Previous study showed that the magnesium-protoporphyrin IX chelatase H subunit (CHLH/ABAR) positively regulates abscisic acid (ABA) signaling. Here, we investigated the functions of a CHLH/ABAR interaction protein, the chloroplast co-chaperonin 20 (CPN20) in ABA signaling in Arabidopsis thaliana. We showed that down-expression of the CPN20 gene increases, but overexpression of the CPN20 gene reduces, ABA sensitivity in the major ABA responses including ABA-induced seed germination inhibition, postgermination growth arrest, promotion of stomatal closure and inhibition of stomatal opening. Genetic evidence supports that CPN20 functions downstream or at the same node of CHLH/ABAR, but upstream of the WRKY40 transcription factor. The other CPN20 interaction partners CPN10 and CPN60 are not involved in ABA signaling. Our findings show that CPN20 functions negatively in the ABAR-WRKY40 coupled ABA signaling independently of its co-chaperonin role, and provide a new insight into the role of co-chaperones in the regulation of plant responses to environmental cues.Electronic supplementary materialThe online version of this article (doi:10.1007/s11103-013-0082-8) contains supplementary material, which is available to authorized users.

In order to study the effects of 200 μmol/L SNP for 1, 3, 5, 7 d on the growth and the enzymes related to nitrogen metabolism under low temperature stress 12/6℃, day/night, and to explore the feasibility of exogenous SNP regulating low temperature stress on melon (Cumumis melo. L) seedlings, the melon seedlings were used as experimental materials and cultivated by substrate culture method. NO donor sodium nitroprusside (SNP) was sprayed on the leaves. The results showed that with the prolongation of low temperature stress, the seedlings growth and nitrogen metabolism were inhibited to some extent. After treatment with exogenous SNP , the seedlings growth (leaf area, shoot fresh weight and root fresh weight) , the contents of nitrate nitrogen, free amino acid, soluble protein and the activities of key enzymes of nitrogen metabolism (NR, NiR, GS, GDH, GOGAT and AS) were all greatly improved; the contents of ammonium nitrogen, the accumulation of H2O2 and the production rate of superoxide anion radical (O2 -) decreased dramatically. In summary, the application of exogenous SNP can effectively alleviate the inhibition of low temperature stress on the growth and nitrogen metabolism, and enhance its low temperature tolerance. The longer the stress, the more obvious the effect.

In Chinese National Soybean GeneBank (CNSGB), we have collected more than 30,000 soybean accessions. However, data sharing for soybean remains an especially sensitive question, and how to share the genome variations within rule frame has been bothering the soybean germplasm workers for a long time. Here we release a big data source named Soybean Functional Genomics & Breeding database (SoyFGB v2.0) (https://sfgb.rmbreeding.cn/), which embed a core collection of 2,214 soybean resequencing genome (2K-SG) from the CNSGB germplasm. This source presents a unique example which may help elucidating the following three major functions for multiple genome data mining with general interests for plant researchers. 1) On-line analysis tools are provided by the Analysis module for haplotype mining in high-throughput genotyped germplasms with different methods. 2) Variations for 2K-SG are provided in SoyFGB v2.0 by Browse module which contains two functions of SNP and InDel. Together with the Gene (SNP & InDel) function embedded in Search module, the genotypic information of 2K-SG for targeting gene / region is accessible. 3) Scaled phenotype data of 42 traits, including 9 quality and 33 quantitative traits are provided by SoyFGB v2.0. With the scaled-phenotype data search and seed request tools under a control list, the germplasm information could be shared without direct downloading the unpublished phenotypic data or information of sensitive germplasms. In a word, the mode of data mining and sharing underlies SoyFGB v2.0 may inspire more ideas for works on genome resources of not only soybean but also the other plants.

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