Genetic improvement of the cultivars of jute (Corchorus olitorius L. and Corchorus capsularis L.) is needed to broaden the genetic base of new cultivars. All the cultivars in use have been evolved through pure line selection from a few common accessions. The objective of this study was to evaluate the genetic diversity available in the cultivated species of jute. Genetic diversity was evaluated by simple sequence repeat (SSR) marker loci and an AFLP assay. A total of 305 polymorphic products were detected by AFLP analysis using 10 pairs of primers (EcoRI and MseI) to amplify template DNA from 49 genotypes of the two jute species. Additionally, polymorphism with two to four allelic lengths was detected with each pair of chloroplast microsatellite primers developed from Nicotiana tabacum L. Results from both evaluations showed that the level of variation between species is high. The two species indeed are distantly related and their maternal origins may be different. On the contrary, genetic variability present at the intraspecific level is low. The resulting dendrogram showed common ancestral origin for many accessions. A few major Indian cultivars of both the species, used as an internal check, were closely related to the wild accessions. Nevertheless, RG, an Indian accession and two Kenyan accessions, KEN/BL/17 and KEN/DS/35C, among the C. olitorius genotypes and CHN/FJ/69 of C. capsularis revealed phenetic distinctiveness from the rest of the genotypes studied. The results indicate that enough diversity exists to broaden the genetic base of new jute cultivars.

Southern crabgrass [Digitaria ciliaris (Retz.) Koeler] is an annual grass weed that commonly infests turfgrass, roadsides, wastelands, and cropping systems throughout the southeastern United States. Two biotypes of D. ciliaris (R1 and R2) with known resistance to cyclohexanediones (DIMs) and aryloxyphenoxypropionates (FOPs) previously collected from sod production fields in Georgia were compared with a separate susceptible biotype (S) collected from Alabama for the responses to pinoxaden and to explore the possible mechanisms of resistance. Increasing rates of pinoxaden (0.1 to 23.5 kg ha−1) were evaluated for control of R1, R2, and S. The resistant biotypes, R1 and R2, were resistant to pinoxaden relative to S. The S biotype was completely controlled at rates of 11.8 and 23.5 kg ha−1, resulting in no aboveground biomass at 14 d after treatment. Pinoxaden rates at which tiller length and aboveground biomass would be reduced 50% (I50) and 90% (I90) for R1, R2, and S ranged from 7.2 to 13.2 kg ha−1, 6.9 to 8.6 kg ha−1, and 0.7 to 2.1 kg ha−1, respectively, for tiller length, and 7.7 to 10.2 kg ha−1, 7.2 to 7.9 kg ha−1, and 1.6 to 2.3 kg ha−1, respectively, for aboveground biomass. Prior selection pressure from DIM and FOP herbicides could result in the evolution of D. ciliaris cross-resistance to pinoxaden herbicides. Amplification of the carboxyl-transferase domain of the plastidic ACCase by standard PCR identified a point mutation resulting in an Ile-1781-Leu amino acid substitution only for the resistant biotype, R1. Further cloning of PCR product surrounding the 1781 region yielded two distinct ACCase gene sequences, Ile-1781 and Leu-1781. The amino acid substitution, Ile-1781-Leu in both resistant biotypes (R1 and R2), however, was revealed by next-generation sequencing of RNA using Illumina platform. A point mutation in the Ile-1781 codon leading to herbicide insensitivity in the ACCase enzyme has been previously reported in other grass species. Our research confirms that the Ile-1781-Leu substitution is present in pinoxaden-resistant D. ciliaris.

Miscanthus is increasingly gaining popularity as a bioenergy grass because of its extremely high biomass productivity. Many clones of this grass were introduced into United States over the past century from East Asia where it originated, and planted for ornamental and landscaping purposes. An understanding of the genetic diversity among these naturalized populations may help in the efficient selection of potential parents in the Miscanthus breeding program. Here, we report our study analyzing the genetic diversity of 228 Miscanthus DNA samples selected from seven sites in six states (Ohio, North Carolina, Washington D.C., Kentucky, Pennsylvania, and Virginia) across the eastern United States. Ten transferable DNA markers from other plant species were employed to amplify genomic DNA of Miscanthus because of the paucity of molecular markers in Miscanthus. There were significant genetic variations observed within and among US naturalized populations. The highest genetic diversity (0.3738) was found among the North Carolina genotypes taken from Biltmore Deer Park and Biltmore, Madison County, Cody Rd. The lowest genetic diversity (0.2776) was observed among Virginia genotypes that were diverged from those from other states, suggesting Virginia genotypes might be independently introduced into the United States from the different origin. By the cluster and structure analysis, 228 genotypes were categorized into two major groups that were further divided into six subgroups at the DNA level and the groups were generally consistent with geographic region.

a few common accessions. It has also been indicated that each of the two jute species contain very limited genetic

BACKGROUND: Paraquat is used widely as one of the bipyridine herbicides, which generates reactive oxygen species to cause cell death. With a growing number of paraquat-resistant weeds, the mechanism of paraquat-resistance in plants remains unclear. This research verified the functions of a previously confirmed putative paraquat-resistant gene, EiKCS, from paraquat-resistant goosegrass by genetic engineering in a single overexpressing line in rice.RESULTS: Overexpression of EiKCS improved paraquat resistance in transgenic rice (KCSox). Pre-applied (12 h) exogenous spermidine (1.5 mmol L −1 ), alleviated the injury of paraquat in rice. Paraquat induced injury in KCSox was 19.57%, which was lower than 32.22% injury it induced in wild-type (WT) rice. The paraquat-resistant mechanism was through the increased activity of antioxidant enzymes and the overproduction of endogenous polyamines. The spermine content in KCSox was more than 30 ∼g mL −1 , while that in WT rice was less than 5 ∼g mL −1 . Quantitative proteomics showed that ⊎-ketoacyl-coenzyme A (CoA) synthase ( 51.81 folds) encoded by the transgenic EiKCS gene promoted the synthesis of the proteins involved with the polyamine pathway. The synthesized putrescine was promoted by the arginine decarboxylase (ADC) pathway. The spermidine synthase I (1.10-fold) and three eceriferum cofactors (CERs) were responsive to the paraquat stress. We validated putrescine (C 18 H 20 N 2 O 2 ) spermidine (C 28 H 31 N 3 O 3 ), and spermine (C 38 H 42 N 4 O 4 ) in this study.CONCLUSION: EiKCS encoding ⊎-ketoacyl-CoA synthase from goosegrass has been shown as an ideal candidate gene for engineering genetically modified organism (GMO) crops, as its overexpression does not only bring paraquat-resistance, but also have potential benefits without decreasing yield and rice grain quality.