The Cl^- homeostasis was known as the major mechanism of soybean to achieve NaCl tolerance, but studies on the role of chloride channel under abiotic stress were relatively few. We cloned a putative CLC-type chloride channel gene GmCLCnt from soybean via RACE and it was predicted to encode a protein of 783 amino acids with 9 possible transmembrane domains and 2 tandem CBS domains. Real-time RT-PCR analysis showed that the GmCLCnt gene was expressed in all tissues of soybean but enriched in leaves and its expression was induced by NaCl, polyethylene glycol （PEG）, coldness and ABA treatments. The Arabidopsis seedlings overexpressing GmCLCnt were more tolerant to higher concentration of NaCl than those of wild type. The results suggested that the GmCLCnt may be a CLC-type chloride channel and play an important role in salt tolerance.
For clarifying the hierarchical patterns of population structure of soybean landraces in China, the seven clusters previously identified using Bayesian clustering of 1 504 soybean landraces based on SSR markers genotyping data were further analyzed. Using the largest value of AK, these landraces could be split into 20 sub-clusters, which was supported by highly significant pairwise Fst-values and generally in accordance with the geographic origin and sowing types. The autumn-sowing types ended up in one distinct sub-cluster from the otherwise summer-sowing type, where the autumn- sowing types are most likely derived from. The division into 20 sub-clusters explained 7.3% of the genetic variation, next to 9.7% present among the seven clusters, 81.1% residing among landraces within sub-clusters, and 1.9% within the landraces. The distribution pattern of genetic diversity among the sub-clusters of each cluster was uneven, with two HSuM sub-clusters （Central China） and some South China sub-clusters showing significantly higher level of genetic diversity.
LI Ying-huiMarinus J M SmuldersCHANG Ru-zhenQIU Li-juan
MicroRNA1511(miR1511) is a small RNA with unknown function identified in several plants by deep sequencing.In this study,we showed that this small RNA is an authentic miRNA by analyzing the structure of the precursor stem-loop containing the newly identified miR1511 * sequence.We confirmed this result by Northern blotting analysis.We used 5'RACE to identify one of the target genes(GmRPL4a) cleaved by both miR1511 and miR1511 *.The site cleaved by miR1511 * was located in the first exon of GmRPL4a,and the site cleaved by miR1511 was located in the second exon.The expression level of miR1511/1511 * was higher in leaves than in roots and stems.In contrast,the lowest level of GmRPL4a expression was in the leaves and the highest in the root.These results indicate that an miRNA can co-regulate with an miRNA * to cleave the same target gene in plants,and that the level of GmRPL4a mRNA is regulated by miR1511/1511 *.
