No abstract

Leaf color is one of the well-sought traits in breeding program for Anthurium andraeanum Lind. Knowledge of mechanisms in anthuriums to produce leaves with different shades of green would help to effectively select desirable traits. In this study, the micro- and ultra-structural and physiological features of leaves on wild type and leaf color mutants (dark green, rubescent, etiolated, albino) in A. andraeanum ‘Sonate’ were analyzed. Results show that chloroplasts of leaf color mutants exhibited abnormal morphology and distribution. Using next generation sequencing technology followed by de novo assembly, leaf transcriptomes comprising of 41,017 unigenes with an average sequence length of 768 bp were produced from wild type and rubescent mutant. From the 27,539 (67.1%) unigenes with annotated functions, 858 significantly differently expressed genes (DEGs) were identified, consisting of 446 up-regulated genes and 412 down-regulated genes. Genes that affect chloroplasts development and division, and chlorophyll biosynthesis were included in the down-regulated DEGs. Quantitative real-time PCR (qRT-PCR) analysis validated that the expression level of those genes was significantly lower in the rubescent, etiolated, and albino mutant compared to wild type plants, which concurs with the differences in micro- and ultra-structures and physiological features between these two types of plants. Conclusively, the leaf color formation is greatly affected by the activity of chloroplast development and pigment biosynthesis. And the possible formation pathway of leaf color mutant of A. andraeanum ‘Sonate’ is deduced based on our results.

cHere we completely sequenced four mcr-1-haboring plasmids, isolated from two extended-spectrum-␤-lactamase (ESBL)-producing Escherichia coli and two carbapenemase-producing Klebsiella pneumoniae clinical isolates. The mcr-1-harboring plasmids from an E. coli sequence type 2448 (ST2448) isolate and two K. pneumoniae ST25 isolates were identical (all pMCR1-IncX4), belonging to the IncX4 incompatibility group, while the plasmid from an E. coli ST2085 isolate (pMCR1-IncI2) belongs to the IncI2 group. A nearly identical 2.6-kb mcr-1-pap2 element was found to be shared by all mcr-1-carrying plasmids.T he plasmid-mediated colistin resistance gene, mcr-1, has recently been reported from animals and hospitalized patients in China (1). Since then, mcr-1 has been found in ϳ20 countries on four different continents (2). Alarmingly, mcr-1 has also been identified in several multidrug-resistant bacteria, including extended-spectrum-␤-lactamase (ESBL)-producing and carbapenemase-producing Enterobacteriaceae (CPE) (3-9). However, knowledge regarding the structure of mcr-1-harboring plasmids is limited. Here we completely sequenced four mcr-1-harboring plasmids (three of which are identical), isolated from two ESBLproducing Escherichia coli and two carbapenemase-producing Klebsiella pneumoniae clinical isolates (4).In a recent study, we identified mcr-1 in two ESBL-producing E. coli (SZ01 and SZ02) and two carbapenemase-producing K. pneumoniae (SZ03 and SZ04) clinical isolates from a tertiary hospital in eastern China (4). SZ01, SZ02, and SZ04 carry ESBL gene bla CTX-M-55 , while SZ03 and SZ04 harbor carbapenemase gene bla . Multilocus sequence typing (MLST) (10, 11) showed that the two E. coli isolates, SZ01 and SZ02, belong to two unrelated sequence types (STs) (ST2448 and ST2085), while the two K. pneumoniae strains (isolated from the same patient) both belong to ST25. The mcr-1-harboring plasmids from all four isolates were subsequently transferred to recipient strain E. coli J53 AZ r via conjugation, along with the bla NDM-5 -harboring plasmids from SZ03 and SZ04. Susceptibility testing revealed that the four mcr-1-harboring E. coli transconjugants were resistant to colistin but not to any of the other antimicrobial agents tested. The two bla transconjugants were resistant to all ␤-lactams, except for aztreonam, but remained susceptible to other classes of antimicrobial agents (data not shown). The mcr-1-and bla NDM-5 -harboring plasmids from these transconjugants were extracted and subjected to sequencing using the Illumina MiSeq platform (12). The sequencing reads were assembled de novo using SPAdes (13), and gaps were closed by standard PCR and Sanger sequencing as described previously (12).The mcr-1-harboring plasmids from SZ01, SZ03, and SZ04 (subsequently named pMCR1-IncX4) were all identical, belonging to the IncX4 incompatibility group, and were 33,287 bp in length with a GϩC content of 41.8%. The backbone of pMCR1-IncX4 is similar to that of other IncX4 plasmids, including pJIE143 (GenBank accession no. JN194214...

In rice (Oryza sativa), amylose content (AC) is the major factor that determines eating and cooking quality (ECQ). The diversity in AC is largely attributed to natural allelic variation at the Waxy (Wx) locus. Here we identified a rare Wx allele, Wxmw, which combines a favorable AC, improved ECQ and grain transparency. Based on a phylogenetic analysis of Wx genomic sequences from 370 rice accessions, we speculated that Wxmw may have derived from recombination between two important natural Wx alleles, Wxin and Wxb. We validated the effects of Wxmw on rice grain quality using both transgenic lines and near‐isogenic lines (NILs). When introgressed into the japonica Nipponbare (NIP) background, Wxmw resulted in a moderate AC that was intermediate between that of NILs carrying the Wxb allele and NILs with the Wxmp allele. Notably, mature grains of NILs fixed for Wxmw had an improved transparent endosperm relative to soft rice. Further, we introduced Wxmw into a high‐yielding japonica cultivar via molecular marker‐assisted selection: the introgressed lines exhibited clear improvements in ECQ and endosperm transparency. Our results suggest that Wxmw is a promising allele to improve grain quality, especially ECQ and grain transparency of high‐yielding japonica cultivars, in rice breeding programs.