to 5 months.

Phosphorus (P) is an important macronutrient for all lives, but it is also a finite resource. Therefore, it is important to understand how to increase the P availability and plant uptake. The endophytes can help host plants to improve P uptake and will be apparently affected by plant genotypes. To investigate the mechanism of root endophytes in promoting P uptake of peach rootstocks, we analyzed the variations of the root endophytic fungal and bacterial communities of peach rootstocks with different P efficiencies under high or low level of P addition. Results showed that Proteobacteria was the dominant bacterial phylum in the roots of all rootstocks under the two levels of P addition. At low P level, the abundance of Actinoplanes in phosphorus-inefficiency root system was apparently higher than that at high P level. Actinoplanes produced important secondary metabolites, improving the stress resistance of plants. Under high P condition, the abundance of Ferrovibrio was higher in Qing Zhou Mi Tao than in Du Shi. Fe oxides considerably reduced the availability of applied P, which partially explained why the P utilization in Qing Zhou Mi Tao is inefficient. Further, Ascomycota was the dominant fungal phylum in the roots of all rootstocks under different levels of P addition. The fungi community of roots varied in different rootstocks at each P level, but was similar for the same rootstock at different P levels, which indicated that genotype had a greater effect than P addition on the fungal community of peach rootstocks.

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