Sugar content is a determinant of apple (Malus×domestica Borkh.) sweetness.  However, the molecular mechanism underlying sucrose accumulation in apple fruit remains elusive.  Herein, this study reported the role of the sucrose transporter MdSUT2.1 in the regulation of sucrose accumulation in apples.  The MdSUT2.1 gene encoded a protein with 612 amino acid residues that could be localized at the plasma membrane when expressed in tobacco leaf protoplasts.  MdSUT2.1 was highly expressed in fruit and was positively correlated with sucrose accumulation during apple fruit development.  Moreover, complementary growth assays in a yeast mutant validated the sucrose transport activity of MdSUT2.1.  MdSUT2.1 overexpression in apples and tomatoes resulted in significant increases in sucrose, fructose, and glucose contents compared to the wild type (WT).  Further analysis revealed that the expression levels of sugar metabolism- and transport-related genes SUSYs, NINVs, FRKs, HXKs, and TSTs increased in apples and tomatoes with MdSUT2.1 overexpression compared to WT.  Finally, unlike the tonoplast sugar transporters MdTST1 and MdTST2, the promoter of MdSUT2.1 was not induced by exogenous sugars.  These findings provide valuable insights into the molecular mechanism underlying sugar accumulation in apples.

With the development of sequencing technology, insertions-deletions (InDels) have been increasingly reported to be involved in the genetic deter mination of agronomical traits.  However, most studies have focused on the identification and application of short-InDels (1–15 bp) for genetic analysis.  The objective of this study was to deeply deploy long-InDels (>15 bp) for the genetic analysis of important agronomic traits in soybean.  A total of 13 573 polymorphic long-InDels were identified between parents Zhongpin 03-5373 (ZP) and Zhonghuang 13 (ZH), which were unevenly distributed on 20 chromosomes of soybean, varying from 321 in Chr11 to 1 246 in Chr18.  Consistent with the distribution pattern of annotated genes, the average density of long-InDels in arm regions was significantly higher than that in pericentromeric regions at the P=0.01 level.  A total of 2 704 (19.9% of total) long-InDels were located in genic regions, including 319 large-effect long-InDels, which resulted in truncated or elongated protein sequences.  A previously identified QTL (qPH16) underlying plant height was further analyzed, and it was found that 26 out of 35 (74.3%) long-InDel markers located in the qPH16 region showed clear polymorphisms between parents ZP and ZH.  Seven markers, including three long-InDels and four previously reported SNP markers, were used to genotype 242 recombinant inbred lines derived from ZP×ZH.  As a result, the qPH16 locus was narrowed from a 960-kb region to a 477.55-kb region, containing 65 annotated genes.  Therefore, these long-InDels are a complementary genetic resource of SNPs and short-InDels for plant height and can facilitate genetic studies and molecular assisted selection breeding in soybean.

Plant height is an important agronomic trait, which is governed by multiple genes with major or minor effects.  Of numerous QTLs for plant height reported in soybean, most are in large genomic regions, which results in a still unknown molecular mechanism for plant height.  Increasing the density of molecular markers in genetic maps will significantly improve the efficiency and accuracy of QTL mapping.  This study constructed a high-density genetic map using 4 011 recombination bin markers developed from whole genome re-sequencing of 241 recombinant inbred lines (RILs) and their bi-parents, Zhonghuang 13 (ZH) and Zhongpin 03-5373 (ZP).  The total genetic distance of this bin map was 3 139.15 cM, with an average interval of 0.78 cM between adjacent bin markers.  Comparative genomic analysis indicated that this genetic map showed a high collinearity with the soybean reference genome.  Based on this bin map, nine QTLs for plant height were detected across six environments, including three novel loci (qPH-b_11, qPH-b_17 and qPH-b_18).  Of them, two environmentally stable QTLs qPH-b_13 and qPH-b_19-1 played a major role in plant height, which explained 10.56–32.7% of the phenotypic variance.  They were fine-mapped to 440.12 and 237.06 kb region, covering 54 and 28 annotated genes, respectively.  Via the function of homologous genes in Arabidopsis and expression analysis, two genes of them were preferentially predicted as candidate genes for further study.

High-molecular-weight glutenin subunits (HMW-GSs) play a critical role in determining the viscoelastic properties of wheat dough.  The HMW-GSs are encoded by Glu-A1, Glu-B1, and Glu-D1 loci on the long arms of chromosomes 1A, 1B, and 1D, respectively.  In the present study, four near-isogenic lines with different HMW-GS deletions and compositions at the Glu-A1 and Glu-D1 loci in Yangmai 18 background were used for quality analysis.  Deletion in Glu-D1 showed much weaker gluten quality and dough strength than null Glu-A1 genotype and wild genotype (WT), based on the measurements of sodium dodecyl sulfate (SDS)-sedimentation, lactic acid solvent retention capacity (SRC), gluten index, development time, stability time, and alveograph P and L values.  The deletion of Glu-D1 did not significantly affect grain hardness, grain protein content, water SRC, sodium carbonate SRC, and sucrose SRC.  Double null genotype in Glu-A1 and Glu-D1 and single null genotype in Glu-D1 showed significantly higher cookie diameter, crispness, and lower cookie height compared with single null genotype in Glu-A1 and WT.  These indicate that the null Glu-D1 genotype is useful for improvement of biscuit quality, and use of this germplasm would be a viable strategy to develop new wheat varieties for biscuit processing.

    The enzyme Δ³,Δ²-dienoyl-CoA isomerase (ECI1) plays a crucial role in the mitochondrial β-oxidation of fatty acids with a double-bond in odd and even positions. The ECI1 gene might be a qualified candidate for studies pertaining to lipid deposition and meat quality in swine. In the present study, ECI1 cDNA of the Tibetan pig was obtained by in silico cloning and verified by PCR analysis. Single-nucleotide polymorphisms (SNPs) of ECI1 were screened by PCR-sequencing and genotypes of those SNPs were tested by PCR-restriction fragment length polymorphism (PCR-RFLP) in Diannan small-ear pigs (DSP, n=40), Tibetan pigs (TP, n=60) and Yorkshire pigs (YP, n=30). The expression levels of ECI1 were analyzed by real-time quantitative PCR and Western blotting in tissues of the liver, backfat, and longissimus dorsi (LD) muscle of DSP (n=8), TP (n=8) and YP (n=8). Single factor linear correlation analysis was applied separately for each breed to evaluate correlations between ECI1 gene expression in the LD muscle and intramuscular fat (IMF) content. We obtained an ECI1 gene length of 1 401 bp from the cDNA that contained a full coding region of 909 bp. Three novel SNPs (g.42425337G>A; g.42424666A>G; and g.42422755A>G) were detected, and only g.42424666A>G exhibited three genotypes among the three breeds. The ECI1 expression levels in the LD muscle of DSP and TP were significantly higher than that of YP (P<0.05). Moreover, TP had the highest ECI1 expression in backfat (P<0.01), and a positive correlation was observed between gene expression and IMF content. The results suggest that differences in ECI1 gene expression might be related to lipid deposition and meat quality in pig.

   Metarhizium anisopliae as an essential entomopathogenic fungus has been known to produce destruxins (a kind of cyclo-peptidic mycotoxins) and blastospores in submerged culture. Blastospores and destruxins are candidates for insecticides, but the relations of both productions and the impact factors are unclear yet. In this study, we investigated the effects of inoculums, rotation, dissolved oxygen (DO) on the productions of blastospores and destruxins A and B (DA and DB) in submerged culture of M. anisopliae strain MaQ01. The results indicated that DO levels were regulated by inoculum amounts and rotation speeds, meanwhile, the productions of DA, DB and blastospores were also closely influenced by those factors. Totally, when DO value was more than 40%, the higher productions of destruxins and blastospores were achieved, by contrast, lower than 40% of DO values resulted in lower productions. The regression analysis suggested that the productions of DA, DB and blastospores were positively correlated with the DO levels. Meanwhile, the positive correlations between the productions of DA or DB and blastospores were also found. Briefly, when the rotation is 150 r min–1 and the inoculum is 1.0×10⁶ spore mL^–1, the DA, DB and blastospores achieved the best production of 61.81 mg mL^–1, 24.74 mg mL^–1 and 5.73×10⁶ spore mL^–1, respectively. In addition, the pathogenicities of blastospores and conidia against Plutella xylostella were bioassayed. The higher mortalities of P. xylostella were totally recorded in blastospore treatments than in conidia treatments, especially in lower dosages and earlier periods. Our research will give some new insights to production of destruxins and blastospores by using M. anisopliae.