Identification of candidate genes and clarification of the maintenance of the green pericarp of weedy rice grains

The weedy rice (Oryza sativa f. spontanea) pericarp has diverse colors (e.g., purple, red, light-red, and white). However, research on pericarp colors has focused on red and purple, but not green. Unlike many other common weedy rice resources, LM8 has a green pericarp at maturity. In this study, the coloration of the LM8 pericarp was evaluated at the cellular and genetic levels. First, an examination of their ultrastructure indicated that LM8 chloroplasts were normal regarding plastid development and they contained many plastoglobules from the early immature stage to maturity. Analyses of transcriptome profiles and differentially expressed genes revealed that most chlorophyll (Chl) degradation-related genes in LM8 were expressed at lower levels than Chl a/b cycle-related genes in mature pericarps, suggesting that the green LM8 pericarp was associated with inhibited Chl degradation in intact chloroplasts. Second, the F2 generation derived from a cross between LM8 (green pericarp) and SLG (white pericarp) had a pericarp color segregation ratio of 9:3:4 (green:brown:white). The bulked segregant analysis of the F2 populations resulted in the identification of 12 known genes in the chromosome 3 and 4 hotspot regions as candidate genes related to Chl metabolism in the rice pericarp. The RNA-seq and sqRT-PCR assays indicated that the expression of the Chl a/b cycle-related structural gene DVR (encoding divinyl reductase) was sharply up-regulated. Moreover, genes encoding magnesium-chelatase subunit D and the light-harvesting Chl a/b-binding protein were transcriptionally active in the fully ripened dry pericarp. Regarding the ethylene signal transduction pathway, the CTR (encoding an ethylene-responsive protein kinase) and ERF (encoding an ethylene-responsive factor) genes expression profiles were determined. The findings of this study highlight the regulatory roles of Chl biosynthesis- and degradation-related genes influencing Chl accumulation during the maturation of the LM8 pericarp

On the ‘ENGO + focal firm’ governance strategies of pollution of small and medium suppliers

Presently, the environmental pollution problem, especially that of the small and medium-sized enterprises, has become a bottleneck restricting the high-quality development of China’s economy. It is imperative to accelerate the construction of a collaborative governance system with multiple subject participation. The behavior modes of Environmental Non-governmental Organizations (ENGOs), a key player in environmental care, in collaborating with core enterprises to control pollution from small and medium-sized suppliers should be explored. Therefore, we constructed a collaborative governance system consisting of ENGOs, focal firms and small and medium-sized suppliers. Then a two-stage game model was established to analyze the strategies of the governance system. Specifically, we studied the collaborative green cooperation strategy and antagonistic pressure supervision strategy between ENGOs and focal firms, analyzed factors influencing the strategic choices of each subject, and gave the advantages of the cooperation strategies through further comparisons. The results showed that: Under the cooperation strategy, ENGOs provided knowledge of environmental protection to the focal firms, then both the audit efforts of focal firms and the environmental protection efforts of small and medium-sized suppliers were effectively improved. Since ENGOs could not fully obtain the pollution information of small and medium-sized suppliers or accurately trace it from their downstream focal firms, it was difficult to drive the supply chain’s endogenous governance by this external monitoring of ENGOs, making the effect of pressure supervision strategy limited. The effectiveness of green cooperation strategy was positively correlated with the knowledge absorption capacity of focal firms, the unit product revenue, and the focal firms' violation penalties for small and medium-sized suppliers. When ENGOs' violation penalties for small and medium-sized suppliers were higher, or the reputation loss of focal firms was higher, more unfavorable conditions of green cooperation strategy could be achieved. Accordingly, ENGOs should choose to cooperate with focal firms with strong knowledge absorption ability and high profit per product; focal firms should learn environmental protection knowledge to improve the screening standards and review capabilities, and promote the achievement of green cooperation strategy conditions by strengthening active information disclosure; the government should promote the collaboration between ENGOs and focal firms by issuing environmental guidelines

Monolithic Metamaterial-Integrated Graphene Terahertz Photodetector with Wavelength and Polarization Selectivity

The frequency spectra and polarization states of terahertz waves can convey significant information about physical interactions and material properties. Compact and miniaturized on-chip platforms for effective capturing of these quantities are being extensively investigated because of their promising potential for paramount applications of terahertz technology such as in situ sensing and characterization. Here, we present a metamaterial–graphene hybrid device that integrates the functions of photodetection, wavelength, and polarization selectivity into a monolithic architecture. Leveraging the ultrahigh design freedom of metamaterial optical properties and the electronically controllable hot-carrier-assisted photothermoelectric effect in graphene, our detector shows resonantly enhanced photoresponse at two specific target wavelengths with orthogonal polarizations. We demonstrate its versatile capabilities for spectrally selective and polarization resolved imaging on a single-chip platform that is free from advanced optical components. Our strategy is beneficial to the future development of multifunctional, compact, and low-cost terahertz sensors

Genome-wide selection and introgression of Chinese rice varieties during breeding

China is the largest rice-producing country, but the genomic landscape of rice diversity has not yet been clarified. In this study, we re-sequence 1070 rice varieties collected from China (400) and other regions in Asia (670). Among the six major rice groups (aus, indica-I, indica-II, aromatic, temperate japonica, and tropical japonica), almost all Chinese varieties belong to the indica-II or temperate japonica group. Most Chinese indica varieties belong to indica-II, which consists of two subgroups developed during different phases of rice breeding. The genomic segments underlying the differences between these subgroups span 36.32 Mb. The Chinese japonica rice varieties fall into the temperate japonica group, consisting of two subgroups based on their geographical distribution. The genomic segments underlying the differences between these subgroups span 27.69 Mb. These differentiated segments in the Chinese indica varieties span 45 genes with nonsynonymous mutations that are closely related to variations in plant height and grain width. Fifty-four genes with nonsynonymous mutations are associated with the differences in heading date between the two Chinese japonica subgroups. These findings provide new insights into rice diversity in China that will facilitate the molecular breeding