Salinity causes osmotic stress to crops and limits their productivity. To understand the mechanism underlying soybean salt tolerance, proteomics approach was used to identify phosphoproteins altered by NaCl treatment. Results revealed that 412 of the 4698 quantitatively analyzed phosphopeptides were significantly up-regulated on salt treatment, including a phosphopeptide covering the serine 59 in the transcription factor GmMYB173. Our data showed that GmMYB173 is one of the three MYB proteins differentially phosphorylated on salt treatment, and a substrate of the casein kinase-II. MYB recognition sites exist in the promoter of flavonoid synthase gene GmCHS5 and one was found to mediate its recognition by GmMYB173, an event facilitated by phosphorylation. Because GmCHS5 catalyzes the synthesis of chalcone, flavonoids derived from chalcone were monitored using metabolomics approach. Results revealed that 24 flavonoids of 6745 metabolites were significantly up-regulated after salt treatment. We further compared the salt tolerance and flavonoid accumulation in soybean transgenic roots expressing the 35S promoter driven cds and RNAi constructs of GmMYB173 and GmCHS5, as well as phospho-mimic (GmMYB173S59D) and phospho-ablative (GmMYB173S59A) mutants of GmMYB173. Overexpression of GmMYB173S59D and GmCHS5 resulted in the highest increase in salt tolerance and accumulation of cyaniding-3-arabinoside chloride, a dihydroxy B-ring flavonoid. The dihydroxy B-ring flavonoids are more effective as anti-oxidative agents when compared with monohydroxy B-ring flavonoids, such as formononetin. Hence the salt-triggered phosphorylation of GmMYB173, subsequent increase in its affinity to GmCHS5 promoter and the elevated transcription of GmCHS5 likely contribute to soybean salt tolerance by enhancing the accumulation of dihydroxy B-ring flavonoids.

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SummaryProtein research is generally recognized as experimental science and knowledge of protein science is not constructed axiomatically. In this article, we show that much of our present knowledge of protein science is explainable by principles of protein thermodynamic structure theory. A deductive system for protein knowledge has been developed and several fundamental questions of protein science can be theoretically resolved.2009 IUBMB IUBMB Life, 61(6): [600][601][602][603][604][605][606] 2009

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Growth styles of shelf-margin clinoforms are reliable but understudied predictors of sand-and sediment-budget partitioning into and across the shelf. Three discrete clinoform-growth styles were recognized, including (1) strongly progradational shelf-margin clinoforms with low growth-trajectory angles (G ct ,), low aggradation to progradation ratios (A/P), low clinoform heights (H c ), and long clinoform length (L c ); (2) mixed progradational and aggradational shelf-margin clinoforms with moderate G ct , moderate A/P, intermediate H c , and moderate L c ; and (3) strongly aggradational clinoforms with high G ct , high A/P, high H c , and short L c .In the South China Sea dataset considered, strongly progradational shelf-margin clinoforms exhibit flat progradational and at times a mildly aggrading stacking patterns, whereas mixed progradational and aggradational clinoforms display stacking patterns with significant progradation and aggradation. Strongly aggradational shelf-margin clinoforms are dominated by aggradational stacking patterns. Each clinoform-growth style therefore represents a specific stratal stacking pattern, providing an important tool for approaching a model-independent methodology in sequence stratigraphy.In the study dataset, strongly progradational and strongly aggradational shelf-margin clinoforms are fronted by sand-prone submarine fan systems with high sand-shale ratios and mud-dominated mass-transport systems with low sand-shale ratios, respectively. Mixed progradational and aggradational clinoforms are associated with mixed sand-mud submarine canyon systems with moderate sand-shale ratios. Additionally, strongly progradational clinoforms partitioned great volumes of sediment into deep-water areas, as reflected by high rates of shelf-edge progradation and apparent toplap. Strongly aggradational clinoforms, in contrast, stored great volumes of sediment on the shelf itself, as indicated by high rates of shelf-edge aggradation and very thick clinoform topsets. G ct and H c therefore increase linearly with sediment volumes partitioned into the shelf, but decrease linearly with sand-and sediment-budget partitioning into deep-water areas, given a constant sediment-supply condition. Growth styles of shelf-margin clinoforms are thus good predictors of source-to-sink sand-and sediment-volume partitioning into and across the shelf, assisting greatly in developing a more dynamic stratigraphy.