A SCAR marker linked to the N gene for resistance to root knot nematodes (Meloidogyne spp.) in pepper (Capsicum annuum L.)

The root-knot nematodes (Meloidogyne spp.) are important nematode pests and cause serious diseases in pepper in the world. No molecular markers linked to the nematodes resistance N gene have been reported. In this paper, ‘Carolina Wonder’ (Capsicum annuum L.), a sweet pepper line resistant to root-knot nematode with N gene, ‘20080-5-29’ (C. annuum L.), an inbred line susceptible to root-knot nematode with good horticultural characteristics, and their F₂ progeny with 320 individuals were used as materials. Evaluation of resistance and susceptibility of parental lines, F₁ and F₂ progeny inoculated with root-knot nematodes (Meloidogyne incognita) were carried out. ‘Bulked segregant analysis’ method was used to search for polymorphic markers from 512 pairs of AFLP primers. Based on the assessment of resistance and susceptibility and polymorphism of the AFLP marker in F₂ population, the genetic linkage distance between the AFLP marker and the N gene was estimated. One AFLP marker E39/M41-339 was obtained and transferred to a SCAR marker amplifying a 315 bp DNA fragment linked to the N resistant allele and a 331 bp fragment linked to the N⁺ susceptible allele. The distance between the molecular marker and the nematodes resistance N gene is 6.3 cM. This research delivered a valuable tool for the marker assisted selection of nematodes resistance in pepper.     

Immune responses and enhanced disease resistance in Chinese drum, Miichthys miiuy (Basilewsky), after oral administration of live or dead cells of Clostridium butyrium CB2

Clostridium butyrium CB2 isolated from chickens was tested as a potential fish probiotic in the Chinese drum, Miichthys miiuy . Fish were fed live (CB), dead CB2 (D-CB) cells (10⁸ cells g⁻¹) or spent culture supernatant (SCS), for 30 days and challenged with Vibrio anguillarum or Aeromonas hydrophila . Survival was higher in both the CB and the CB-D fed groups, but the SCS group was not significantly different from the control. After feeding live or dead CB2 cells, there was increase in phagocytic activity of the head kidney macrophages, the lysozyme activity of serum and gut mucosa and immunoglobulin (Ig) level. The SCS group showed no obvious change in immune parameters. The results suggest that live or dead Clostridium butyrium CB2 has an immunomodulatory effect on fish.     

梨新品种--华酥

‘华酥’为‘早酥’ב八云’种间杂交育成的早熟优质高产抗病梨新品种。果实成熟比早酥早 10～ 15d。果实圆形 ,单果质量 2 0 0～ 2 50g ,果皮黄绿色 ,果肉质细 ,酥脆多汁 ,酸甜适口 ,风味浓并具芳香 ,品质佳。早果高产 ,7年生树产量为 4 2 .5t/hm2 。高抗黑星病。     

Combining multi-source data to explore a mechanism for the effects of micrometeorological elements on nutrient variations in paddy land water

Paddy land plays a key role in global crop production. Thus, paddy land water is a potential source of nitrogen and phosphorus; both nutrients largely contribute to non-point source pollution because they usually vary closely with micrometeorological elements (MEs) during the growth period. However, few studies have focused on the mechanism of co-variation between nutrients and MEs at the field scale. The relationships between nutrients in the paddy land water and MEs as well as soil water content, soil temperature, and the normalized difference vegetation index (NDVI) are still unclear. In this paper, an in situ experiment was designed to obtain 5 years of meteorological data and nutrient data (nitrogen and phosphorus); the size of the experiment plot is in accordance with the spatial resolution of NDVI data. Multi-source meteorological and satellite data were integrated to explore the mechanism of co-variation. The results show that precipitation, air temperature, and solar radiation are the three MEs significantly affecting the nitrogen concentration in the paddy land water during the growth period. The air temperature is the most important ME influencing the phosphorus concentration. At the same time, the NDVI, as an effective indicator of the photosynthetic potential of rice used to explore the relationship between nutrients, has a prominent influence on soluble nutrients, especially on dissolved phosphorus. These findings could significantly improve our understanding about the responses of paddy land nutrients during the growth period to the surrounding drivers, inclusive of MEs, soil water, soil temperature, and NDVI. Undoubtedly, it is a potentially helpful means to monitor the sources of non-point pollution.     

Potassium fertilization improves apple fruit (Malus domestica Borkh. Cv. Fuji) development by regulating trehalose metabolism

Potassium (K) fertilization and antioxidant enzymes both positively influence plant growth and development. However, it is not known whether K treatment improves fruit development via increasing soluble sugar. In this study, K-treated apple (Malus domestica Borkh.) fruit was harvested from 60 to 150 days after full bloom and was analyzed for ROS production and trehalose metabolism. The results show that K fertilization improved fruit firmness, increased growth according to several parameters, increased soluble sugar content, and decreased ROS production. The ascorbate metabolic pathway more effectively reduced ROS production than catalase and peroxidase (POD) did under K treatment. Trehalose-treated fruit also showed higher activity of ascorbate-related enzymes (DHAR, GR, and APX) compared with non-treated fruit. The changes of antioxidant enzyme activity in trehalose-treated fruit corresponded to those in K-treated fruit. Moreover, trehalase (TREH) activity in fruit was notably reduced by K treatment. This demonstrates that K influences ROS production via regulating trehalose content and TREH activity in fruit. This study provides new insight into the K mechanism which improves fruit development, including fruit firmness and size.     

Effects of formic acid and potassium diformate on the fermentation quality,chemical composition and aerobic stability of alfalfa silage

The objective of this study was to evaluate the efficacy of potassium diformate (KDF) as a potential additive for alfalfa silage. Fresh alfalfa was untreated or treated with formic acid (4 g/kg fresh weight, FW) or three concentrations of KDF (4, 5.5 or 7 g/kg FW). After 60 days of ensiling, the addition of formic acid and greater levels of KDF (5.5 and 7 g/kg) effectively reduced silage pH and inhibited the undesirable bacteria, indicated by lower butyric acid, ethanol, ammonia N concentrations and microbial populations (including enterobacteria, yeasts, moulds and clostridia). Additives decreased the dry‐matter loss, and more water‐soluble carbohydrates were preserved in the silages with formic acid or potassium diformate than in the control. Alfalfa silages treated with formic acid at 4 g/kg FW or potassium diformate at 5.5 or 7 g/kg FW were classified as the highest quality silage based on the higher Flieg's point (above 70) and remained stable for more than 9 days during aerobic exposure. Potassium diformate is recommended as an effective additive for alfalfa silages at a level of 5.5 or 7 g/kg FW under the humid and hot conditions of southern China.     

Exogenous application of melatonin improves plant resistance to virus infection

In this study, melatonin (MEL)-mediated plant resistance to tobacco mosaic virus (TMV) was examined to study local infection in Nicotiana glutinosa and systemic infection in Solanum lycopersicum. Exogenous application of 100 µm MEL increased anti-virus infection activity to 37.4% in virus-infected N. glutinosa plants. The same treatment significantly reduced relative levels of virus RNA analysed by qRT-PCR and virus titres measured by dot-ELISA, and increased the relative expression levels of the PR1 and PR5 genes analysed by qRT-PCR, in virus-infected S. lycopersicum. MEL treatment induced considerable accumulations of salicylic acid (SA) and nitric oxide (NO) but did not significantly affect production of hydrogen peroxide (H₂O₂) in the virus-infected S. lycopersicum plants. Transgenic nahG N. tabacum was used to determine whether MEL-induced TMV resistance was dependent on the SA pathway. The results showed that the relative RNA level of the TMV analysed by qRT-PCR and virus titres analysed by dot-ELISA were not reduced by the MEL treatment in the nahG transgenic N. tabacum seedlings treated twice with 100 µm MEL. The increased relative expression levels of PR1 and PR5 were greatly reduced when cPTIO, an NO scavenger, was included in the MEL treatment. A working model of MEL-mediated plant resistance to TMV is proposed. MEL-mediated plant resistance to viruses provides a new avenue to control plant viral diseases.