NtSWEET1 promotes tobacco resistance to Fusarium oxysporum-induced root rot disease.

Sugars Will Eventually be Exported Transporter (SWEET) is a newly characterized family of sugar transporters, which plays critical roles in plant-pathogen interactions. However, the function of SWEET in tobacco and its interaction with Fusarium oxysporum, a causal agent of root rot, remain unclear. This study aimed to dissect the function of NtSWEETs in tobacco root rot using stem bases from tobacco plants inoculated with F. oxysporum. RNA-sequencing (RNA-Seq) analysis was performed, and the results indicated that Sucrose Transporter 4 (NtSUC4), Sugar Transporter 12 (NtSTP12), Hexose Transporter 6 (NtHEX6), NtSWEET1, NtSWEET3b, and NtSWEET12 were downregulated by infection with F. oxysporum. The expression of NtSWEET1, but not of NtSUC4, NtSTP12, NtHEX6, NtSWEET3b, or NtSWEET12, was suppressed at all the time points tested after inoculation with F. oxysporum. The NtSWEET1-green fluorescent protein was localized on the plasma membrane and possessed the ability to transport glucose, fructose and galactose. Compared with the wild-type plants, NtSWEET1 RNAi plants were more susceptible to root rot, indicating that NtSWEET1 positively regulated the defense of tobacco against root rot. This study identified the role of SWEETs in tobacco and their interaction with F. oxysporum. The results might be useful in protecting tobacco plants from root rot.

Transcriptome sequencing and differential gene expression analysis of the schistosome-transmitting snail Oncomelania hupensis inhabiting hilly and marshland regions.

The freshwater snail Oncomelania hupensis is the unique intermediate host of the blood fluke Schistosoma japonicum, which is the major cause of schistosomiasis. The snail inhabits two contrasting environments: the hilly and marshland regions. The hilly snails are smaller in size and have the typical smooth shell, whereas the marshland snails are larger and possess the ribbed shell. To reveal the differences in gene expression between the hilly and marshland snails, a total of six snails, three per environment, were individually examined by RNA sequencing technology. All paired-end reads were assembled into contigs from which 34,760 unigenes were predicted. Based on single nucleotide polymorphisms, principal component analysis and neighbor-joining clustering revealed two distinct clusters of hilly and marshland snails. Analysis of expression changes between environments showed that upregulated genes relating to immunity and development were enriched in hilly snails, while those associated with reproduction were over-represented in marshland snails. Eight differentially expressed genes between the two types of snails were validated by qRT-PCR. Our study identified candidate genes that could be targets for future functional studies, and provided a link between expression profiling and ecological adaptation of the snail that may have implications for schistosomiasis control.

[Progress of researches on lysozyme and its expression in Oncomelania hupensis].

Lysozyme generally exists in animals, plants and microorganisms, and it is used as a natural anti-infection material and one of the important non-specific immune factors in organisms. This paper reviews the progress of researches on its classification, gene structure and function, and expression regulation in Oncomelania hupensis, and on the factors affecting its activities in recent years, in order to further discuss its distribution in O. hupensis.

[Relationship between Yangtze River floodplain micro ecological environment and distribution of Oncomelania hupensis snails].

OBJECTIVE: To explore the relationship between the Yangtze River floodplain ecological environment (vegetation, soil, water and light intensity) and the distribution of Oncomelania hupensis snails, so as to provide the evidence for ecological snail control. METHODS: Three regions (the Lu-Gang Bridge, Dragon Nest Lake in the bund, and Dragon Nest lake beach) were selected to investigate the plant characteristics (species, height, coverage, frequency and strain of clusters), soil characteristics (temperature, humidity, light intensity) and pH value. All the results were analyzed statistically with SPSS 18 software. RESULTS: A total of 920 boxes were investigated. The vegetation coverage was 3.7%-63.5%, and the dominant population was Cyperusrotundus L. cluster on the marshland. The soil temperature was 19.0 degrees C-24.0 degrees C, pH 5.0-5.7, and humidity 53%-75%. There were statistical significants in average number of living snails and dead snails among 3 groups (P < 0.05). As the light intensity was strong in summer and weak in winter, the snails were in the back surface in summer and front surface in winter respectively. The average number of living snails was the most near the water. The difference was statistical significant (P < 0.01) among three ranges (0-1 m, 1-3 m and 3-5 m). CONCLUSION: The snail survival and distribution have close relations with micro ecological environment factors, such as vegetation, soil, water and light intensity.