Phosphorylation of DUF1639 protein by osmotic stress/ABA-activated protein kinase 10 regulates abscisic acid-induced antioxidant defense in rice.

In rice (Oryza Sativa), Osmotic Stress/ABA-activated Protein Kinase 10 (SAPK10) has been shown to be induced by hyperosmotic stress and abscisic acid (ABA). However, the molecular function of SAPK10 and its downstream targets in ABA-induced antioxidant defense is poorly understood. Here, we identified an unknown function DUF1639 family protein, OsDUF1639.1, which interacts with SAPK10 in vitro and in vivo. OsDUF1639.1 positively regulates ABA responses in seed germination and tolerance to drought stress. We found that SAPK10 directly phosphorylates OsDUF1639.1 at Thr-80 in vitro. The transient expression analysis in combination with mutant analysis in rice protoplasts showed that Thr-80 is essential for ABA-induced stimulation of antioxidant defense by SAPK10. These results suggest that SAPK10 functions upstream of OsDUF1639.1 to regulate the activities of antioxidant enzymes, and Thr-80 phosphorylation of OsDUF1639.1 has a crucial role in ABA-induced antioxidant defense.

Rice calcium/calmodulin-dependent protein kinase directly phosphorylates a mitogen-activated protein kinase kinase to regulate abscisic acid responses.

Calcium (Ca2+)/calmodulin (CaM)-dependent protein kinase (CCaMK) is an important positive regulator of abscisic acid (ABA) and abiotic stress signaling in plants and is believed to act upstream of mitogen-activated protein kinase (MAPK) in ABA signaling. However, it is unclear how CCaMK activates MAPK in ABA signaling. Here, we show that OsDMI3, a rice (Oryza sativa) CCaMK, directly interacts with and phosphorylates OsMKK1, a MAPK kinase (MKK) in rice, in vitro and in vivo. OsDMI3 was found to directly phosphorylate Thr-25 in the N-terminus of OsMKK1, and this Thr-25 phosphorylation is OsDMI3-specific in ABA signaling. The activation of OsMKK1 and its downstream kinase OsMPK1 is dependent on Thr-25 phosphorylation of OsMKK1 in ABA signaling. Moreover, ABA treatment induces phosphorylation in the activation loop of OsMKK1, and the two phosphorylations, in the N-terminus and in the activation loop, are independent. Further analyses revealed that OsDMI3-mediated phosphorylation of OsMKK1 positively regulates ABA responses in seed germination, root growth, and tolerance to both water stress and oxidative stress. Our results indicate that OsMKK1 is a direct target of OsDMI3, and OsDMI3-mediated phosphorylation of OsMKK1 plays an important role in activating the MAPK cascade and ABA signaling.

An Efficient System for Ds Transposon Tagging in Brachypodium distachyon.

Transposon tagging is a powerful tool that has been widely applied in several species for insertional mutagenesis in plants. Several efforts have aimed to create transfer-DNA (T-DNA) insertional mutant populations in Brachypodium distachyon, a monocot plant used as a model system to study temperate cereals, but there has been a lack of research aimed at using transposon strategies. Here, we describe the application of a maize (Zea mays) Dissociation (Ds) transposon tagging system in B distachyon The 35S::AcTPase cassette and Ds element were constructed within the same T-DNA and transformed into B distachyon plants. The Ds element was readily transposed to other chromosomes or to the same chromosome under the function of Activator (Ac) transposase. Through homologous chromosome synapsis, recombination, and segregation, the Ds element separated from the Ac element. We selected stable Ds-only plants using G418 and GFP assays and analyzed 241 T0 lines, some of which were highly efficient at producing Ds-only progeny. Through thermal asymmetric interlaced PCR, we isolated 710 independent Ds flanking sequences from Ds-only plants. Furthermore, we identified a large collection of mutants with visible developmental phenotypes via this transposon tagging system. The system is relatively simple and rapid in comparison to traditional T-DNA insertion strategies, because once efficiency lines are obtained they can be reused to generate more lines from nontransposed plants without the use of time-consuming tissue culture steps.

[Synthesis and luminescence of methyl-phenacyl sulfoxide complexes with heavy rare earth perchlorate].

RE(ClO4)3 x L5 x C2H5OH(RE=Gd, Tb, Dy, Tm, Yb; L = C6H5COCH2SOCH3) complexes were synthesized. The composion of the complexes was determined by elemental analysis, coordination titration, molar conductivities, and TGA studies. The ligand and coordination compounds were studied by means of IR spectra, 1H NMR, and the Tb(II) coordination compound was studied by means of phosphorescence spectra, and fluorescence excitation and emission spectra. Each energy level of Tb3+ was calculated according to the fluorescent emission spectra results.