Phenotypic Characterization of a Female Sterile Mutant in Rice

A female sterile mutant, derived from a spontaneous mutation, was first discovered In rlce （Oryzs satlvs L. sep. Indlca） restorer llne 202R. Wlth normal fiowerlng, the mutant exhlblts an extremely low seed-sattlng rate. When the mutant Is crossed as a pollen donor, the seeds set normally; whereas when It Is used as a pollen recelver, no seeds are obtalned even wlth mlxed pollen gralns of dlfferent varletles sprlnkled over the atlgmas. The fioret of the mutant, conslatlng of slx stamens and one platll, looks the same as that of the wlld type In the malefemale organs, except that less than 10% of the mutant florets have three atlgmas on the ovary. Although the mutant has a low seed-setting rate, Its pollen fertility Is approximately 87.1%, which Is equal to that of the wild type. In addition, more than 90% of the mature embryo sacs of the mutant have complete Inner structures. At every stage after pollination, the sperm, embryo, and endosperm are not found In the mutant embryo sac, whereas the disintegration of the egg cell that does not accomplish fertilization Is visible. Through observetlons with a fluorescence microscope, we have found that the pollen grains germinate normally, whereas the pollen tube abnormally elongates in the style-transmitting tissue. The mutant pollen tubes display various defects In the style, such as slower elongation, conversed elongation, distorted elongation, swollen tips, or branched tips. As a result, the growth of the pollen tubes ceases In the style, and, therefore, the pollen tubes cannot reach the embryo sac and the process of double fertilization Is blocked. Based on these observations, we conclude that this mutant, designated as fs-202R, Is a novel type of female sterile mutation In rice, which causes the arrest of the elongation of the pollen tube.

Self-assembled uniform double-shelled Co_(3)V_(2)O_8 hollow nanospheres as anodes for high-performance Li-ion batteries

Hollow micro-/nanostructures have achieved great success in the field of renewable battery materials by reducing the volume change and promoting the ion transport.Double-shelled Co_(3)V_(2)O__(8)hollow nanospheres(CVODSS)were synthesized using a facile solvothermal method followed by a thermal treatment in the absence of any surfactant.Meanwhile,two other architectures of hollow nanospheres and nanoparticles were obtained by changing the annealing temperature.Benefiting from the desired hollow structure,the CVO-DSS electrode exhibits excellent lithium storage properties as an anode.It exhibits a reversible discharge capacity of 1210 m Ah·g^(-1)at200 m A·g^(-1)after 100 cycles and a satisfactorily high rate capacity of 628 m Ah·g^(-1)after 800 cycles at 5000 m A·g^(-1).These hollow nanostructures can efficiently enhance the contact area of the electrolyte/electrode interface,promote the diffusion of lithium ions and electrons and slow down the capacity loss during long cycles.