Genome-Wide Analyses of the Soybean F-Box Gene Family in Response to Salt Stress.

The F-box family is one of the largest gene families in plants that regulate diverse life processes, including salt responses. However, the knowledge of the soybean F-box genes and their roles in salt tolerance remains limited. Here, we conducted a genome-wide survey of the soybean F-box family, and their expression analysis in response to salinity via in silico analysis of online RNA-sequencing (RNA-seq) data and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) to predict their potential functions. A total of 725 potential F-box proteins encoded by 509 genes were identified and classified into 9 subfamilies. The gene structures, conserved domains and chromosomal distributions were characterized. There are 76 pairs of duplicate genes identified, including genome-wide segmental and tandem duplication events, which lead to the expansion of the number of F-box genes. The in silico expression analysis showed that these genes would be involved in diverse developmental functions and play an important role in salt response. Our qRT-PCR analysis confirmed 12 salt-responding F-box genes. Overall, our results provide useful information on soybean F-box genes, especially their potential roles in salt tolerance.

[Numerical analysis of morphological variation of germplasm resources of dioscorea].

OBJECTIVE: Botanical characters of germplasm resources of Dioscorea were observed and compared, which could to offer reference for its genetic improvement, germplasm resource identification and classification. METHOD: Based on field cultivation, twenty-four morphological traits of ninety-four Dioscorea germplasm resources were observed or determined. And the morphological differences among germplasm resources were compared by principal component analysis and cluster analysis. RESULT: There were ample morphological diversity in the twenty-four traits, in especially in leaf size and tuber characters of the ninety-four Dioscorea germplasm resources. The first seven principal components which accounted for 80. 957% of total variance were extracted from the principal component analysis. The ninety-four germplasm resources could be divided into four clusters, which belonging to Dioscorea opposite, D. persimili, D. fordii and D. alata respectively. CONCLUSION: There were large morphological variation among germplasm resources on Dioscorea. Identification of germplasm resources of Dioscorea should focus on leaf size and tuber characters.

[Genetic analysis and gene mapping of cold-induced seedling chlorosis in rice].

We found that the seedlings of indica rice cultivar Dular showed chlorosis but the seedlings of japonica rice cultivar Lemont remained green under natural low temperature in early spring. Using an F2 population of Lemont Dular, we found that the difference of cold tolerance at seedling stage between Dular and Lemont is controlled by a single major gene, with the chlorosis allele being recessive. We named the gene cisc(t). With the help of SSR markers, cisc(t) was mapped in a 5.5 cM interval between SSR markers RM257 and RM242 on chromosome 9.

[Assesment of genetic diversity of allelopathic rice germplasm based on RAPD and ISSR].

Random Amplified Polymorphic DNA (RAPD) and Inter-simple Sequence Repeat (ISSR) methods were used to detect the genetic diversity of 57 allelopathic rice accessions which were introduced from 10 countries or areas. A total of 12 RAPD primers and seven ISSR primers were indentified with polymorphism among the entries. For RAPD markers, 85 polymorphic bands were produced, percentage of polymorphic bands (PPB) were 69.4%. For ISSR marker, 34 polymorphic bands were generated, PPB were 53.0%. The result from the clustering analysis by UPGMA indicated that those accessions from the same geographical location were clustered into one group. It was also found that some rice accessions with higher allelopathic potential were clustered together, implying that the genes conferring allelopathy in those rice accessions might be isolocus. However, some rice accessions with different allelopathic potential clustered into the same group performed lower level of generic polymorphism which was attributed to oriented selection for other traits in breeding program. The estimates of correlation coefficient of RAPD and ISSR based on the genetic similarity matrices were significantly correlated.

[Differential protein analysis on the root response of rice with high phosphorous uptake efficiency to low phosphorous stress].

A comparative proteomics analysis was performed to identify the molecular response of a rice cultivar (Oryza sative cv. 'IRRI71331') with high phosphorous (P) uptake efficiency to low P stress. The hydroponically grown rice plants were provided with two levels of P (0.5 mg x L(-1) and 10 mg x L(-1)) supplied in quarter strength Kimura solution, and the root total proteins extracted on the 3rd and 6th day of treatments were separated by two-dimensional gel electrophoresis (2-DE). Comparing with the control (10 mg x L(-1) of P), a total of 29 protein spots under low P stress (0.5 mg x L(-1)) showed differences in their relative abundance, among which, 17 were higher, 11 were lower, and 1 was novel on the 3rd day, and 8 were induced, 19 were suppressed, 1 was disappeared, and 1 had no obvious change on the 6th day. Ten differentially expressed protein spots were identified by MALDI-TOF/MS, and searched in protein databases. According to the putative functions, the identified proteins were classified into four groups, i.e., signal transduction (glycine-rich RNA-binding protein, phosphate starvation response regulator-like), gene expression (putative pre-mRNA splicing factor, putative AAA-metalloprotease), metabolism (adenylosuccinate lyase, serpin, S-adenosylmethionine synthetase, MYB transcription factor-like protein), and ion transport (cation-transporting ATPase, sarcoplasmic reticulum protein). The identified proteins were involved in various physiological responses to enhance stress resistance, such as signal recognition and transduction, RNA cleavage, degradation of denatured protein, and ion transportation and cellular ion balance. The serine protease inhibitor and S-adenosylmethionine synthetase and the MYB transcription factor-like protein, which were the key proteins associated with P deficiency--tolerance of other species, were affected by the same stress for rice. The results indicated that the tolerance to low P stress was controlled by a complex signal transduction and metabolism regulation network in rice root system.