Research progress on identification of QTLs and functional genes involved in salt tolerance in soybean.

The yield of soybean is substantially reduced when the crop is grown in salinity-affected soil. This review summarizes the progress achieved in defining the genetic basis of salinity tolerance. Both forward (uncovering the genetic basis of a phenotype by exploiting natural or induced mutations) and reverse (defining the phenotype which arises as a result of an altered DNA sequence) genetics methods have been used to reveal the function of key salinity response genes. Quantitative trait locus analysis has identified six regions of the genome which harbor loci influencing salinity tolerance, and positional cloning has succeeded in isolating one important salt tolerant gene. Meanwhile the application of the genome-wide association study technique has led to the isolation of a second gene involved in salinity tolerance. Reverse genetics experiments have highlighted a number of salinity response genes, mainly including ion transporter genes and transcription factor genes. These studies lay the foundations for understanding the mechanistic basis of salinity tolerance in soybean, knowledge of which would be essential to enable the breeding of highly salinity tolerant soybean cultivars through the use of marker-assisted selection or transgenesis.

[Auxin response factors and plant growth and development].

An important aspect of studies on auxin is auxin response factors (ARFs), which activate or repress the auxin response genes by binding to auxin response elements (AuxREs) on their promoters. In this review, we focused on molecular biological advances of plant ARF families, and discussed ARF structures, regulation of ARF gene expression, the roles of ARFs in regulating the development of plants and in signal transduction and the mechanisms involved in the target gene regulation by ARFs. The phylogenetic relationships of ARFs in plants are close and most of them have 4 domains. ARFs are expressed in various tissues. Their expressions are regulated at both transcriptional and post-transcriptional levels. They play important roles in the interactions between auxin and other hormones.

[The characteristics of nuclear/cytoplasmic genomes of asymmetric somatic hybrid of Daucus carota var. sativa and Swertia mussotii].

Protoplasts of Swertia mussotii irradiated by ultra-violet light (UV) 260 microW/cm(2) were fused with protoplasts of Daucus carota var. sativa using the PEG method. Analysis of 5S rDNA spacer sequences and random amplified polymorphic DNA (RAPD) showed the presence and combination of nuclear DNA from both parents. All hybrids mainly contained genomes of D. carota (receptor) RAPD bands, and a few donor RAPD bands of S. mussotii. There is no obvious relationship between the nuclear DNA composition was not affected by UV-dosage. SSR analysis of chloroplast DNA of the hybrid clones further revealed that cpDNAs of the parents were integrated and recombined in the hybrids randomly.

[Somatic hybridization between carrot and Bupleurum scorzonerifolium and esteras isoenzyme analysis].

OBJECTIVE: To transfer the effective elements of Bupleurum scorzonerifolium into carrot, and provide theoretical data for the exploitation, improvement and selection of the germplasm of Chinese medicinal plants. METHOD: The protoplasta of Bupleurum scorzonerifolium irradiated by ultraviolet light (UV) at an intensity of 300 microW.(cm2)-1 for 0, 1, 2 min respectively were fused with those of carrot Fisch by PEG method. The regenerated clones, derived form a single fused cell, were examined for their hybrid nature by phenotype and Esterase isoenzyme analysis. RESULT: Nine clones were identified as the somatic hybrids between B. scorzonerifolium and carrot. CONCLUSION: This provides a firm foundation for the further analysis of the main active components saikosaponin of somatic hybrids and the screening out of high-medicine-content hybrid cell lines.