Ectopic Overexpression of EuCHIT30.7 Improves Nicotiana tabacum Resistance to Powdery Mildew

Various strains of powdery mildew(PM),a notorious plant fungal disease,are prevalent and pose a significant threat to plant health.To control PM,transgenic technology can be used to cultivate more resistant plant varieties.In the present study,we utilized the rapid amplification of cDNA ends(RACE)technique to clone the full-length cDNA sequence of the EuCHIT30.7 gene to explore plant genes with disease resistance functions.Bioinformatics analysis revealed that this gene belongs to the GH18 family and is classified as a class III chitinase.The EuCHIT30.7 gene is expressed throughout the Eucommia ulmoides plant,with the most abundant expression in male flowers.Subcellular localization analysis indicated that the protein encoded by this gene was detected within both the cell membrane and cytoplasm.Upon PM inoculation,overexpression of EuCHIT30.7 in tobacco plants led to a significantly reduced relative lesion area and a decreased spore count compared to both wild-type and empty vector control plants.Activities of the protective enzymes,namely,peroxidase(POD),superoxide dismutase(SOD),catalase(CAT),and phenylalaninammo-nialyase(PAL),in tobacco plants overexpressing EuCHIT30.7 were significantly greater than those in wild-type and empty vector tobacco plants.Furthermore,the rate of increase in malondialdehyde(MDA)content was significantly lower in tobacco plants expressing EuCHIT30.7 compared to control tobacco plants.In EuCHIT30.7 transgenic tobacco,the expression of pathogen-related protein genes,namely,PR2,PR5,PR1a,PDF1.2,and MLP423,along with the tobacco PM negative regulatory gene,MLO2,were significantly higher compared to control tobacco plants.These findings suggested that EuCHIT30.7 significantly enhances the resistance of tobacco to PM.

Comparative and population genomics of buckwheat species reveal key determinants of flavor and fertility

Common buckwheat(Fagopyrum esculentum)is an ancient crop with a world-wide distribution.Due to its excellent nutritional quality and high economic and ecological value,common buckwheat is becoming increasingly important throughout the world.The availability of a high-quality reference genome sequence and population genomic data will accelerate the breeding of common buckwheat,but the high heterozygosity due to the outcrossing nature has greatly hindered the genome assembly.Here we report the assembly of a chromosome-scale high-quality reference genome of F.esculentum var.homotropicum,a homozygous self-pollinating variant of common buckwheat.Comparative genomics revealed that two cultivated buckwheat species,common buckwheat(F.esculentum)and Tartary buckwheat(F.tataricum),underwent metabolomic divergence and ecotype differentiation.The expansion of several gene families in common buckwheat,including FhFAR genes,is associated with its wider distribution than Tartary buckwheat.Copy number variation of genes involved in the metabolism of flavonoids is associated with the difference of rutin content between common and Tartary buckwheat.Furthermore,we present a comprehensive atlas of genomic variation based on whole-genome resequencing of 572 accessions of common buckwheat.Population and evolutionary genomics reveal genetic variation associated with environmental adaptability and floral development between Chinese and non-Chinese cultivated groups.Genome-wide association analyses of multi-year agronomic traits with the content of flavonoids revealed that Fh05G014970 is a potential major regulator of flowering period,a key agronomic trait controlling the yield of outcrossing crops,and that Fh06G015130 is a crucial gene underlying flavor-associated flavonoids.Intriguingly,we found that the gene translocation and sequence variation of FhS-ELF3 contribute to the homomorphic self-compatibility of common buckwheat.Collectively,our results elucidate the genetic basis of speciation,ecological adaptation,fertility,and unique flavor of common buckwheat,and provide new resources for future genomics-assisted breeding of this economically important crop.

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.

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.