As there is a strong interest in red-skinned pears, the molecular mechanism of anthocyanin regulation in red-skinned pears has been widely investigated; however, little is known about the molecular mechanism of anthocyanin regulation in red-fleshed pears due to limited availability of such germplasm, primarily found in European pears (Pyrus communis).  In this study, based on transcriptomic analysis in red-fleshed and white-fleshed pears, we identified an ethylene response factor (ERF) from P. communis, PcERF5, of which expression level in fruit flesh was significantly correlated with anthocyanin content.  We then verified the function of PcERF5 in regulating anthocyanin accumulation by genetic transformation in both pear skin and apple calli.  PcERF5 regulated anthocyanin biosynthesis by different regulatory pathways.  On the one hand, PcERF5 can activate the transcription of flavonoid biosynthetic genes (PcDFR, PcANS and PcUFGT) and two key transcription factors encoding genes PcMYB10 and PcMYB114.  On the other hand, PcERF5 interacted with PcMYB10 to form the ERF5-MYB10 protein complex that enhanced the transcriptional activation of PcERF5 on its target genes.  Our results suggested that PcERF5 functioned as a transcriptional activator in regulating anthocyanin biosynthesis, which provides new insights into the regulatory mechanism of anthocyanin biosynthesis.  This new knowledge will provide guidance for molecular breeding of red-fleshed pear.

Rye (Secale cereale L., 2n=2x=14, RR) is a significant genetic resource for improving common wheat because of its resistance to multiple diseases and abiotic-stress tolerant traits.  The 1RS chromosome from the German cultivated rye variety Petkus is critical in wheat breeding.  However, its weakened disease resistance highlights the need to identify new resources.  In the present study, a novel derived line called D27 was developed from common wheat and Mexico Rye.  Cytological observations characterized the karyotype of D27 as 2n=42=21 II.  Genomic in situ hybridization indicated that a pair of whole-arm translocated Mexico Rye chromosomes were inherited typically in the mitotic and meiosis stages of D27.  Experiments using fluorescence in situ hybridization (FISH) and gliadin electrophoresis showed that D27 lacked wheat 1DS chromosomes.  They were replaced by 1RS chromosomes of Mexico Rye, supported by wheat simple-sequence repeat markers, rye sequence characterized amplified region markers, and wheat 40K SNP array analysis.  The wheat 1DS chromosomes could not be detected by molecular markers and wheat SNP array, but the presence of rye 1RS chromosomes was confirmed.  Agronomic trait assessments indicated that D27 had a higher tiller number and enhanced stripe rust and powdery mildew resistance.  In addition, dough properties analysis showed that replacing 1DS led to higher viscosity and lower dough elasticity in D27, which was beneficial for cake making.  In conclusion, the novel cytogenetically stable common wheat–Mexico Rye T1DL·1RS translocation line D27 offers excellent potential as outstanding germplasm in wheat breeding programs focusing on disease resistance and yield improvement.  Additionally, it can be valuable for researching the rye 1RS chromosome’s genetic diversity. 

The red coloring of pear fruits is mainly caused by anthocyanin accumulation.  Red sport, represented by the green pear cultivar ‘Bartlett’ (BL) and the red-skinned derivative ‘Max Red Bartlett’ (MRB), is an ideal material for studying the molecular mechanism of anthocyanin accumulation in pear.  Genetic analysis has previously revealed a quantitative trait locus (QTL) associated with red skin color in MRB.  However, the key gene in the QTL and the associated regulatory mechanism remain unknown.  In the present study, transcriptomic and methylomic analyses were performed using pear skin for comparisons between BL and MRB.  These analyses revealed differential PcHY5 DNA methylation levels between the two cultivars; MRB had lower PcHY5 methylation than BL during fruit development, and PcHY5 was more highly expressed in MRB than in BL.  These results indicated that PcHY5 is involved in the variations in skin color between BL and MRB.  We further used dual luciferase assays to verify that PcHY5 activates the promoters of the anthocyanin biosynthesis and transport genes PcUFGT, PcGST, PcMYB10 and PcMYB114, confirming that PcHY5 not only regulates anthocyanin biosynthesis but also anthocyanin transport.  Furthermore, we analyzed a key differentially methylated site between MRB and BL, and found that it was located in an intronic region of PcHY5.  The lower methylation levels in this PcHY5 intron in MRB were associated with red fruit color during development, whereas the higher methylation levels at the same site in BL were associated with green fruit color.  Based on the differential expression and methylation patterns in PcHY5 and gene functional verification, we hypothesize that PcHY5, which is regulated by methylation levels, affects anthocyanin biosynthesis and transport to cause the variations in skin color between BL and MRB.

Psathyrostachys huashanica Keng (2n=2x=14, NsNs) is regarded as a valuable wild relative species for common wheat cultivar improvement because of its abundant beneficial agronomic traits.  However, although the development of many wheat–P. huashanica-derived lines provides a germplasm base for the transfer of excellent traits, the lag in the identification of P. huashanica chromosomes in the wheat background has limited the study of these lines.  In this study, three novel nondenaturing fluorescence in situ hybridization (ND-FISH)-positive oligo probes were developed.  Among them, HS-TZ3 and HS-TZ4 could specifically hybridize with P. huashanica chromosomes, mainly in the telomere area, and HS-CHTZ5 could hybridize with the chromosomal centromere area.  We sequentially constructed a P. huashanica FISH karyotype and idiogram that helped identify the homologous groups of introduced P. huashanica chromosomes.  In detail, 1Ns and 2Ns had opposite signals on the short and long arms, 3Ns, 4Ns, and 7Ns had superposed two-color signals, 5Ns and 6Ns had fluorescent signals only on their short arms, and 7Ns had signals on the intercalary of the long arm.  In addition, we evaluated different ways to identify alien introgression lines by using low-density single nucleotide polymorphism (SNP) arrays and recommended the SNP homozygosity rate in each chromosome as a statistical pattern.  The 15K SNP array is widely applicable for addition, substitution, and translocation lines, and the 40K SNP array is the most accurate for recognizing transposed intervals between wheat and alien chromosomes.  Our research provided convenient methods to distinguish the homologous group of P. huashanica chromosomes in a common wheat background based on ND-FISH and SNP arrays, which is of great significance for efficiently identifying wheat–P. huashanica-derived lines and the further application of Ns chromosomes

Early defoliation, which usually occurs during summer in pear trees, is gradually becoming a major problem that poses a serious threat to the pear industry in southern China.  However, there is no system for evaluating the responses of different cultivars to early defoliation, and our knowledge of the potential molecular regulation of the genes underlying this phenomenon is still limited.  In this study, we conducted field investigations of 155 pear accessions to assess their resistance or susceptibility to early defoliation.  A total of 126 accessions were found to be susceptible to early defoliation, and only 29 accessions were resistant.  Among them, 19 resistant accessions belong to the sand pear species (Pyrus pyrifolia).  To identify the resistance genes related to early defoliation, the healthy and diseased samples of two sand pear accessions, namely, the resistant early defoliation accession ‘Whasan’ and the susceptible early defoliation accession ‘Cuiguan’, were used to perform RNA sequencing.  Compared with ‘Cuiguan’, a total of 444 genes were uniquely differentially expressed in ‘Whasan’.  Combined with GO and KEGG enrichment analyses, we found that early defoliation was closely related to the stress response.  Furthermore, a weighted gene co-expression network analysis revealed a high correlation of WRKY and ethylene responsive factor (ERF) transcription factors with early defoliation resistance.  This study provides useful resistant germplasm resources and new insights into potentially essential genes that respond to early defoliation in pears, which may facilitate a better understanding of the resistance mechanism and molecular breeding of resistant pear cultivars

Dwarfism is an important trait which is closely related to the efficiency of fruit orchard management and production.  However, dwarfing cannot be widely applied in the cultivation of pears, especially Asian pears.  Developing varieties with dwarf characteristics is a goal of paramount importance in pear breeding.  In the present study, dwarf phenotype pears (DPPs) and arborescent phenotype pears (APPs) were obtained from the offspring of a cross between ‘Aiyuxiang’ and ‘Cuiguan’ pear cultivars, which exhibited dwarfed and arborescent statures, respectively.  When compared with APPs, the heights of DPPs showed a 62.8% reduction, and the internode lengths were significantly shorter.  Cross-grafting between DPPs and APPs demonstrated that the dwarfed phenotype of DPPs was primarily induced by the aerial portions of the plant, and independent of the root system.  Observations of stem tissue sections showed that DPP cells were arranged chaotically with irregular shapes, and the average length was larger than that of the APP cells.  A total of 1 401 differently expressed genes (DEGs) in shoot apices between DPPs and APPs were identified by RNA-sequencing (RNA-Seq), and these DEGs were mainly enriched in the ‘phytohormone-related pathways, cell wall metabolism and cell division’ categories.  Moreover, 101 DEGs were identified as transcription factors (TFs).  In DPPs, several brassinosteroids (BR) signaling and cell cycle-related genes were significantly down-regulated, while genes involved in BR and GA degradation were up-regulated.  Comprehensive analysis of RNA-Seq data and stem tissue sections suggested that the dwarfed phenotype of DPPs could be primarily attributed to deficiencies in cell division.  Previous work using simple sequence repeat (SSR) markers narrowed the location of the gene responsible for the dwarf phenotype of ‘Le Nain Vert’.  Through combined analysis of our transcriptomic data with the SSR results, we identified four genes as promising candidates for the dwarf phenotype, among which, a DELLA gene could be the most promising.  The results presented in this study provide a sound foundation for further exploration into the genetic and molecular mechanisms underlying pear dwarfing.

Migratory insects make diverse adaptive strategies in response to changes in external environment.  Temperature has an impact on the survival, development, reproduction, and migration initiation of insects.  Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention.  Three constant temperature treatments (20, 25 and 30°C) and three pupal-alternating temperature treatments (20–25, 25–20 and 25–30°C) were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops.  The 25°C treatment was considered optimal with 20 and 30°C as low suitable temperature and high temperatures, respectively.  The survival rate was relatively low before third instar larvae at  20°C (63.0%) and 20–25°C (70.1%), and extreme low after pupal stage at 30°C (20.6%).  Developmental duration of each stage was negatively correlated with temperature.  The adult pre-oviposition period, when most migratory insects initiate migration, was the shortest at 25°C (2.69 d) but was lengthened at both low suitable (7.48 d for 20°C, 6.91 d for 25–20°C and 4.57 d for 20–25°C) and high temperatures (3.74 d for 25–30°C and 5.00 d for 30°C).  Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature.  The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.

Eating and cooking qualities (ECQs) of rice are important attributes due to its major influence on consumer acceptability. To better understand the molecular mechanism of the variation in ECQs, we investigated and compared the expressions among different alleles of the Waxy (Wx) gene and its effect on ECQs in specialty rice cultivars. The results showed that the accumulation of amylose was positively and significantly correlated to the level of mature Wx mRNA and granule-bound starch synthase I (GBSS I) in developing rice grain at 12 days after flowering. The amount of GBSS I and its activity together are the main factors controlling amylose synthesis. Differences in ECQs among five Wx allele types were investigated in samples from 15 rice varieties. The apparent amylose content (AAC) and gel consistency (GC) were similar in each type of Wx allele. The AAC followed the order, Wxa type>Wxin type>Wxb type>Wxmq type>wx. Contrary to this, the GC showed an opposite trend compared to AAC. There was a wide variation in rapid visco analyzer (RVA) profile among five Wx allele types, while varieties sharing a specified Wx allele had basically the similar RVA profile, although there was a slight difference in some RVA parameters, peak, hot paste and cool paste viscosities.

Insect pheromone-binding proteins (PBPs) play important roles in transporting hydrophobic pheromone components across the sensillum lymph to the surface of olfactory receptors (ORs). However, the PBPs of the oriental fruit moth, Grapholita molesta, an important destructive pest of stone fruits worldwide, are not well characterized. In this study, two new putative PBP genes, GmolPBP2 and GmolPBP3, were identified from G. molesta antennae. The deduced amino-acid sequences of these two putative PBP genes are characteristic of the odorant binding protein family, containing six conserved cysteine residues. The genomic DNA sequence of each gene contained two introns. However, the lengths and positions of the introns differed. RT-PCR analyses revealed that the two GmolPBP genes are only expressed in the antennae of female and male moths. Quantitative real-time PCR indicated that the transcription levels of GmolPBP2 are far greater than those of GmolPBP3 in both female and male antennae. GmolPBP3 showed higher transcription levels in female antennae than in male antennae, while GmolPBP2 showed similar transcription levels in both female and male antennae. The transcript levels of both genes were significantly different in premating and post-coitum individuals, implying that mating affects the process of sex pheromone reception. To better understand the functions, two GmolPBPs were expressed in Escherichia coli, and the ligand binding assays were conducted. Results showed that GmolPBP2 has strong binding affinities to two sex pheromone components, E8-12:Ac and Z8-12:Ac, as well as weaker binding affinities to Z8-12:OH and 12:OH. GmolPBP2 also bound some ordinary odor molecules. However, the affinity of GmolPBP3 to both sex pheromones and ordinary odor molecules was very weak. These results show that GmolPBP2 plays the main role in pheromone discrimination and recognition in the oriental fruit moth.