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Appropriate timing of flowering is critical for reproductive success and necessarily involves complex genetic regulatory networks. A mobile floral signal, called florigen, is a key molecule in this process, and FLOWERING LOCUS T (FT) protein is its major component in Arabidopsis. FT is produced in leaves, but promotes the floral transition in the shoot apex, where it forms a complex with a basic region/leucine-zipper (bZIP) transcription factor, FD. Formation of the florigen complex depends on the supposed phosphorylation of FD; hitherto, however, the responsible protein kinase(s) have not been identified. In this study, we prepared protein extracts from shoot apices of plants around the floral transition, and detected a protein kinase activity that phosphorylates a threonine residue at position 282 of FD (FD T282), which is a crucial residue for the complex formation with FT via 14-3-3. The kinase activity was calcium-dependent. Subsequent biochemical, cellular, and genetic analyses showed that three calcium-dependent protein kinases (CDPKs) efficiently phosphorylate FD T282. Two of them (CPK6 and CPK33) are expressed in shoot apical meristem and directly interact with FD, suggesting they have redundant functions. The loss of function of one CDPK (CPK33) resulted in a weak but significant late-flowering phenotype.

fruits is controlled by two secreted peptides, EPFL2 and EPFL9 (also known as Stomagen), and their receptors from the ERECTA (ER) family that act from the carpel wall and the placental tissue. We found that a signalling pathway controlled by EPFL9 acting from the carpel wall through the LRR-receptor kinases ER, ERL1 and ERL2 promotes fruit growth. Regular spacing of ovules depends on EPFL2 expression in the carpel wall and in the inter-ovule spaces, where it acts through ERL1 and ERL2. Loss of EPFL2 signalling results in shorter fruits and irregular spacing of ovules or even ovule twinning. The EPFL2 expression pattern between ovules is under negative-feedback regulation by auxin, which accumulates in the arising ovule primordia. We propose that the auxin-EPFL2 signalling module evolved to control the initiation and regular, equidistant spacing of ovule primordia, which serves to minimise competition between developing seeds. Together, EPFL2 and EPFL9 coordinate ovule patterning and thereby seed number with fruit growth through a set of shared receptors.Reduction of ovule number observed in er-105 seems to be an indirect consequence of the smaller fruit size and the limited availability of space. The EPFL2 pathway also affects fruit growth, but has a more pronounced impact on the patterning of ovule initial cells and 3 thus increases ovule density (Figure 6A, B).

Detection of ice precipitation is one of the objectives in the Global Precipitation Measurement (GPM) mission. The dual-frequency precipitation radar (DPR) can provide precipitation echoes at two different frequencies, which may enable differentiating solid precipitation echoes from liquid precipitation echoes. A simple algorithm that flags the pixels that contain intense ice precipitation above the height of C is implemented in version 5 of the DPR products. In the inner swath of DPR measurements in which both Ku- and Ka-band radar echoes are available, the measured dual-frequency ratio () together with the measured radar reflectivity factor is used to judge the existence of intense ice precipitation. Comparisons of the flagged pixels with surface measurements show that the algorithm correctly identifies relatively intense ice precipitation regions. The global distribution of the flagged pixels indicates an interesting difference between land and ocean, in particular in the distribution of ice precipitation that reaches the surface. The flag is also expected to be useful for improving precipitation retrieval algorithms by microwave radiometers.

Abstract. To investigate a descent rate in the Antarctic polar vortex, we analyzed the long-lived trace gas data derived from the Halogen Occultation Experiment on board the Upper Atmosphere Research Satellite during the 6-year period from 1992 to 1997. By comparing the Antarctic fall (February and March) and spring (September and October) methane profiles, we estimated the middle stratospheric descent for each of the six winters. Large year-to-year variations are seen (1.2-1.8 km month -• at 0.6 ppmv), which consist of a biennial oscillation and a decreasing trend for the period analyzed. The descent rate is larger in the even years (1992, 1994, and 1996) than in the odd years (1993, 1995, and 1997). Dynamical fields for the 6 years are also analyzed using the United Kingdom Meteorological Office assimilation data. The differences between the even and odd years are clear in the midwinter. In the even years the downward and poleward movement of the westerly jet occurs earlier. The thermal wind relation infers that this event is associated with the development of a "warm pool" around the Antarctic stratopause, resulting from adiabatic heating due to the downward motion of air. Planetary wave activity over the winter season is more vigorous in the even years than in the odd years, suggesting a close relationship between the mean flow and planetary waves. S95 gave a reliable estimation of the vertical descent rate within the Antarctic polar vortex using the trace gas, but the estimation was based on an observation for only one winter. The HALOE has continued measuring tracer fields, and now the data record is long enough to see year-to-year variation of the descent rate. Here we will analyze the HALOE data for the period of 1992-1997 using the same method as S95, paying special attention to the average descent rate during the Antarctic fall to spring and its interannual variability. We will also discuss the relationship to the stratospheric circulation.Because the HALOE measurement reaches high latitudes only twice in a single winter, we can only estimate the "average" descent rate over the winter season. As for the intraseasonal variation in vertical descent, Rosenfield et al. [1994] computed diabatic descent within the vortex using a radiative transfer model and showed that during the winter season the descent rate is almost uniform in the middle and lower stratosphere. Further, Randel et al. [1998] indicated that CH 4 isolines 0.3-0.8 ppmv at equivalent latitude 76øS move down at an almost constant rate over the winter season based on the anal-

Ozone concentration perturbations in the high‐latitude lower stratosphere in the Northern Hemisphere were observed by Improved Limb Atmospheric Spectrometer (ILAS) after the polar vortex breakdown at the beginning of May 1997 and until the end of June of that same year. Simulations and a passive tracer experiment using the Center for Climate System Research/National Institute for Environmental Studies (CCSR/NIES) nudging chemical transport model (CTM) show that the low‐ozone perturbations observed in May were caused by the Arctic polar vortex debris, while those after the end of May resulted from a dynamical elongation due to zonal wave number 2 planetary waves of the low‐ozone region in the summer polar stratosphere, which had been developed by the catalytic ozone destruction cycle of NOX. These low‐O3 air masses of different origin were advected or elongated from the polar region to the ILAS measurement points. An episodic event of a dynamical O3 perturbation in June 1997 on a chemically induced meridional O3 gradient is described. These results show that a timing of the polar vortex breakdown and activity of planetary waves after the breakdown may affect the O3 background gradient in the summer lower stratosphere at middle and high latitudes.

Plant posture is controlled by various environmental cues, such as light, temperature, and gravity. The overall architecture is determined by the growth angles of lateral organs, such as roots and branches. The branch growth angle affected by gravity is known as the gravitropic setpoint angle (GSA), and it has been proposed that the GSA is determined by balancing two opposing growth components: gravitropism and anti-gravitropic offset (AGO). The molecular mechanisms underlying gravitropism have been studied extensively, but little is known about the nature of the AGO. Recent studies reported the importance of LAZY1-LIKE (LZY) family genes in the signaling process for gravitropism, such that loss-of-function mutants of LZY family genes resulted in reversed gravitropism, which we term it here as the “anti-gravitropic” phenotype. We assume that this peculiar phenotype manifests as the AGO due to the loss of gravitropism, we characterized the “anti-gravitropic” phenotype of Arabidopsis lzy multiple mutant genetically and physiologically. Our genetic interaction analyses strongly suggested that gravity-sensing cells are required for the “anti-gravitropic” phenotype in roots and lateral branches. We also show that starch-filled amyloplasts play a significant role in the “anti-gravitropic” phenotype, especially in the root of the lzy multiple mutant.

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