Differential selection of yield and quality traits has shaped genomic signatures of cowpea domestication and improvement.

Cowpeas (tropical legumes) are important in ensuring food and nutritional security in developing countries, especially in sub-Saharan Africa. Herein, we report two high-quality genome assemblies of grain and vegetable cowpeas and we re-sequenced 344 accessions to characterize the genomic variations landscape. We identified 39 loci for ten important agronomic traits and more than 541 potential loci that underwent selection during cowpea domestication and improvement. In particular, the synchronous selections of the pod-shattering loci and their neighboring stress-relevant loci probably led to the enhancement of pod-shattering resistance and the compromise of stress resistance during the domestication from grain to vegetable cowpeas. Moreover, differential selections on multiple loci associated with pod length, grain number per pod, seed weight, pod and seed soluble sugars, and seed crude proteins shaped the yield and quality diversity in cowpeas. Our findings provide genomic insights into cowpea domestication and improvement footprints, enabling further genome-informed cultivar improvement of cowpeas.

Genome-wide association analysis reveals the optimal genomic regions for pod size in bean.

The snap bean is the most commonly grown vegetable legume worldwide, and its pod size is both an important yield and appearance quality trait. However, the improvement of pod size in snap beans grown in China has been largely hindered by a lack of information on the specific genes that determine pod size. In this study, we identified 88 snap bean accessions and evaluated their pod size traits. Through a genome-wide association study (GWAS), 57 single nucleotide polymorphisms (SNPs) significantly associated with pod size were detected. Candidate gene analysis showed that cytochrome P450 family genes, WRKY, and MYB transcription factors were the predominant candidate genes for pod development, and eight of these 26 candidate genes showed relatively higher expression patterns in flowers and young pods. A significant pod length (PL) SNP and a single pod weight (SPW) SNP were successfully converted into kompetitive allele-specific polymerase chain reaction (KASP) markers and validated in the panel. These results enhance our understanding of the genetic basis of pod size, and also provide genetic resources for the molecular breeding of pod size in snap beans.

RNA-Seq Identification of Cd Responsive Transporters Provides Insights into the Association of Oxidation Resistance and Cd Accumulation in Cucumis sativus L.

Greenhouse vegetable production (GVP) has grown rapidly and has become a major force for cucumber production in China. In highly intensive GVP systems, excessive fertilization results in soil acidification, increasing Cd accumulation and oxidative stress damage in vegetables as well as increasing health risk of vegetable consumers. Therefore, enhancing antioxidant capacity and activating the expression level of Cd transporter genes seem to be feasible solutions to promote plant resistance to Cd stress and to reduce accumulated Cd concentration. Here, we used transcriptomics to identify five cucumber transporter genes (CsNRAMP1, CsNRAMP4, CsHMA1, CsZIP1, and CsZIP8) in response to cadmium stress, which were involved in Cd transport activity in yeast. Ionomics, gene expression, and REDOX reaction level association analyses have shown that the transcript of CsNRAMP4 was positively correlated with Cd accumulation and antioxidant capacity of cucumber roots. The expression level of CsHMA1 was negatively correlated with Cd-induced antioxidant capacity. The overexpression of CsHMA1 significantly relieved Cd stress-induced antioxidant activities. In addition, shoots with high CsHMA2 expression remarkably presented Cd bioaccumulation. Grafting experiments confirmed that CsHMA1 contributed to the high antioxidant capacity of cucumber, while CsHMA2 was responsible for the transport of Cd from the roots to the shoots. Our study elucidated a novel regulatory mechanism for Cd transport and oxidative damage removal in horticultural melons and provided a perspective to regulate Cd transport artificially by modulating Cd accumulation and resistance in plants.

A novel ferrocenyl-naphthalimide as a multichannel probe for the detection of Cu(ii) and Hg(ii) in aqueous media and living cells.

A novel ferrocenyl-naphthalimide multichannel probe 1 was designed and synthesized using a facile method. The color of the solution containing probe 1 changed from yellow to colorless upon the addition of Cu2+ or Hg2+. Interestingly, probe 1 exhibited highly selective fluorescent turn-on for Cu2+ and turn-off for Hg2+ in aqueous solution. Probe 1 was an electrochemical Cu2+ and Hg2+ ion sensor, in which the Fc/Fc+ redox couple was significantly shifted (ΔE1/2 = 178 mV and ΔE1/2 = 53 mV, respectively) upon complexation. Therefore, probe 1 can act as a naked-eye chemosensor, as well as an electrochemical and a fluorescent probe for Cu2+ and Hg2+. Furthermore, this is the first reported probe that can be used for the bifunctional fluorescent detection of intracellular Cu2+ and Hg2+ by fluorescent imaging studies. These characteristics give this probe considerable potential in the study and analysis of Cu2+ and Hg2+ in complex biosystems.

Copper-catalyzed direct alkylation of 1,3-azoles with N-tosylhydrazones bearing a ferrocenyl group: a novel method for the synthesis of ferrocenyl-based ligands.

Copper-catalyzed cross-coupling of ferrocenyl ketone-derived N-tosylhydrazones with benzo[d]oxazole leads to the direct C-H bond functionalization by a secondary ferrocenyl alkyl group. This direct C-H bond alkylation of azoles with N-tosylhydrazones bearing a ferrocenyl group uses inexpensive CuBr as the catalyst without any ligand. The reaction is operationally simple and conducted under mild conditions, giving the corresponding ferrocenyl-based ligands in moderate to good yields. Furthermore, they were able to act as bidentate ligands, giving rise to the corresponding palladium chelated complex 6a-6c, which were obtained by reaction of 5a-5c with [PdCl2(MeCN)2].