Overall study of solar simulation optical system with large irradiated surface using free-form concentrator to improve uniformity.

Large irradiation surface solar simulator often has the problem of low irradiation uniformity. Therefore, a method for designing a large irradiation surface solar simulator with high irradiation uniformity is proposed. According to the law of conservation of energy and the edge-ray principle of non-imaging optics, the free-form surface concentrator is designed and optimized by using the simulated annealing algorithm based on Bessel curve to improve the incident beam uniformity of the integrator. The optical integrator and projection system are also designed and optimized to eliminate aberrations, improve light efficiency, and enlarge the irradiation area. The design is verified using LightTools software and achieves an effective irradiation size of Φ1200 mm with an irradiance of a solar constant and an irradiation uniformity of less than 2.0%. This study provides accurate and reliable solar irradiation for laboratory calibration and performance testing of spacecraft payloads.

A base substitution in OsphyC disturbs its Interaction with OsphyB and affects flowering time and chlorophyll synthesis in rice.

BACKGROUND: Phytochromes are important photoreceptors in plants, and play essential roles in photomorphogenesis. The functions of PhyA and PhyB in plants have been fully analyzed, while those of PhyC in plant are not well understood. RESULTS: A rice mutant, late heading date 3 (lhd3), was characterized, and the gene LHD3 was identified with a map-based cloning strategy. LHD3 encodes phytochrome C in rice. Animo acid substitution in OsphyC disrupted its interaction with OsphyB or itself, restraining functional forms of homodimer or heterodimer formation. Compared with wild-type plants, the lhd3 mutant exhibited delayed flowering under both LD (long-day) and SD (short-day) conditions, and delayed flowering time was positively associated with the day length via the Ehd1 pathway. In addition, lhd3 showed a pale-green-leaf phenotype and a slower chlorophyll synthesis rate during the greening process. The transcription patterns of many key genes involved in photoperiod-mediated flowering and chlorophyll synthesis were altered in lhd3. CONCLUSION: The dimerization of OsPhyC is important for its functions in the regulation of chlorophyll synthesis and heading. Our findings will facilitate efforts to further elucidate the function and mechanism of OsphyC and during light signal transduction in rice.

Potentially Useful Dwarfing or Semi-dwarfing Genes in Rice Breeding in Addition to the sd1 Gene.

The "Green revolution" gene sd1 has been used widely in the breeding of modern rice varieties for over half a century. The application of this gene has increased rice yields and thereby supported a significant proportion of the global population. The use of a single gene, however, has raised concerns in the scientific community regarding its durability, especially given the bottleneck in genetic background and the need for large input of fertilizer. New dwarfing or semi-dwarfing genes are needed to alleviate our dependence on the sole "Green revolution" gene. In the past few years, several new dwarfing and semi-dwarfing genes as well as their mutants have been reported. Here, we provide an extensive review of the recent discoveries concerning newly identified genes that are potentially useful in rice breeding, including methods employed to create and effectively screen new rice mutants, the phenotypic characteristics of the new dwarfing and semi-dwarfing mutants, potential values of the new dwarfing and semi-dwarfing genes in rice breeding, and potential molecular mechanisms associated with the newly identified genes.

Optical design of a solar simulator for meteorological fields to improve irradiance uniformity and expand the range of irradiation regulation.

Aiming at the problems of low irradiation uniformity and a narrow irradiance regulation range in the existing solar simulators, an optical design method for meteorological solar simulators with high irradiation uniformity and wide-range irradiance is proposed. Using a xenon lamp and a variable coefficient non-coaxial ellipsoid reflector as the concentrator system, we analyze the causes of stray light in the optical integrator. The optimal design method of the integrator based on the anti-crosstalk diaphragm and the light propagation matrix model, which effectively suppress the stray light, is proposed. The irradiance regulation system is designed to continuously regulate the irradiance in a wide range. The optimal design method of the collimated system is given. The rationality of the system design is verified by the simulation of LightTools software. The results show that within the effective irradiation surface of 100mm×100mm, the irradiance is continuously adjustable in the range of 100-1400W/m2, and the irradiation uniformity is better than 99.10% under different irradiances. This research breaks through the limitations of low irradiation uniformity and a narrow irradiance adjustment range of traditional meteorological solar simulators and can provide accurate and reliable solar irradiance for the verification and calibration of pyranometers.

Mutation of rice BC12/GDD1, which encodes a kinesin-like protein that binds to a GA biosynthesis gene promoter, leads to dwarfism with impaired cell elongation.

The kinesins are a family of microtubule-based motor proteins that move directionally along microtubules and are involved in many crucial cellular processes, including cell elongation in plants. Less is known about kinesins directly regulating gene transcription to affect cellular physiological processes. Here, we describe a rice (Oryza sativa) mutant, gibberellin-deficient dwarf1 (gdd1), that has a phenotype of greatly reduced length of root, stems, spikes, and seeds. This reduced length is due to decreased cell elongation and can be rescued by exogenous gibberellic acid (GA3) treatment. GDD1 was cloned by a map-based approach, was expressed constitutively, and was found to encode the kinesin-like protein BRITTLE CULM12 (BC12). Microtubule cosedimentation assays revealed that BC12/GDD1 bound to microtubules in an ATP-dependent manner. Whole-genome microarray analysis revealed the expression of ent-kaurene oxidase (KO2), which encodes an enzyme involved in GA biosynthesis, was downregulated in gdd1. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that GDD1 bound to the element ACCAACTTGAA in the KO2 promoter. In addition, GDD1 was shown to have transactivation activity. The level of endogenous GAs was reduced in gdd1, and the reorganization of cortical microtubules was altered. Therefore, BC12/GDD1, a kinesin-like protein with transcription regulation activity, mediates cell elongation by regulating the GA biosynthesis pathway in rice.