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An artificial muscle is a type of actuator that can contract, extend, or rotate when exposed to external stimuli (e.g., electrochemical, temperature, pressure, humidity, light, etc.). Twisted fibers can be used in powerful artificial muscles and can convert volume expansion upon stimuli into torsional rotation or axial contraction due to their spiral structure. Upon twist insertion, torsional stress is produced in the fiber, and fiber volume expansion increases the torsional stress, resulting in fiber untwisting. By inserting twist to form a self‐coiled fiber, fiber volume expansion causes the contraction of this self‐coiled fiber if the fiber is torsionally tethered. Fiber‐based artificial muscles have potential applications in a variety of fields such as temperature‐regulating clothing, soft robots, prosthetics, and exoskeletons. Herein, the recent progress in twisted‐fiber artificial muscles with different actuation stimuli, such as thermal, photo, solvent adsorption or infiltration, and electrochemical, is reviewed. The opportunities and challenges for twisted‐fiber artificial muscles are also discussed. Therefore, this review provides an insight for designing high‐performance and multi‐functional twisted‐fiber artificial muscles and motivates the development and applications of fiber‐based artificial muscle in future research. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the heterosis of partial interspecific hybrids between African rice (Oryza glaberrima Steud.) and Asian rice (Oryza sativa L.) and its correlation with genetic distance. Sixty‐nine rice accessions including 57 introgression lines (ILs) were tested for population structure and genetic distance. Forty‐nine crosses between ILs and a test variety, Shengtai1 (ST1), were evaluated for midparent heterosis of nine agronomic traits. Population structure, genetic distance, and the proportion of O. glaberrima genome (PGG) of ILs and heterosis of the test crosses were estimated and analyzed. The PGG of the ILs ranged from 1.22 to 49.71%, with an average of 15.29%. The genetic distance between parents of the tested crosses was positively correlated to the PGG of ILs (r =.95, P <.01). Positive heterosis was scored on plant height (12.23%), panicles per plant (19.97%), panicle length (10.37%), spikelets per panicle (24.06%), thousand‐grain weight (14.00%), length/width ratio of grain (0.03%), and grain yield per plant (60.77%) of the partial interspecific hybrids. Although the introgression of more African genomic genes could effectively increase the genetic distance between ILs and the test variety that lead to positive heterosis for most agronomic traits, it could also increase the possibility of the occurrence of interspecific sterility that might decrease the seed setting rate and result in negative heterosis (−2.57%). These data indicated that the introgression of African rice genes into the genome of Asian rice could effectively broaden the genetic diversity, and the deployment of ILs as parents could be a potential way for exploiting interspecific heterosis in rice. [ABSTRACT FROM AUTHOR]

The introduction of closely related species genomic fragments is an effective way to enrich genetic diversity and creates new germplasms in crops. Here, we studied the genetic diversity of an introgression line (IL) population composed of 106 ILs derived from an interspecific tetra cross between O. glaberrima and O. sativa (RAM3/Jin23B//Jin23B///YuetaiB). The proportion of O. glaberrima genome (PGG) in the ILs ranged from 0.3% to 36.7%, with an average value of 12.32% which is close to the theoretically expected proportion. A total of 250 polymorphic alleles were amplified by 21 AFLP primer combinations with an average of 12 alleles per primer. Population structure analysis revealed that the IL population can be divided into four genetically distinct subpopulations. Both principal component analysis and neighbor-joining tree analysis showed that ILs with a higher PGG displayed greater genetic diversity. Canonical discriminant analysis identified six phenotypic traits (plant height, yield per plant, filled grain percentage, panicle length, panicle number and days to flowering) as the main discriminatory traits among the ILs and between the subpopulations and showed significant phenotypic distances between subpopulations. The effects of PGG on phenotypic traits in the ILs were estimated using a linear admixed model, which showed a significant positive effect on grain yield per plant (0.286±0.117), plant height (0.418 ± 0.132), panicle length (0.663 ± 0.107), and spikelet number per panicle (0.339 ± 0.128), and a significant negative effect on filled grain percentage (-0.267 ± 0.123) and days to flowering (-0.324 ± 0.075). We found that an intermediate range (10% − 20%) of PGG was more effective for producing ILs with favorable integrated agronomic traits. Our results confirm that construction of IL population carrying O. glaberrima genomic fragments could be an effective approach to increase the genetic diversity of O. sativa genome and an appropriate level of PGG could facilitate pyramiding more favorable genes for developing more adaptive and productive rice. [ABSTRACT FROM AUTHOR]