Chromosomal Transmission in F_2BC_1Hybrid Progenies between Sugarcane and Erianthus fulvus

[ Objective ] This study aimed to provide a scientific basis for breeding new sugarcane varieties with hybrid progenies of Erianthus fulvus and modifying existing sugarcane cultivars. [ Method] Chromosomal slides of the F2 and F2 BC1 hybrid progenies between sugarcane and E. fu/vus （2n = 20） and those of parental materials were prepared with the wall degradation hypotonic method, to further analyze the chromosomal transmission in the F2 and F2BC1 hybrid progenies and to investigate the chromosome transmission mechanism. [ Result ] The results showed that, somatic chromosome number varied in various hybrid progenies; chromo- somes from parents were transmitted into the somatic cells of F2 hybrids in ＂2n ＋ n＂ pattern and transmitted into the somatic cells of F2BC1 hybrids in ＂n ＋ n＂ pattern. [ Conclusion ] This study provided a preliminary cytological basis for further use of these materials in sugarcane breeding.

Karyotype Analysis of BC_1 and BC_2 Progenies between Sugarcane and Erianthus fulvus

In this study, karyotype analysis of F2BCl progenies between sugarcane （Saccharum spp. ） and Erianthusfulvus was conducted. The result showed that most chromosomes of YAU04/14, YAU09/02, YAU09/05, YAU09/26 and YAU09/52 are median region （m） chromosomes, while only a small amount of chromosomes are submedian （sin） chromosomes and median point （M） chromosomes. The karyotype formulae of five experimental materials are 2n = 106 = 98m ＋ 8sm, 2n = 106 - 2M ＋ 104m, 2n = 106 = 4M ＋ 96m ＋ 6sin, 2n = 102 = 2M ＋ 92m ＋ 8sin and 2n = 106 = 4M ＋ 96m ＋ 6sin, respectively. The karyotypes of all materials belong to symmetrical 2B type, indicating that the chromosomes of progenies are primitive.

Karyotype Comparison of F_1 and F_2 Hybrids of Sugarcane and Erianthus fulvus

Chromosome specimens of sugarcane, Erianthus fu/vus and their progenies were prepared with wall degradation hypotonic method to analyze the karyotypes of parents and Fl, F2 hybrids. The results showed that most chromosomes of experimental materials are median region （m） chromosomes, while only a small amount of chromosomes are submedian （sm） chromosomes. The karyotype of YAU04/102 belongs to 2C type, while other materials belong to 2B type. In addition, the karyotypes of hybrids are asymmetrical and the chromosomes of hybrids show an evolutionary trend compared with parental chromosomes.

Evaluation of Cold Tolerance in Wild Sugarcane Germplasm Resources under Field Conditions

In January 2016, Kunming underwem 52 hours of rain and snow weather below 0℃. in order to identify the cold tolerance of different wild sugarcane germplasm resources in low temperature and snow disasters, cold injuries of 38 shares of wild sugareane germplasm resources, which were oollected during 2012 -2013 and preserved in the germplasm resource nursery of Sugarcane Research Institute, Yumlan Agricultural University, were surveyed to evaluate the cold tolerance based on sugarcanc cold tolerance index （CTI） = 0.5 x shoot tip growing point injury index ＋ O. 3 x node injury index ＋ 0.2X internode injury in- dex. The results showed that cold tolerance indexes of four wild sugarcane varieties demonstrated a descending order of Erianthus arundinaceum Retz. （0.7）, Eri- aTrthus rockii Keng （0.5） , Sacchartun sporrtanettm L. （0.3） , Erianlhus fulvus Ne^s. （0）. Greater cold tolerance indexes indicate poorer cold tolerance. Thus, Erianthu, arundinaceum had the poorest cold tolerance, while Erianthus fulvus exhibited the strongest cold tolerance. In addition, there were significant differences in cold tolerance among diffcrent Saccharum spontaneum clones. The 23 Saccharum spontaneum clones could be divided into four grades, including 1 clone with the poorest cold tolerance that accounted for 4.3%, 5 clones with poor cold tolerance that accounted for 21.7%, 14 clones with strong cold tolerance that accounted tot 60.9%, and 3 clones with the strongest cold tolerance that accounted for 13.0% （2012 -23, 2012 -32, 2012 -37）. Especially, 2012 -23 exhibited extremely strong cold tolerance. This study provided the scientific basis for screening of cold-tolerant wild sugarcane germplasm resources and selection of cold-toleranl parents.

Wafer-level substrate-free YIG single crystal film for a broadband tunable terahertz isolator

Yttrium iron garnet(YIG)is a promising material for various terahertz applications due to its special optical properties.At present,a high-quality YIG wafer is the desire of terahertz communities and it is still challenging to prepare substrate-free YIG single crystal films.In this work,we prepared wafer-level substrate-free La:YIG single crystal films,for the first time,to our knowledge.Terahertz optical and magneto-optical properties of La:YIG films were characterized by terahertz time domain spectroscopy(THz-TDS).Results show that the as-prepared La:YIG film has an insertion loss of less than 3 dB and a low absorption coefficient of less than10 cm-1below 1.6 THz.Benefitting from the thickness of the substrate-free YIG films and low insertion loss,their terahertz properties could be further manipulated by simply using a wafer-stacking technique.When four La:YIG films were stacked,there was an insertion loss of less than 10 dB in the range of 0.1-1.2 THz.The Faraday rotation angle of the four-layer-stacked La:YIG films reached 19°,and the isolation could reach17 dB.By further increasing the stacking number to eight pieces,a remarkable Faraday rotation angle of45°was achieved with an isolation of 23 dB,which is important for practical application in the THz band.This material may provide a milestone opportunity to make various non-reciprocal devices,such as isolators and phase shifters.

A chromosome-level genome assembly for Erianthus fulvus provides insights into its biofuel potential and facilitates breeding for improvement of sugarcane

Erianthus produces substantial biomass,exhibits a good Brix value,and shows wide environmental adaptability,making it a potential biofuel plant.In contrast to closely related sorghum and sugarcane,Erianthus can grow in degraded soils,thus releasing pressure on agricultural lands used for biofuel production.However,the lack of genomic resources for Erianthus hinders its genetic improvement,thus limiting its potential for biofuel production.In the present study,we generated a chromosome-scale reference genome for Erianthus fulvus Nees.The genome size estimated by flow cytometry was 937 Mb,and the assembled genome size was 902 Mb,covering 96.26%of the estimated genome size.A total of 35065 proteincoding genes were predicted,and 67.89%of the genome was found to be repetitive.A recent wholegenome duplication occurred approximately 74.10 million years ago in the E.fulvus genome.Phylogenetic analysis showed that E.fulvus is evolutionarily closer to S.spontaneum and diverged after S.bicolor.Three of the 10 chromosomes of E.fulvus formed through rearrangements of ancestral chromosomes.Phylogenetic reconstruction of the Saccharum complex revealed a polyphyletic origin of the complex and a sister relationship of E.fulvus with Saccharum sp.,excluding S.arundinaceum.On the basis of the four amino acid residues that provide substrate specificity,the E.fulvus SWEET proteins were classified as monoand disaccharide sugar transporters.Ortho-QTL genes identified for 10 biofuel-related traits may aid in the rapid screening of E.fulvus populations to enhance breeding programs for improved biofuel production.The results of this study provide valuable insights for breeding programs aimed at improving biofuel production in E.fulvus and enhancing sugarcane introgression programs.

Enhanced performance of a fast GaAs-based terahertz modulator via surface passivation

Surface-modified semiconductors show enormous potential for opto-terahertz(THz)spatial modulation due to their enhanced modulation depth(MD)along with their inherent broad bandwidth.Taking full advantage of the surface modification,a performance-enhanced,all-optical,fast switchable THz modulator was achieved here based on the surface-passivated Ga As wafer.With a decreased surface recombination rate and prolonged carrier lifetime induced by passivation,S-passivated Ga As was demonstrated as a viable candidate to enhance THz modulation performance in MD,especially at low photodoping levels.Despite a degraded modulation rate owing to the longer carrier lifetime,this passivated Ga As modulator simultaneously realizes a fast modulation at a 69-MHz speed and as high an MD as ~94% in a spectral wideband of 0.2-1.2 THz.The results demonstrated a new strategy to alleviate the tradeoff between high MD and speed in contrast to bare surfaces or heterogeneous films/unusual geometry on semiconductors including Si,Ge,and GaAs.

Synthesis of yttrium iron garnet/bismuth quantum dot heterostructures with localized plasmon enhanced magneto-optical performance

Interactions between light and magnetic matter attracted great attention lately due to their potential applications in nanophotonics,spintronics,and high-accuracy sensing.Here,we grew bismuth quantum dots(Bi–QDs)with strong spin–orbit coupling on a magnetic insulator yttrium iron garnet(YIG)via molecular beam epitaxy.The YIG/Bi–QDs material shows an enhanced magneto-optical Kerr rotation up to 130%compared with that of a bare YIG film.The Bi–QDs were also introduced onto a lutetium–bismuth co-doped YIG film to form a hybrid system with remarkably enhanced Kerr rotation(from 1626 to 2341 mdeg).Ferromagnetic resonance measurements showed an increased effective magnetization as well as interfacial spin–orbit field in the YIG/Bi–QD heterostructures.Localized plasmons were mapped using electron energy loss spectroscopy with high spatial resolution,revealing enhanced plasmon intensity at both the Bi–QD surface and YIG/Bi–QD interface.Introducing Bi-QDs onto the YIG film enhanced Kerr rotation owing to the attenuated optical reflection and increased effective magnetization.The Bi–QDenhanced magneto-optical effect enables development of efficient nanoscale light switching,spintronics,and even plasmonic nano-antennas.