No abstract

Tomato is an edible and useful vegetable. Navel rot disease and low light stress are the problem in tomato cultivation. Tomato breeding is a potential cheap solution but takes longer time. Grafting technology provides instant solution like cultivating sensitive tomato (scion) grafted on resistant rootstock on non-optimal environmental conditions. DNA methylation of grafted plants might help to adapt to the adverse conditions and has become a hot point in researches concerning vegetable breeding. In this research, disease-resistant tomato cultivar "1221" was used as rootstock, while disease-sensitive tomato cultivar "Money Maker (MM)" was used as scion. After grafting, changes of genomic global DNA methylation were investigated through MSAP analysis. According to MSAP analysis, alterations of degree of DNA methylation patterns were observed, which might help graft hybrids to adapt in response to the internal and external stimuli.

Hessian fly is a global pest of wheat. Traditional control methods for this pest include implementing fly-free planting dates, stubble plow down and use of resistant cultivars. These methods face challenges due to changes in climate and cultural practice. Fly-free dates are no longer useful or need to be modified due to fly phenology shifts with increasing temperatures. Volunteer wheat destruction and stubble plow-down are no longer feasible due to the prevalence of no-till farming. Although plant resistance has been a cornerstone of fly management, many fly resistance genes lose effectiveness under higher temperatures. New fly-resistant genes effective under elevated temperatures need to be identified and markers for these genes developed. Advances in understanding of plant resistance mechanisms and fly attack mechanisms may result in novel technologies for Hessian fly control in the future, but the requisite molecular studies are still at very early stages and need to be strengthened.

Spring wheat (Triticum aestivum L.) is one of the most imperative staple food crops, with an annual production of 765 million tons globally to feed ∼40% world population. Genetic diversity in available germplasm is crucial for sustainable wheat improvement to ensure global food security. A diversity panel of 184 Pakistani wheat accessions was genotyped using 123,596 high-quality single nucleotide polymorphism (SNP) markers generated by genotyping-by-sequencing with 42% of the SNPs mapped on B, 36% on A, and 22% on D sub-genomes of wheat. Chromosome 2B contains the most SNPs (9,126), whereas 4D has the least (2,660) markers. The mean polymorphic information content, genetic diversity, and major allele frequency of the population were 0.157, 0.1844, and 0.87, respectively. Analysis of molecular variance revealed a higher genetic diversity (80%) within the sub-population than among the sub-populations (20%). The genome-wide linkage disequilibrium was 0.34 Mbp for the whole wheat genome. Among the three subgenomes, A has the highest LD decay value (0.29 Mbp), followed by B (0.2 Mbp) and D (0.07 Mbp) genomes, respectively. The results of population structure, principal coordinate analysis, phylogenetic tree, and kinship analysis also divided the whole population into three clusters comprising 31, 33, and 120 accessions in group 1, group 2, and group 3, respectively. All groups were dominated by the local wheat accessions. Estimation of genetic diversity will be a baseline for the selection of breeding parents for mutations and the genome-wide association and marker-assisted selection studies.