Overexpression of PGA37/MYB118 and MYB115 promotes vegetative-to-embryonic transition in Arabidopsis

Formation of somatic embryos from non-germline cells is unique to higher plants and can be manipulated in a variety of species. Previous studies revealed that overexpression of several Arabidopsis genes, including WUSCHEL （WUS）/PLANT GROWTH ACTIVATOR6 （PGA6）, BABY BOOM, LEAFY COTYLEDON1 （LEC1）, and LEC2, is able to cause vegetative-to-embryonic transition or the formation of somatic embryos. Here, we report that a gain-offunction mutation in the Arabidopsis PGA37 gene, encoding the MYBI18 transcription factor, induced vegetative-toembryonic transition, the formation of somatic embryos from root explants, and an elevated LEC1 expression level. Double mutant analysis showed that WUS was not required for induction of somatic embryos by PGA37/MYB118. In addition, overexpression of MYBll5, a homolog of PGA37/MYB118, caused a pga37-like phenotype. A myb118 myb115 double mutant did not show apparent developmental abnormalities. Collectively, these results suggest that PGA37/ MYB118 and MYB115 promote vegetative-to-embryonic transition, through a signaling pathway independent of WUS.

ASYMPTOTICS OF THE SOLUTIONS TO STOCHASTIC WAVE EQUATIONS DRIVEN BY A NON-GAUSSIAN LéVY PROCESS

In this article, we consider the long time behavior of the solutions to stochastic wave equations driven by a non-Gaussian Lévy process. We shall prove that under some appropriate conditions, the exponential stability of the solutions holds. Finally, we give two examples to illustrate our results.

Rapid generation of genetic diversity by multiplex CRISPR/Cas9 genome editing in rice

The clustered regularly interspaced short palindromic repeats(CRISPR)-associated endonuclease 9(CRISPR/Cas9) system has emerged as a promising technology for specific genome editing in many species. Here we constructed one vector targeting eight agronomic genes in rice using the CRISPR/Cas9 multiplex genome editing system. By subsequent genetic transformation and DNA sequencing, we found that the eight target genes have high mutation efficiencies in the T_0 generation. Both heterozygous and homozygous mutations of all editing genes were obtained in T_0 plants. In addition, homozygous sextuple, septuple, and octuple mutants were identified. As the abundant genotypes in T_0 transgenic plants, various phenotypes related to the editing genes were observed. The findings demonstrate the potential of the CRISPR/Cas9 system for rapid introduction of genetic diversity during crop breeding.

Characterization and Fine Mapping of a Novel Rice Narrow Leaf Mutant nal9

A narrow leaf mutant was isolated from transgenic rice （Oryza sativa L.） lines carrying a T-DNA insertion. The mutant is characterized by narrow leaves during its whole growth period, and was named nal9 （narrow leaf 9）. The mutant also has other phenotypes, such as light green leaves at the seedling stage, reduced plant height, a small panicle and increased tillering. Genetic analysis revealed that the mutation is controlled by a single recessive gene. A hygromycin resistance assay showed that the mutation was not caused by T-DNA insertion, so a map-based cloning strategy was employed to isolate the nal9 gene. The mutant individuals from the F2 generations of a cross between the nal9mutant and Longtepu were used for mapping. With 24 F2 mutants, the nal9 gene was preliminarily mapped near the marker RM156 on the chromosome 3. New INDEL markers were then designed based on the sequence differences between japonica and indica at the region near RM156. The nal9 gene was finally located in a 69.3 kb region between the markers V239B and V239G within BAC OJ1212_C05 by chromosome walking. Sequence and expression analysis showed that an ATP-dependent CIp protease proteolytic subunit gene （CIpP） was most likely to be the nal9 gene. Furthermore, the nal9 mutation was rescued by transformation of the CIpP cDNA driven by the 35S promoter. Accordingly, the CIpP gene was identified as the NAL9 gene. Our results provide a basis for functional studies of NAL9 in future work.

Multi-omics analyses of 398 foxtail millet accessions reveal genomic regions associated with domestication,metabolite traits,and antiinflammatory effects

Foxtail millet(Setaria italica),which was domesticatedfromthewild speciesgreenfoxtail(Setaria viridis),isa richsource of phytonutrientsfor humans.To evaluate how breeding changed themetabolome offoxtail millet grains,we generated and analyzed the datasets encompassing the genomes,transcriptomes,metabolomes,and anti-inflammatory indices from 398 foxtail millet accessions.We identified hundreds of common variants that influence numerous secondary metabolites.We observed tremendous differences in natural variations of the metabolites and their underlying genetic architectures between distinct sub-groups of foxtail millet.Furthermore,we found that the selection of the gene alleles associated with yellow grains led to altered profiles of metabolites such as carotenoids and endogenous phytohormones.Using CRiSPR-mediated genome editing wevalidated the function of PHYTOENE SYNTHASE1(PSY1)gene in affecting milletgrain colorand quality.Interestingly,our in vitro cell inflammation assays showed that 83 metabolites in millet grains have anti-inflammatory effects.Taken together,ourmulti-omics study illustrates how the breeding history of foxtail millet has shaped its metabolite profile.The datasets we generated in this study also provide important resources for further understanding how millet grain quality is affected by different metabolites,laying the foundations for future millet genetic research and metabolome-assisted improvement.

Foxtail millet:nutritional and eating quality,and prospects for genetic improvement

Foxtail millet is a minor yet important crop in some areas of the world,particularly northern China.It has strong adaptability to abiotic stresses,especially drought,and poor soil.It also has high nutritional value.Foxtail millet is rich in essential amino acids,fatty acids and minerals,and is considered to be one of the most digestible and non-allergenic grains available and has significant importance for human health.Given foxtail millet’s ability to adapt to abiotic stresses associated with climate change,it is more important than ever to develop breeding strategies that facilitate the increasing demand for high quality grain that better satisfies consumers.Here we review research on foxtail millet quality evaluation,appearance,cooking and eating quality at the phenotypic level.We review analysis of the main nutrients in foxtail millet,their relationships and the biochemical and genetic factors affecting their accumulation.In addition,we review past progress in breeding this regionally important crop,outline current status of breeding of foxtail millet,and make suggestions to improve grain quality.

Application of TEM Based on HTS SQUID Magnetometer in Deep Geological Structure Exploration in the Baiyun Gold Deposit,NE China

Exploration of deep mineralization,particularly where the mineralization of interest is covered by a conductive overburden,is still a challenge for the conventional transient electromagnetic(TEM)method,which measures TEM response using induction coils as the sensor.However,sensors such as fluxgate and superconductive quantum interfere device(SQUID)magnetometers can measure the B-field directly,which can provide more reliable deep information for mineralization exploration.In this paper,we report on the research and development of our newly developed high-temperature su-perconductor(HTS)SQUID magnetometer,which is cooled by liquid nitrogen at 77 K,and its applica-tion in TEM measurement for deep exploration in a gold deposit in China.This improved SQUID magnetometer version has a good performance with noise(60 fT/√Hz),slew rate(0.8 mT/S),dynamic range(100 dB),sensitivity(6.25 mV/nT),and bandwidth(DC-20 kHz).To find deep and peripheral ore in the Baiyun gold deposit located in Liaoning Province,NE China,both the SQUID magnetometer and induction coil were used for TEM data acquisition.Results show that TEM can detect the distribution of local strata and the faults contained within them.Results also indicate that the SQUID magnetome-ter has superior response performance for response over geological targets with slower decay time when compared to the induction coil signals.The SQUID magnetometer is more sensitive at observing the induced-polarization effect which is closely related to the ore-controlling faults.

Deletion of the Initial 45 Residues of ARR18 Induces Cytokinin Response in Arabidopsis

The plant hormone cytokinin plays important roles in various aspects of plant growth and development. Cytokinin signaling is mediated by a multistep phosphorelay similar to bacterial two-component system. Type-B ARRs lie at the end of the cytokinin signaling, typically mediating tile output response. However, it is still unclear how type-B ARRs are regulated in response to cytokinin. Typical type-B ARR contains an N-terminal receiver domain and a C-terminal effector domain. In this study, we performed a genome-wild comparative analysis by overexpressing full length and C-terminal effector domain of seven representative type-B ARRs. Our results indicated that overexpression of C-terminal effector domain causes short primary roots and short hypocotyls without the addition of cytokinin, sug- gesting that the inhibitory role of the receiver domain in the activity of the effector domain is a common mechanism in type-B ARRs. To investigate how the receiver domain inhibits the activity of the effector domain, we performed a deletion analysis. We found that deletion of the initial 45 residues of ARR18 （the 45 residues from N-terminus） causes pleiotropic growth defects by directly inducing cytokinin responsive genes. Together, our results suggest that the initial 45 residues are critical for the inhibitory role of the receiver domain to the effector domain in ARRI8.

Inversion of IP-Affected TEM Responses and Its Application in High Polarization Area

The transient electromagnetic(TEM)responses measured in areas with highly pola-rizable media commonly show induced polarization(IP)effects,which poses difficulties to the TEM data interpretation and inversion with conventional methods.When present,the IP effects break the monotony in TEM decay curves and can even cause sign reversals,and lead to the singularity and non-monotony of inversion method.It is therefore important to take the IP effects into account when processing those TEM data.In this paper,a new inversion method is developed to invert TEM data with IP effects.The Cole-Cole model was introduced to the forward modeling solver so that the IP effects can be accurately calculated.The regularization terms were adapted to the objective function and a global optimization method,the particle swarm optimization algorithm,was used to solve the optimization problem,which weakened the singularity and non-monotony of the inversion greatly.Field data were collected in Wulong gold mine where IP effects were detected.The data were in-verted using the method developed in this paper,and the inversion results were able to identify the depth extension of NO.163 ore-bearing quartz veins and their associated fine-grained diorite veins.The global inversion method in this paper primarily solved the inversion problem of IP-affected TEM responses,and recovered the polarization parameters,which can be used as an aid to the geo-logical interpretation.

Erratum to: Rapid generation of genetic diversity by multiplex CRISPR/Cas9 genome editing in rice

The same figure was misused for the PCR/RE assay results of Gn1a and GW2 fragments in Figure 3,and the arrows in the graphicsal result of GW2 were not on the tape.The corrected Figure 3 is as follows.

Plant genetic engineering and genetically modified crop breeding: history and current status

This review charts the major developments in the genetic manipulation of plant cells that have taken place since the first gene transfer experiments using Ti plasmids in 1983. Tremendous progress has been made in both our scientific understanding and technological capabilities since the first genetically modified(GM)crops were developed with single gene resistances to herbicides, insects, viruses, and the silencing of undesirable genes. Despite opposition in some parts of the world, the area planted with first generation GM crops has grown from 1.7 Mhm^2 in 1996 to 179.7 Mhm^2 in 2015.The toolkit available for genetic modification has expanded greatly since 1996 and recently Nobel Laureates have called on Greenpeace to end their blanket opposition,and plant scientists have urged that consideration be given to the benefits of GM crops based on actual evidence. It is now possible to use GM to breed new crop cultivars resistant to a much wider range of pests and diseases, and to produce crops better able to adapt to climate change.The advent of new CRISPR-based technologies makes it possible to contemplate a much wider range of improvements based on transfer of new metabolic pathways and traits to improve nutritional quality, with a much greater degree of precision. Use of GM, sometimes in conjunction with other approaches, offers great opportunities for improving food quality, safety, and security in a changing world.

The Arabidopsis BE1 Gene,Encoding a Putative Glycoside Hydrolase Localized in Plastids,Plays Crucial Roles during Embryogenesis and Carbohydrate Metabolism

Carbohydrate metabolism is central to plant growth and development. However, little is known about its role in embryogenesis. Here, we report the characterization of multiple alleles of the BRANCHING ENZYME1 （BE1） gene （also known as EMB2729）. The weak allele of be1-3, characterized by positional cloning, carries a single-nucleotide substitution in an exon-intron junction and shows various developmental defects during post-germination growth. This mutation causes a reduced level of BE1 mRNA that, likely generated from cryptically spliced pre-mRNA, contains a Glu-to-Lys substitution at codon 366. In four null alleles, BE1 is disrupted by T-DNA insertions, causing embryo developmental arrests at the heart stage. Light microscopy reveals reduced cell divisions and abnormal cell differentiation, thereby leading to defects in setting up the shoot apical meristem, embryonic vascular tissues and cotyledons. Overexpression of BE1 results in a pleiotropic phenotype, indicating that the fine-tuned BE1 level is crucial for plant growth and development. BE1 encodes a putative glycoside hydrolase that is highly conserved in higher plants. A BE1-GFP fusion protein, which is fully functional in complementing be1 mutants, is localized in plastids. The be1-3 phenotype can be partially rescued by glucose, fructose or sucrose, implying the involvement of BE1 in carbohydrate metabolism in plastids.