ALBERT

Description: 〈span〉Twenty-seven marine and 23 lacustrine clinothem pairs were recognized and analyzed in Qiongdongnan Basin and Pannonian Basin, respectively. A comparison of their architecture highlighted some critical differences in sediment delivery and partitioning between the marine and closed lacustrine basins. In marine Qiongdongnan Basin, rising but forward-moving shelf-edge trajectories and clinoforms with a height of hundreds of meters commonly link downdip to absent or limited sandy bottomsets, whereas the opposite occurs in the lacustrine Pannonian Basin, where very thick bottomsets developed in front of highly aggradational clinoforms. A further comparison of strongly progradational clinothem sets with fairly flat shelf-edge trajectories suggests that relatively thick versus thin or absent sandy bottomsets occur in the marine and lacustrine settings, respectively. The main reason for this marked contrast in sediment partitioning across marine versus lacustrine clinoforms is climate, where a wet-dry climate model needs to be used to explain sediment dispersal to the floor of deep Lake Pannon. During the humid half-cycle, catchment precipitation and sediment flux into Lake Pannon were probably high, and coeval lake-level rise and reduced salinity likely increased shelf accommodation and caused topset aggradation of the forward-moving clinothems. This, in turn, resulted in enhanced hyperpycnal flows and thick bottomsets on the lake-basin floor. During the semiarid half-cycle, lake level was fairly stable, and both the catchment precipitation and sediment flux into Lake Pannon were probably reduced, causing some increase in the salinity, less frequent hyperpycnal flows, and resultant short downlapping clinothems lacking or with only thin bottomsets. Critical differences in sediment delivery and partitioning between marine and lacustrine basins, as highlighted by a comparison of aggradational to progradational clinothem pairs documented herein, draw attention to the pitfall of mechanically applying conventional marine sequence stratigraphy to lacustrine basins.〈/span〉

Description: Lignocellulosic biomass from trees provides a renewable feedstock for biofuels, lumber, pulp, paper, and other uses. Dissecting the mechanism underlying natural variation of the complex traits controlling growth and lignocellulose biosynthesis in trees can enable marker-assisted breeding to improve wood quality and yield. Here, we combined linkage disequilibrium (LD)-based association analysis with traditional linkage analysis to detect the genetic effect of a Populus tomentosa cellulose synthase gene, PtoCesA4 . PtoCesA4 is strongly expressed in developing xylem and leaves. Nucleotide diversity and LD in PtoCesA4 , sampled from the P. tomentosa natural distribution, revealed that PtoCesA4 harbors high single nucleotide polymorphism (SNP) diversity ( T = 0.0080 and w = 0.0098) and low LD ( r 2 ≥ 0.1, within 1400 bp), demonstrating that the potential of a candidate-gene-based LD approach in understanding the molecular basis underlying quantitative variation in this species. By combining single SNP, multi-SNP, and haplotype-based associations in an association population of 460 individuals with single SNP linkage analysis in a family-based linkage populations (1200 individuals), we identified three strong associations (false discovery rate Q 〈 0.05) in both populations. These include two nonsynonymous markers (SNP49 associated with α-cellulose content and SNP59 associated with fiber width) and a noncoding marker (SNP18 associated with α-cellulose content). Variation in RNA transcript abundance among genotypic classes of SNP49 was confirmed in these two populations. Therefore, combining different methods allowed us to examine functional PtoCesA4 allelic variation underlying natural variation in complex quantitative traits related to growth and lignocellulosic biosynthesis.

Description: 〈span〉〈div〉Abstract〈/div〉Twenty-seven marine and 23 lacustrine clinothem pairs were recognized and analyzed in Qiongdongnan Basin and Pannonian Basin, respectively. A comparison of their architecture highlighted some critical differences in sediment delivery and partitioning between the marine and closed lacustrine basins. In marine Qiongdongnan Basin, rising but forward-moving shelf-edge trajectories and clinoforms with a height of hundreds of meters commonly link downdip to absent or limited sandy bottomsets, whereas the opposite occurs in the lacustrine Pannonian Basin, where very thick bottomsets developed in front of highly aggradational clinoforms. A further comparison of strongly progradational clinothem sets with fairly flat shelf-edge trajectories suggests that relatively thick versus thin or absent sandy bottomsets occur in the marine and lacustrine settings, respectively. The main reason for this marked contrast in sediment partitioning across marine versus lacustrine clinoforms is climate, where a wet-dry climate model needs to be used to explain sediment dispersal to the floor of deep Lake Pannon. During the humid half-cycle, catchment precipitation and sediment flux into Lake Pannon were probably high, and coeval lake-level rise and reduced salinity likely increased shelf accommodation and caused topset aggradation of the forward-moving clinothems. This, in turn, resulted in enhanced hyperpycnal flows and thick bottomsets on the lake-basin floor. During the semiarid half-cycle, lake level was fairly stable, and both the catchment precipitation and sediment flux into Lake Pannon were probably reduced, causing some increase in the salinity, less frequent hyperpycnal flows, and resultant short downlapping clinothems lacking or with only thin bottomsets. Critical differences in sediment delivery and partitioning between marine and lacustrine basins, as highlighted by a comparison of aggradational to progradational clinothem pairs documented herein, draw attention to the pitfall of mechanically applying conventional marine sequence stratigraphy to lacustrine basins.〈/span〉