These authors contributed equally to this work. SUMMARYAbscisic acid (ABA) and gibberellins (GAs) are plant hormones which antagonistically mediate numerous physiological processes, and their optimal balance is essential for normal plant development. However, the molecular mechanism underlying ABA and GA antagonism still needs to be determined. Here, we report that ABA-INSENSITIVE 4 (ABI4) is a central factor in GA/ABA homeostasis and antagonism in post-germination stages. ABI4 overexpression in Arabidopsis (OE-ABI4) leads to developmental defects including a decrease in plant height and poor seed production. The transcription of a key ABA biosynthetic gene, NCED6, and of a key GA catabolic gene, GA2ox7, is significantly enhanced by ABI4 overexpression. ABI4 activates NCED6 and GA2ox7 transcription by directly binding to the promoters, and genetic analysis revealed that mutation in these two genes partially rescues the dwarf phenotype of ABI4 overexpressing plants. Consistently, ABI4 overexpressing seedlings have a lower GA/ABA ratio than the wild type. We further show that ABA induces GA2ox7 transcription while GA represses NCED6 expression in an ABI4-dependent manner; and that ABA stabilizes the ABI4 protein whereas GA promotes its degradation. Taken together, these results suggest that ABA and GA antagonize each other by oppositely acting on ABI4 transcript and protein levels.

Iron-sulfur proteins are ubiquitous in living organisms. Their pervasive occurrence and multiplicity of function are comparable to other biological prosthetic groups such as hemes and flavins (1, 2). Ironically, iron-sulfur proteins are highly sensitive to reactive free radicals such as nitric oxide (3). When purified iron-sulfur proteins are treated with nitric oxide in vitro, the iron-sulfur clusters are modified forming proteinbound dinitrosyl iron complexes that have a characteristic EPR signal at g av ϭ 2.04 (4 -6). The same EPR signal at g av ϭ 2.04 has been observed in activated macrophages (7-9), indicating that the protein dinitrosyl iron complexes may be produced by nitric oxide physiologically. Direct isolation of ferredoxin protein from the Escherichia coli cells treated with nitric oxide demonstrated that up to 40% overproduced ferredoxin clusters are converted to the ferredoxin dinitrosyl iron complex (10). Many iron-sulfur proteins become inactivated when their iron-sulfur clusters are modified (4 -6, 11, 12). Using isolated aconitases from mammalian cells, the interrelation between formation of the dinitrosyl iron complex and inactivation of the enzyme activity has been quantitatively demonstrated (6). In some cases, iron-sulfur proteins are considered the nitric oxide sensor (12)(13)(14). For example, the redox transcription factor SoxR of E. coli is switched on when the SoxR [2Fe-2S] cluster is modified by nitric oxide forming the SoxR dinitrosyl iron complex (14).Although the protein dinitrosyl iron complexes are stable in vitro, they are efficiently repaired in aerobically growing E. coli cells even in the presence of the protein synthesis inhibitor chloramphenicol (10,14). This observation is consistent with a previous report (15) that proteins with modified iron-sulfur clusters are not degraded; rather the modified iron-sulfur clusters are repaired in E. coli cells. Surprisingly, when intact E. coli cells are disrupted, the protein dinitrosyl iron complexes become very stable (10), suggesting that the specific cellular activity for repairing the protein dinitrosyl iron complexes is inactivated in the cell extracts. We proposed that repair of the protein dinitrosyl iron complexes requires cellular reducing equivalents, which are oxidized and diluted when intact E. coli cells are disrupted. In a search for such reducing equivalents, we found that L-cysteine, but not N-acetyl-L-cysteine or reduced glutathione, can effectively decompose the protein dinitrosyl iron complexes in the cell extracts prepared from the E. coli cells treated with nitric oxide (10). Furthermore, L-cysteine is equally effective in decomposing the purified protein dinitrosyl iron complexes, implying that other cellular components are not needed for the reaction (10). Nevertheless, the mechanism for the L-cysteine-mediated decomposition of the protein dinitrosyl iron complexes is not fully understood. One hypothesis we postulated is that L-cysteine removes the nitric oxide moieties from the dinitrosyl iron complexes, leav...

Highlight FLC is the direct target of both of the transcription factors ABI4 and ABI5, and ABA inhibits floral transition by activating FLC transcription through ABI4.

Auxin is an important phytohormone which mediates diverse development processes in plants. Published research has demonstrated that auxin induces seed dormancy. However, the precise mechanisms underlying the effect of auxin on seed germination need further investigation, especially the relationship between auxins and both abscisic acid (ABA) and gibberellins (GAs), the latter two phytohormones being the key regulators of seed germination. Here we report that exogenous auxin treatment represses soybean seed germination by enhancing ABA biosynthesis, while impairing GA biogenesis, and finally decreasing GA1/ABA and GA4/ABA ratios. Microscope observation showed that auxin treatment delayed rupture of the soybean seed coat and radicle protrusion. qPCR assay revealed that transcription of the genes involved in ABA biosynthetic pathway was up-regulated by application of auxin, while expression of genes involved in GA biosynthetic pathway was down-regulated. Accordingly, further phytohormone quantification shows that auxin significantly increased ABA content, whereas the active GA1 and GA4 levels were decreased, resulting insignificant decreases in the ratiosGA1/ABA and GA4/ABA.Consistent with this, ABA biosynthesis inhibitor fluridone reversed the delayed-germination phenotype associated with auxin treatment, while paclobutrazol, a GA biosynthesis inhibitor, inhibited soybean seed germination. Altogether, exogenous auxin represses soybean seed germination by mediating ABA and GA biosynthesis.

As a traditional soybean product with good quality and a healthy food with many functional components, tofu is increasingly consumed in people's daily life. Traditional tofu processing consists of numerous steps, including the soaking and grinding of soybean seeds, heating of the soybean slurry, filtering, and addition of coagulants, and others. The properties of soybean seeds, processing scale, soaking and heating conditions, type and concentration of coagulant, and other factors collectively impact the processing steps and the final tofu quality. The generation of whole soybean tofu with more nutritive value comparing with traditional tofu has been successfully reported by several studies. As one of the most important functional component, isoflavones and their presence in tofu are also influenced by the above-mentioned factors, which influence the nutritive value of tofu. Research investigating the influence of tofu processing conditions on the quality and isoflavone profiles of tofu are the subject of this review. Issues that should be further studied to investigate the influence of processing conditions on the quality and nutritive value of tofu are also introduced.

Traditional maize (Zea mays L.) and soybean (Glycine max (L) Merrill) intercropping practice cannot be adapted to modern agriculture due to low light use efficiency, radiation use efficiency, low comparative profits of soybeans and incompatibility with mechanization. However, a new type of maize and soybean intercropping system (MSIS) with high land equivalent ratio (LER) provides substantial benefits for small-land hold farmers worldwide. Our research team has done a wide range of research to suggest the appropriate planting geometry that ensures high yield and LER as high as 2.36, nutrient acquisition and mechanical operations in MSISs. Increase in the distance between soybean and maize rows and decrease in the spacing of maize narrow rows is useful for the high light interception for the short soybean in MSISs. This review concludes that MSIS has multifold and convincing results of LER and compatible with mechanization, while those practiced other than China still require technological advancements, agronomic measures and compatible mechanization to further explore its adaptability.

Three novel Zn(II) complexes containing either 2,2',2"-tripyridylamine (2,2',2"-tpa) or 2,2',3"-tripyridylamine (2,2',3"-tpa) have been synthesized and structurally characterized. Compound 1, Zn(2,2',2"-tpa)Cl2, has a tetrahedral geometry while compounds 2, Zn(2,2',2"-tpa)2(O2CCF3)2, and 3, Zn(2,2',3"-tpa)4(O2CCF3)2, have an octahedral geometry. The 2,2',2"-tpa ligand in 1 and 2 functions as a bidentate ligand, chelating to the zinc center, while the 2,2",3"-tpa ligand in 3 functions as a terminal ligand, binding to the zinc center through the 3-pyridyl nitrogen atom. All three compounds emit a blue color in solution and in the solid state. The emission maxima for the three compounds in solution are at lambda = 422, 426, and 432 nm, respectively. The blue luminescence of the complexes is due to a pi *-->pi transition of the tpa ligand as established by an ab initio calculation on the free ligand 2,2',2"-tpa and complex 1. Compounds 1 and 2 are fluxional in solution owing to an exchange process between the coordinate and noncoordinate 2-pyridyl rings of the 2,2',2"-tpa ligand. Compound 2 is also fluxional owing to a cis-trans isomerization process, as determined by variable-temperature 1H NMR spectroscopic analysis.

Soybean seeds contain higher concentrations of oil (triacylglycerol) and fatty acids than do cereal crop seeds, and the oxidation of these biomolecules during seed storage significantly shortens seed longevity and decreases germination ability. Here, we report that diethyl aminoethyl hexanoate (DA-6), a plant growth regulator, increases germination and seedling establishment from aged soybean seeds by increasing fatty acid metabolism and glycometabolism. Phenotypic analysis showed that DA-6 treatment markedly promoted germination and seedling establishment from naturally and artificially aged soybean seeds. Further analysis revealed that DA-6 increased the concentrations of soluble sugars, during imbibition of aged soybean seeds. Consistently, the concentrations of several different fatty acids in DA-6-treated aged seeds were higher than those in untreated aged seeds. Subsequently, qPCR analysis indicated that DA-6 induced the transcription of several key genes involved in the hydrolysis of triacylglycerol to sugars in aged soybean seeds. Furthermore, the activity in aged seeds of invertase, which catalyzes the hydrolysis of sucrose to form fructose and glucose, increased following DA-6 treatment. Altogether, DA-6 promotes germination and seedling establishment from aged soybean seeds by enhancing the hydrolysis of triacylglycerol and the conversion of fatty acids to sugars.