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Previous studies in Arabidopsis reported that the PPR protein SOAR1 plays critical roles in plant response to salt stress. In this study, we reported that expression of the Arabidopsis SOAR1 (AtSOAR1) in rice significantly enhanced salt tolerance at seedling growth stage and promoted grain productivity under salt stress without affecting plant productivity under non-stressful conditions. The transgenic rice lines expressing AtSOAR1 exhibited increased ABA sensitivity in ABA-induced inhibition of seedling growth, and showed altered transcription and splicing of numerous genes associated with salt stress, which may explain salt tolerance of the transgenic plants. Further, we overexpressed the homologous gene of SOAR1 in rice, OsSOAR1, and showed that transgenic plants overexpressing OsSOAR1 enhanced salt tolerance at seedling growth stage. Five salt- and other abiotic stress-induced SOAR1-like PPRs were also identified. These data showed that the SOAR1-like PPR proteins are positively involved in plant response to salt stress and may be used for crop improvement in rice under salinity conditions through transgenic manipulation. [ABSTRACT FROM AUTHOR]

Key message: The kinase-associated protein phosphatase, KAPP, is negatively involved in abscisic acid (ABA) signaling. KAPP interacts physically with SnRK2.2, SnRK2.3 and SnRK2.6, and functionally acts upstream of SnRK2.2 and SnRK2.3. The kinase-associated protein phosphatase (KAPP) has been reported to be involved in the regulation of many developmental and signaling events, but it remains unknown whether KAPP is involved in ABA signaling. Here, we report that KAPP is negatively involved in ABA-mediated seed germination and early seedling growth in Arabidopsis thaliana. The two loss-of-function mutants of KAPP, kapp-1 and kapp-2, exhibit increased ABA sensitivity in ABA-induced seed germination inhibition and post-germination growth arrest. The three closely-related protein kinase, (SNF1)-related protein kinase SnRK2.2, SnRK2.3 and SnRK2.6, which play critical roles in ABA signaling, interact and co-localize with KAPP. Genetic evidence showed that the ABA-hypersensitive phenotypes caused by KAPP mutation were suppressed by the double mutation of SnRK2.2 and SnRK2.3, indicating that KAPP functions upstream of SnRK2.2 and SnRK2.3 in ABA signaling. RNA-sequencing analysis revealed that KAPP mutation affects expression of multiple ABA-responsive genes. These results demonstrated that KAPP is negatively involved in plant response to ABA, which help to understand the complicated ABA signaling mechanism. [ABSTRACT FROM AUTHOR]

Quantitative trait loci (QTL) for the length of the dehiscence that forms at the base of the anther [basal dehiscence length (BDL)] in rice ( Oryza sativa L.) were analyzed using chromosome segment substitution lines (CSSLs) developed from 9311 (as the recipient) and Nipponbare (as the donor). Using composite interval mapping with QTL Icimapping software, seven QTLs were detected on Chr. 2, 7, 8, 9, 10, and 11. These QTLs explained 6.49-18.15 % of the total phenotypic variation for BDLin CSSLs during 2012. qBDL8, qLDB10 and qBDL11 were derived from 9311 allele. The other four QTLs had negative effects on BDL and were derived from Nipponbare alleles. qBDL2- 2, qBDL7, qBDL8, qBDL10 and qBDL11 were consistent with some heat tolerance QTLs mapped with different indexes and populations by other researchers. Among them, qBDL2-2 and qBDL10 were found to have significant effect on heat tolerance in populations derived from Nipponbare in previous reports, which suggests that those two QTLs were stable in different environments and can be used in heat tolerance breeding. The results indicated that QTL analysis of the long basal dehisce trait might be an effective index to identify the heat tolerance of rice in an ordinary environment. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deficiency is a major yield-limiting factor in rice production. The objective of this study was to identify putative QTLs for low-N stress tolerance of rice, using an advanced backcross population derived from crosses between an indica cultivar '93-11' and a japonica cultivar 'Nipponbare' and genotyped at 250 marker loci. Plant height, maximum root length, root dry weight, shoot dry weight and plant dry weight under two N conditions and their relative traits were used to evaluate low-N tolerance at the seedling stage. A total of 44 QTLs were identified on chromosomes 1, 2, 3, 4, 5, 6, 8 and 9. Eight intervals on five chromosomes were identified to harbour multiple QTLs, suggesting pleiotropism or multigenic effects according to the contributor of alleles. Some QTL clusters were found in the nearby regions of genes associated with N recycling in rice, indicating that the key N metabolism genes might have effects on the expression of QTLs. Several unique QTLs for relative traits were detected, which suggested the specific genetic basis of relative performance. [ABSTRACT FROM AUTHOR]

Metabolomic and transcriptomic profiling data were obtained and integrated to elucidate the crucial network controls on taxol and its precursor biosynthesis during the taxane core functionalization within methyl jasmonate (MJ)-induced Taxus chinensis cells. Twelve metabolites were identified using liquid chromatography-electrospray ionization-mass spectrometry. These metabolites contain taxol (paclitaxel), baccatin III (B-III) and its analogs, a group structurally bearing multiple free hydroxyls (TAX), and another group of multiple acyl taxanes (MAT), including taxuyunnanine C (TC) and its analogs. The metabolomic profile showed a higher increase in TAX than in MAT. Particularly, the ratio of B-III and taxol to the total taxane content increased more significantly in TAX than in MAT. The MAT proportion did not significantly change, although they are predominant components in cell cultures compared with TAX. Quantitative real-time polymerase chain reaction (qRT-RCR) was used to determine the transcription level of 20 genes, among which 11 were reported responsible for taxol biosynthesis and 9 were obtained from our previous transcriptomic data. The total expression levels of hydroxylase after 24 h and 6 days were higher than those of acylase. The principal component analysis (PCA) results validated the metabolomic analysis data, indicating that hydroxylation was more crucial than acylation for controlling the flux toward TAX biosynthesis. Furthermore, the PCA contribution comparison showed that two undefined genes of OHX1 and ACX3 might have good potential in TAX upregulation and MAT downregulation. To the best of our knowledge, this study provides the first experimental evidence on the contribution of total hydroxylation to taxane biosynthesis. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:269-280, 2014 [ABSTRACT FROM AUTHOR]

Two new dammarane-type compounds were isolated from the leaves and stems of Panax quinquefolium L. The new compounds were named as pseudo-ginsenoside RT6 (1) and pseudoginsengenin R1 (2). The structures of the new compounds were elucidated by the combined analysis of NMR and HR-ESI-MS as (20S,24R)-6-O-β-d-glucopyranosyl-dammar-3-one-20,24-epoxy-6α,12β,25-triol (1) and (20S,24R)-dammar-3-one-20,24-epoxy-6α,12β,25-triol (2). [ABSTRACT FROM AUTHOR]