On edge domination numbers of graphs

AbstractLet γs′(G) and γss′(G) be the signed edge domination number and signed star domination number of G, respectively. We prove that 2n-4⩾γss′(G)⩾γs′(G)⩾n-m holds for all graphs G without isolated vertices, where n=|V(G)|⩾4 and m=|E(G)|, and pose some problems and conjectures

On mixed Ramsey numbers

AbstractFor a graph theoretic parameter f, an integer m and a graph H, the mixed Ramsey number v(f; m; H) is defined as the least positive integer p such that if G is any graph of order p, then either f(G)⩾m or Ḡ contains a subgraph isomorphic to H. Let ϱ denote vertex linear arboricity and let H be any connected graph of order n. In this note we show that v(ϱ; m; H) = 1 + (n + np(H) − 2)(m − 1), where np(H) is the path partition number of H

A new characterization of fuzzy ideals of semigroups and its applications

In this paper, we develop a new technique for constructing fuzzy ideals of a semigroup. By using generalized Green\u27s relations, fuzzy star ideals are constructed. It is shown that the new fuzzy ideal of a semigroup can be used to investigate the relationship between fuzzy sets and abundance and regularity for an arbitrary semigroup. Appropriate examples of such fuzzy ideals are given in order to illustrate the technique. Finally, we explain when a semigroup satisfies conditions of regularity

Genomic regions, cellular components and gene regulatory basis underlying pod length variations in cowpea (V. unguiculata L. Walp).

Cowpea (V. unguiculata L. Walp) is a climate resilient legume crop important for food security. Cultivated cowpea (V. unguiculata L) generally comprises the bushy, short-podded grain cowpea dominant in Africa and the climbing, long-podded vegetable cowpea popular in Asia. How selection has contributed to the diversification of the two types of cowpea remains largely unknown. In the current study, a novel genotyping assay for over 50 000 SNPs was employed to delineate genomic regions governing pod length. Major, minor and epistatic QTLs were identified through QTL mapping. Seventy-two SNPs associated with pod length were detected by genome-wide association studies (GWAS). Population stratification analysis revealed subdivision among a cowpea germplasm collection consisting of 299 accessions, which is consistent with pod length groups. Genomic scan for selective signals suggested that domestication of vegetable cowpea was accompanied by selection of multiple traits including pod length, while the further improvement process was featured by selection of pod length primarily. Pod growth kinetics assay demonstrated that more durable cell proliferation rather than cell elongation or enlargement was the main reason for longer pods. Transcriptomic analysis suggested the involvement of sugar, gibberellin and nutritional signalling in regulation of pod length. This study establishes the basis for map-based cloning of pod length genes in cowpea and for marker-assisted selection of this trait in breeding programmes

The positive impacts of landscape fragmentation on the diversification of agricultural production in Zhejiang Province, China

Agricultural land fragmentation has an important impact on ecosystem services, especially food production. However, the relationship between land fragmentation and production diversification remains controversial and requires further analysis. This study characterized the dynamics of land fragmentation and production diversification in Zhejiang Province, China, from 1995 to 2015 using remote sensing, landscape metrics, and a diversification assessment approach. The results showed that Zhejiang Province experienced increasing fragmentation of agricultural landscapes and profound diversification of agricultural production. Fragmentation had a significant negative effect on grain crop production, but it had a significant positive effect on production diversification. These findings showed that fragmentation is an important driver of the diversification of agriculture and contributes to increased dietary diversity in local households. Therefore, we believe that when addressing land fragmentation issues, both the positive and negative impacts of fragmentation in different local conditions and circumstances should be taken into account. Our findings will provide scientific support for land consolidation management and agricultural land resource protection

Partial sequencing of the bottle gourd genome reveals markers useful for phylogenetic analysis and breeding

<p>Abstract</p> <p>Background</p> <p>Bottle gourd [<it>Lagenaria siceraria </it>(Mol.) Standl.] is an important cucurbit crop worldwide. Archaeological research indicates that bottle gourd was domesticated more than 10,000 years ago, making it one of the earliest plants cultivated by man. In spite of its widespread importance and long history of cultivation almost nothing has been known about the genome of this species thus far.</p> <p>Results</p> <p>We report here the partial sequencing of bottle gourd genome using the 454 GS-FLX Titanium sequencing platform. A total of 150,253 sequence reads, which were assembled into 3,994 contigs and 82,522 singletons were generated. The total length of the non-redundant singletons/assemblies is 32 Mb, theoretically covering ~ 10% of the bottle gourd genome. Functional annotation of the sequences revealed a broad range of functional types, covering all the three top-level ontologies. Comparison of the gene sequences between bottle gourd and the model cucurbit cucumber (<it>Cucumis sativus</it>) revealed a 90% sequence similarity on average. Using the sequence information, 4395 microsatellite-containing sequences were identified and 400 SSR markers were developed, of which 94% amplified bands of anticipated sizes. Transferability of these markers to four other cucurbit species showed obvious decline with increasing phylogenetic distance. From analyzing polymorphisms of a subset of 14 SSR markers assayed on 44 representative China bottle gourd varieties/landraces, a principal coordinates (PCo) analysis output and a UPGMA-based dendrogram were constructed. Bottle gourd accessions tended to group by fruit shape rather than geographic origin, although in certain subclades the lines from the same or close origin did tend to cluster.</p> <p>Conclusions</p> <p>This work provides an initial basis for genome characterization, gene isolation and comparative genomics analysis in bottle gourd. The SSR markers developed would facilitate marker assisted breeding schemes for efficient introduction of desired traits.</p

A SNP and SSR Based Genetic Map of Asparagus Bean (Vigna. unguiculata ssp. sesquipedialis) and Comparison with the Broader Species

Asparagus bean (Vigna. unguiculata ssp. sesquipedialis) is a distinctive subspecies of cowpea [Vigna. unguiculata (L.) Walp.] that apparently originated in East Asia and is characterized by extremely long and thin pods and an aggressive climbing growth habit. The crop is widely cultivated throughout Asia for the production of immature pods known as ‘long beans’ or ‘asparagus beans’. While the genome of cowpea ssp. unguiculata has been characterized recently by high-density genetic mapping and partial sequencing, little is known about the genome of asparagus bean. We report here the first genetic map of asparagus bean based on SNP and SSR markers. The current map consists of 375 loci mapped onto 11 linkage groups (LGs), with 191 loci detected by SNP markers and 184 loci by SSR markers. The overall map length is 745 cM, with an average marker distance of 1.98 cM. There are four high marker-density blocks distributed on three LGs and three regions of segregation distortion (SDRs) identified on two other LGs, two of which co-locate in chromosomal regions syntenic to SDRs in soybean. Synteny between asparagus bean and the model legume Lotus. japonica was also established. This work provides the basis for mapping and functional analysis of genes/QTLs of particular interest in asparagus bean, as well as for comparative genomics study of cowpea at the subspecies level