Fruit cracking occurs easily during the late period of fruit development when plants encounter an unsuitable environment, dramatically affecting fruit production and marketing.  This study conducted the bulked segregant RNA-Seq (BSR) to identify the key regulatory gene of fruit cracking in tomatoes.  BSR-Seq analysis illustrated that two regions associated with irregularly cracking were located on chromosomes 9 and 11, containing 127 candidate genes.  Further, through differentially expression analysis and qRT-PCR in cracking-susceptible and cracking-resistant genotypes, the candidate gene SlGH9-15 (Solyc09g010210) with significantly differential expression levels was screened.  Bioinformatics analysis of the GH9 gene family revealed that 20 SlGH9 genes were divided into three groups.  The phylogenetic analysis showed that SlGH9-15 was closely related to cell wall construction-associated genes AtGH9B1, AtGH9B6, OsGH9B1, and OsGH9B3.  The cis-acting elements analysis revealed that SlGH9-15 was activated by various hormones (ethylene and ABA) and abiotic stresses.  The expression pattern indicated that 13 SlGH9 genes, especially SlGH9-15, were highly expressed in the cracking-susceptible genotype.  Its expression level gradually increased during fruit development and achieved maximum value at the red ripe stage.  Additionally, the cracking-susceptible tomato showed higher cellulase activity and lower cellulose content than the cracking-resistant tomato, particularly at the red ripe stage.  This study identified SlGH9-15 as a key gene associated with fruit cracking in tomatoes for the first time and gives new insights for understanding the molecular mechanism and complex regulatory network of fruit cracking

High-yield rice varieties with a suitable growth duration are required for mechanical transplanting in multiple cropping systems.  Daily yield is an appropriate criterion for the selection of machine-transplanted rice varieties.  The aim of this study was to investigate the growth characteristics and grain production in machine-transplanted medium indica hybrid rice with a high daily yield.  We conducted a field experiment on 20 medium indica hybrid rice varieties in 2017 and 2018.  Grain yield decreased significantly with growth duration between jointing and heading, but it increased with dry matter accumulation, growth rate between jointing and heading, dry matter partitioning to the stem plus sheath at heading, daily yield, and number of spikelets per panicle.  Compared with the medium and low daily yield variety types, the high daily yield variety type increased shoot biomass by improving crop growth rate and dry matter accumulation amount between jointing and heading and after heading.  The high daily yield variety type decreased the growth duration pre-heading and the proportions of dry matter partitioned to the leaf lamina at heading and maturity, but it also increased the post-heading accumulated dry matter in the grain and the remobilization of dry matter stored in the vegetative organs.  Furthermore, the high daily yield variety type significantly increased the occurrence rate of tillers, which is beneficial for the formation of a larger panicle size and an increase in the grain-filling rate.  These changes contributed to a 6.51–23.16% relative increase in grain yield of the high daily yield variety type.  In conclusion, the selection of high daily yield indica hybrid rice varieties with shorter pre-heading growth duration, greater tiller occurrence rate and spikelet numbers per panicle, higher post-jointing growth rates and stem plus sheath dry matter accumulation at heading is suitable for machine-transplanted rice.

Rational application of different forms of nitrogen (N) fertilizer for peanut (Arachis hypogaea L.) requires tracking the N supplied sources which are commonly not available in the differences among the three sources: root nodule, soil and fertilizer. In this study, two kinds of peanut plants (nodulated variety (Huayu 22) and non-nodulated variety (NN-1)) were choosed and four kinds of N fertilizers: urea-N (CONH2-N), ammonium-N (NH4 +-N), nitrate-N (NO3 –-N) and NH4 ++NO3 –-N labeled by 15N isotope were applied in the field barrel experiment in Chengyang Experimental Station, Shandong Province, China, to determine the N supplied sources and N use efficiency over peanut growing stages. The results showed that intensities and amounts of N supply from the three sources were all higher at middle growing stages (pegging phase and podding phase). The accumulated amounts of N supply from root nodule, soil and fertilizer over the growing stages were 8.3, 5.3 and 3.8 g m–2 in CONH2-N treatment, which are all significantly higher than in the other three treatments. At seedling phase, soil supplied the most N for peanut growth, then root nodule controlled the N supply at pegging phase and podding phase, but soil mainly provided N again at the last stage (pod filling phase). For the whole growing stages, root nodule supplied the most N (47.8 and 43.0%) in CONH2-N and NH4 +-N treatments, whereas soil supplied the most N (41.7 and 40.9%) in NH4 ++ NO3 –-N and NO3 –-N treatments. The N use efficiency was higher at pegging phase and podding phase, while accumulated N use efficiency over the growing stages was higher in CONH2-N treatment (42.2%) than in other three treatments (30.4% in NH4 +-N treatment, 29.4% in NO3 –-N treatment, 29.4% in NH4 ++NO3 –-N treatment). In peanut growing field, application of CONH2-N is a better way to increase the supply of N from root nodule and improve the N use efficiency.

    The objectives of this study were to estimate the genetic parameters and the breeding progress in a Landrace herd in China, and to predict the potential benefits by applying new breeding technology. Hereby, the performance records from a Landrace swine herd in China, composing over 33 000 pigs born between 2001 and 2013, were collected on six economically important traits, i.e., average daily gain between 30–100 kg (ADG), adjusted backfat thickness at 100 kg (BF), adjusted days to 30 kg (D30), adjusted days to 100 kg (D100), number born alive (NBA), and total number born (TNB). The genetic parameters were estimated by restricted maximum likelihood via DMU, and realized genetic trends were analyzed. Based on the real population structure and genetic parameters obtained from this herd, the potential genetic trends by applying genomic selection (GS) were predicted via a computer simulation study. Results showed that the heritability estimates in this Landrace herd were 0.55 (0.02), 0.42 (0.01), and 0.12 (0.01), for BF, D100, and TNB, respectively. Favorable genetic trends were obtained for D100, BF, and TNB due to direct selection, for ADG and NBA due to indirect selection. Long-term selection against D100 did not improve D30, though they are highly genetically correlated (0.64). Appling GS in such a swine herd, the genetic gain can be increased by 25%, or even larger for traits with low heritability or individuals without phenotypes before selection. It can be concluded that conventional breeding strategy was effective in the herd studied, while applying GS is promising and hence the road ahead in swine breeding.

Somatic nuclear transfer technology has become increasingly promising in biomedicine and agriculture. Whereas the approach remains inefficient and underlying mechanisms remain ambiguous. Although cloned embryos have similar in vitro developmental capacity as in vitro fertilized (IVF) embryos before implantation, they appeared to have much lower full-term developmental efficiency in pig and cattle, and thus it would be reasonable to postulate that profound distinction at the molecular level should exist between them. Herein, RNA sequencing technique was used to screen differentially expressed genes in cloned and IVF blastocysts, and in total 628 differentially expressed transcripts were obtained, among which, 280 transcripts are up-regulated and 348 transcripts are down-regulated in cloned blastocysts. Moreover, one statistically significant pathway associated with endoplasmic reticulum (ER) protein processing was enriched, and some ER-stress markers such as ATF4, ATF6, PDIA3, HSPA1B, HSP40 and HSP90 between cloned and IVF blastocysts were suggested. Additionally, some developmentally important genes such as lipid metabolism related genes (MGLL, DDHD2 and FADS2) and epigenetic modification genes (DNMT1, KDM5C and MBD3L5) were found differentially expressed between cloned and IVF embryos.

Many animal feed grains contain high β-glucan in the cell wall. Pigs do not secret β-glucanase to degrade the β-glucan in their feed. The indigestible β-glucan not only blocks the release of nutrients from the grain cell wall, but also increases the digesta viscosity in the gastrointestinal tract of pigs. Therefore, dietary β-glucan significantly inhibits nutrient digestion and absorption in pigs. Transgenic expression of β-glucanase in the digestive tract of pigs may offer a solution to solve this problem. In the current study, four arti?cial codon-optimized β-glucanases genes was prepared and expressed in porcine cells. Only pBgA and pEgx showed high activity in transfected pig kidney cells. To improve the pH range and pH stability of β-glucanase, the two β-glucanases, pBgA and pEgx, were co-expressed in pig kidney cells and salivary gland cells by Linker A3 or 2A peptide. The resulting dual enzymes of pBgA3pEg and pBg2ApEg showed significantly enlarged pH range and significantly increased pH stability, as compared to parental enzymes. These results provide useful data for future study on increasing the feed digestibility of pigs by transgenic expression of β-glucanase in their salivary glands.

Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efficiency in agriculture. This study investigated the effects of starting-N plus topdressing N applications (as compared to the common practice of all basal application) on soybean photosynthetic capacity under different planting densities. A field experiment was conducted in two growing seasons (2011 and 2012), and the soybean (Glycine max L. Merrill) cultivar was Dongnong 52, three planting densities (20, 25 and 30 plants m-2), and four N fertilizer application patterns (all N fertilizer of 6 g N m-2 as basal fertilizer, all N fertilizer as topdressing at beginning pod stage (R3), 1.8 g N m-2 as basal fertilizer and 4.2 g N m-2 as topdressing at stage R3 and full pod stage (R4), respectively). The results indicated that under the same planting density, compared to applying all N as basal fertilizer, the application of starter-N plus topdressing N substantially reduced the rate of pod abscission, and enhanced leaf area index (LAI) significantly at beginning seed stage (R5) (P<0.05), net assimilation rate (NAR) during stages R4-full seed stage (R6) (P<0.05), contribution rate of post-seed filling assimilate to seed (CPA) (P<0.05), and yield (P<0.05). Applying topdressing N at stage R4 resulted in higher net primary production and yield than applying topdressing N at stage R3. When applying starter-N plus topdressing N at planting density of 25 plants m-2, LAI after stage R5 and NAR after stage R4 were increased by 5.92-16.3% (P<0.05) and 13.7-26.6% (P<0.05) with the planting density of 20 plants m-2, respectively, and yield was 8.46-14.0% (P<0.05) higher than that under 20 plants m-2. When planting density increased to 30 plants m-2, only LAI during stages R4-R5 and NAR during stages R4-R5 increased by applying starter-N plus topdressing N, while the other indexes declined. Overall, results of this study demonstrated that applying starter-N plus topdressing N could significantly enhance soybean photosynthetic capacity after stage R5 at planting density of 25 plants m-2.

To determine the genetic diversity and population structure of sweet potato accessions cultivated in China, and to establish the genetic relationships among their germplasm types, a representative collection of 240 accessions was analyzed using inter-simple sequence repeat (ISSR) markers. The mean genetic similarity coefficient, Nei’s gene diversity, and shared allele distance of tested sweet potato accessions were 0.7302, 0.3167 and 0.2698, respectively. The 240 accessions could be divided into six subgroups and five subpopulations based on neighbor-joining (NJ) clustering and STRUCTURE results, and obvious genetic relationships among the tested sweet potato accessions were identified. The marker-based NJ clustering and population structure showed no distinct assignment pattern corresponding to flesh color or geographical ecotype of the tested sweet potato germplasm. Analysis of molecular variance (AMOVA) revealed small but significant difference between white and orange-fleshed sweet potato accessions. Small but significant difference were also observed among sweet potato accessions from the Southern summer-autumn sweet potato region, the Yellow River Basin spring and summer sweet potato region and the Yangtze River Basin summer sweet potato region. This study demonstrates that genetic diversity in the tested sweet potato germplasm collection in China is lower than that in some reported sweet potato germplasm collections from other regions. Pedigree investigations suggest that more diverse Chinese sweet potato varieties should be formed by broadening the selection scope of breeding parents and incorporating the introduced varieties into future breeding programs.

Heat and acid treatments were reported to be a promising substitute for SO2 fumigation in color protection of postharvest lychee (Litchi chinensis Sonn.) fruits, but the mechanism was not clear. In the present study, hot water (70°C) dipping followed by immersion in 2% HCl (heat-acid) substantially protected the red color of the fruit during storage at 25°C and inhibited anthocyanin degradation while hot water dipping alone (heat) led to rapidly browning and about 90% loss in anthocyanin content. The pH values in the pericarp of the heat-acid treated fruit dropped to 3.2, while the values maintained around 5.0 in the heat-treated and control fruit. No significantly different pH values were detected among the arils of heat-acid, heat treated and control fruit. Heat-acid treatment dramatically reduced the activities of anthocyanin degradation enzyme (ADE), peroxidase (POD) and polyphenol oxidase in the pericarp. A marked reduction in LcPOD gene expression was also detected in heat-acid treated fruit, in contrast, induction was found in heat treated fruit. The pericarp of heat-acid treated fruit exhibited significantly lower respiration rate but faster water loss than that of the untreated or heat treated fruit. Taken together, heat treatment triggered quick browning and anthocyanin loss in lychee fruit, while heat-acid treatment protected the fruit color by a great reduction in the activities/gene expression of anthocyanin degradation enzymes and acidification of lychee pericarp.