Effects of an EPSPS-transgenic soybean line ZUTS31 on root-associated bacterial communities during field growth.

The increased worldwide commercial cultivation of transgenic crops during the past 20 years is accompanied with potential effects on the soil microbial communities, because many rhizosphere and endosphere bacteria play important roles in promoting plant health and growth. Previous studies reported that transgenic plants exert differential effects on soil microbial communities, especially rhizobacteria. Thus, this study compared the soybean root-associated bacterial communities between a 5-enolpyruvylshikimate-3-phosphate synthase -transgenic soybean line (ZUTS31 or simply Z31) and its recipient cultivar (Huachun3 or simply HC3) at the vegetative, flowering, and seed-filling stages. High-throughput sequencing of 16S rRNA gene (16S rDNA) V4 hypervariable region amplicons via Illumina MiSeq and real-time quantitative PCR (qPCR) were performed. Our results revealed no significant differences in the overall alpha diversity of root-associated bacterial communities at the three developmental stages and in the beta diversity of root-associated bacterial communities at the flowering stage between Z31 and HC3 under field growth. However, significant differences in the beta diversity of rhizosphere bacterial communities were found at the vegetative and seed-filling stages between the two groups. Furthermore, the results of next generation sequencing and qPCR showed that the relative abundances of root-associated main nitrogen-fixing bacterial genera, especially Bradyrhizobium in the roots, evidently changed from the flowering stage to the seed-filling stage. In conclusion, Z31 exerts transitory effects on the taxonomic diversity of rhizosphere bacterial communities at the vegetative and seed-filling stages compared to the control under field conditions. In addition, soybean developmental change evidently influences the main symbiotic nitrogen-fixing bacterial genera in the roots from the flowering stage to the seed-filling stage.

Genome-wide Association Mapping of Quantitative Trait Loci (QTLs) for Contents of Eight Elements in Brown Rice (Oryza sativa L.).

An association mapping of quantitative trait loci (QTLs) regulating the concentrations of eight elements in brown rice (Oryza sativa L.) was performed using USDA mini-core subset cultivated in two different environments. In addition, correlation between the grain elemental concentrations was also studied. A total of 60 marker loci associated with 8 grain elemental concentrations were identified, and these loci were clustered into 37 genomic regions. Twenty new QTLs were found to be associated with important elements such as Zn, Fe, and P, along with others. Fe concentration was associated with the greatest number of markers in two environments. In addition, several important elemental/metal transporter genes were identified in a few mapped regions. Positive correlation was observed within all grain elemental concentrations. In summary, the results provide insight into the genetic basis of rice grain element accumulation and may help in the identification of genes associated with the accumulation of Zn, Fe, and other essential elements in rice.

Screening Chinese soybean genotypes for Agrobacterium-mediated genetic transformation suitability.

The Agrobacterium-mediated transformation system is the most commonly used method in soybean transformation. Screening of soybean genotypes favorable for Agrobacterium-infection and tissue regeneration is the most important step to establish an efficient genetic transformation system. In this study, twenty soybean genotypes that originated from different soybean production regions in China were screened for transient infection, regeneration capacity, and stable transgenic efficiency. Three genotypes, Yuechun 04-5, Yuechun 03-3, and Tianlong 1, showed comparable stable transgenic efficiencies with that of the previously reported American genotypes Williams 82 and Jack in our experimental system. For the Tianlong 1, the average stable transformation efficiency is 4.59%, higher than that of control genotypes (Jack and Williams 82), which is enough for further genomic research and genetic engineering. While polymerase chain reaction (PCR), LibertyLink strips, and ß-glucuronidase (GUS) staining assays were used to detect the insertion and expression of the transgene, leaves painted with 135 mg/L Basta could efficiently identify the transformants.

[Research progress in ARF-GEF gene family].

ARF-GEFs are a family of guanine-nucleotide exchange factors catalyzing the exchange of GDP for GTP on ADP-ribosylation factor. Large ARF-GEFs are highly conserved in all eukaryotes. It is an important regulator in both membrane dynamics and protein trafficking. Significant progress has been made in elucidating the structure, subcellular localization, and physiological functions of ARF-GEFs as a hot topic of cell biology recently. In this review, the character-istics and distribution of ARF-GEFs in different species, and recent research progress of ARF-GEFs and their regulation system are summarized.

Expression of the Arabidopsis thaliana histone gene AtHTA1 enhances rice transformation efficiency.

We expressed the Arabidopsis thaliana histone AtHTA1 in rice under the control of the maize ubiquitin promoter. Transformation efficiencies of rice plants that constitutively expressed AtHTA1 were 28-44% higher than calli containing an empty vector control. Furthermore, co-infection of rice calli with a vector containing AtHTA1 and another vector with the target gene increased transformation by 27-50%. Thus, expression of AtHTA1 either transiently or in stably transformed cells improved rice transformation efficiency.

Identification and expression analysis of OsHsfs in rice.

Heat stress transcription factors (Hsfs) are the central regulators of defense response to heat stress. We identified a total of 25 rice Hsf genes by genome-wide analysis of rice (Oryza sativa L.) genome, including the subspecies of O. japonica and O. indica. Proteins encoded by OsHsfs were divided into three classes according to their structures. Digital Northern analysis showed that OsHsfs were expressed constitutively. The expressions of these OsHsfs in response to heat stress and oxidative stress differed among the members of the gene family. Promoter analysis identified a number of stress-related cis-elements in the promoter regions of these OsHsfs. No significant correlation, however, was found between the heat-shock responses of genes and their cis-elements. Overall, our results provide a foundation for future research of OsHsfs function.

[Establishment and application of AFLP fingerprinting system in Atractylodes macrocephala germplasm].

OBJECTIVE: To establish the AFLP Fingerprinting system in the germplasm of Atractylodes macrocephala Koidz. METHODS: 10 wild or cultivated Atractylodes macrocephala were used for AFLP fingerprinting analysis by EcoRI and MseI restriction enzymes with silver staining. RESULTS: Using 2X CTAB buffer extraction method can obtain the best genomic DNA samples. According to the AFLP polymorphism, sixteen out of forty primer pairs were selected to be suitable for AFLP analysis. Total 3003 polymorphic bands were obtained from the 16 sets of primer. Based on the AFLP results, the 10 samples of Atractylodes macrocephala germplasm were classified into four types. CONCLUSION: The establishment of the AFLP fingerprinting system in Atractylodes macrocephala will be used in the identification of germplasms and breeding of the species.

Molecular and functional comparisons of the vacuolar Na+/H+ exchangers originated from glycophytic and halophytic species.

A novel vacuolar Na+/H+ exchanger, CgNHX1, was cloned from a halophytic species Chenopodium glaucum by using reverse transcriptase-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) technique. Sequence alignment and phylogenetic analysis of 22 NHX genes from GenBank as well as the new CgNHX1 gene indicate that NHX genes shared a great degree of similarity, regardless of their glycophytic or halophytic origin. Expression of the CgNHX1 gene was induced by NaCl and peaked at 400 mmol/L NaCl. Overexpression of NHX1 genes in rice enhanced their tolerance to salt stress. However, there is no significant difference in salt tolerance among the transgenic rice plants overexpressing the NHX1 genes from either glycophytic or halophytic species. The Na+ content of both the wild type (WT) and transgenic plants increased when exposed to 50 and 100 mmol/L NaCl, and the Na+ concentration in transgenic plants was marginally higher than that of WT. Our data demonstrate that the overexpression of the NHX1 gene from either glycophytic or halophytic species resulted in the enhanced tolerance to salt stress at a similar level, suggesting that NHX gene per se might not be the reason accounting for the difference in salt tolerance between glycophytes and halophytes.