Genomes shed light on the evolution of Begonia, a mega‐diverse genus

Clarifying the evolutionary processes underlying species diversification and adaptation is a key focus of evolutionary biology. Begonia (Begoniaceae) is one of the most species-rich angiosperm genera with ~2,000 species, most of which are shade-adapted. Here, we present chromosome-scale genome assemblies for four species of Begonia (B. loranthoides, B. masoniana, B. darthvaderiana, and B. peltatifolia), and whole genome shot-gun data for an additional 74 Begonia representatives to investigate lineage evolution and shade adaptation of the genus. The four genome assemblies range in size from 331.75 Mb (B. peltatifolia) to 799.83 Mb (B. masoniana), and harbor 22,059 - 23,444 protein-coding genes. Synteny analysis revealed a lineage specific whole-genome duplication (WGD) that occurred just before the diversification of the Begonia. Functional enrichment of gene families retained after WGD highlight the significance of modified carbohydrate metabolism and photosynthesis possibly linked to shade-adaptation in the genus, which is further supported by expansions of gene families involved in light perception and harvesting. Phylogenomic reconstructions and genomics studies indicate that genomic introgression has also played a role in the evolution of Begonia. Overall, this study provides valuable genomic resources for Begonia and suggests potential drivers underlying the diversity and adaptive evolution of this mega-diverse clade

The water lily genome and the early evolution of flowering plants

Water lilies belong to the angiosperm order Nymphaeales. Amborellales, Nymphaeales and Austrobaileyales together form the so-called ANA-grade of angiosperms, which are extant representatives of lineages that diverged the earliest from the lineage leading to the extant mesangiosperms1–3. Here we report the 409-megabase genome sequence of the blue-petal water lily (Nymphaea colorata). Our phylogenomic analyses support Amborellales and Nymphaeales as successive sister lineages to all other extant angiosperms. The N. colorata genome and 19 other water lily transcriptomes reveal a Nymphaealean whole-genome duplication event, which is shared by Nymphaeaceae and possibly Cabombaceae. Among the genes retained from this whole-genome duplication are homologues of genes that regulate flowering transition and flower development. The broad expression of homologues of floral ABCE genes in N. colorata might support a similarly broadly active ancestral ABCE model of floral organ determination in early angiosperms. Water lilies have evolved attractive floral scents and colours, which are features shared with mesangiosperms, and we identified their putative biosynthetic genes in N. colorata. The chemical compounds and biosynthetic genes behind floral scents suggest that they have evolved in parallel to those in mesangiosperms. Because of its unique phylogenetic position, the N. colorata genome sheds light on the early evolution of angiosperms.Supplementary Tables: This file contains Supplementary Tables 1-21.National Natural Science Foundation of China, the open funds of the State Key Laboratory of Crop Genetics and Germplasm Enhancement (ZW201909) and State Key Laboratory of Tree Genetics and Breeding, the Fujian provincial government in China, the European Union Seventh Framework Programme (FP7/2007-2013) under European Research Council Advanced Grant Agreement and the Special Research Fund of Ghent University.http://www.nature.com/naturecommunicationsam2021BiochemistryGeneticsMicrobiology and Plant Patholog

Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species

One major threat to global food security that requires immediate attention, is the increasing incidence of host shift and host expansion in growing number of pathogenic fungi and emergence of new pathogens. The threat is more alarming because, yield quality and quantity improvement efforts are encouraging the cultivation of uniform plants with low genetic diversity that are increasingly susceptible to emerging pathogens. However, the influence of host genome differentiation on pathogen genome differentiation and its contribution to emergence and adaptability is still obscure. Here, we compared genome sequence of 6 isolates of Magnaporthe species obtained from three different host plants. We demonstrated the evolutionary relationship between Magnaporthe species and the influence of host differentiation on pathogens. Phylogenetic analysis showed that evolution of pathogen directly corresponds with host divergence, suggesting that host-pathogen interaction has led to co-evolution. Furthermore, we identified an asymmetric selection pressure on Magnaporthe species. Oryza sativa-infecting isolates showed higher directional selection from host and subsequently tends to lower the genetic diversity in its genome. We concluded that, frequent gene loss or gain, new transposon acquisition and sequence divergence are host adaptability mechanisms for Magnaporthe species, and this coevolution processes is greatly driven by directional selection from host plants

Mean velocity and suspended sediment concentration profile model of turbulent shear flow with probability density function

This work purposes a general mean velocity and a suspended sediment concentration (SSC) model to express distribution at every point of the cross section of turbulent shear flow by using a probability density function method. The probability density function method was used to describe the velocity and concentration profiles interacted on directly by fluid particles in the turbulent shear flow to solve turbulent flow and avoid different dynamical mechanics. The velocity profile model was obtained by solving for the profile integral with the product of the laminar velocity and probability density, through adopting an exponential probability density function to express probability distribution of velocity alteration of a fluid particle in turbulent shear flow. An SSC profile model was also created following a method similar to the above and based on the Schmidt diffusion equation. Different velocity and SSC profiles were created while changing the parameters of the models. The models were verified by comparing the calculated results with traditional models. It was shown that the probability density function model was superior to log-law in predicting stream-wise velocity profiles in coastal currents, and the probability density function SSC profile model was superior to the Rouse equation for predicting average SSC profiles in rivers and estuaries. Outlooks for precision investigation are stated at the end of this article

Measurement of detection distance of laser pointer based on CCD detection technology

In view of the problem of poor stability, low efficiency existed in distance detection method of low power semiconductor laser pointer, a measurement method of detection distance of laser pointer based on CCD detection technology was put forward. The detection distance equation of laser pointer with human eye as the receiver was deduced and modeling by using the CCD sensor and image processing technology. The function mathematical model between the two parameters of optical power and gray scale was also established. The least square method was used to solve correlation coefficient of the equation，the detection distance can be solved by correlation coefficient. The method realizes quantitative detection of detection distance of low power semiconductor laser pointer. The feasibility of the method is verified by experiment

Research on Vibration Behavior of the Plate-Like Joint Interfaces Based on Comprehensive Unit Stiffness Matrix

Abstract: The dynamic characteristics of joint interfaces have significant effect on both static and dynamic behaviors of the whole machine tool structures. Its dynamic model can be simplified as a group of equivalent spring-damping elements, that is, an ‘elastic interlayer ’ without mass. The unit area dynamic characteristic parameters are the key to analyze the dynamic properties of joint interfaces. However, when building the stiffness and damping matrices of the joint interfaces, the interaction between the ‘elastic interlayer ’ and the conjunctions are always ignored, which leads to errors arising. A test system for identifying the unit area dynamic characteristic parameters of different kinds of joint interfaces are represented based on Equivalent Single Degree Of Freedom (ESDOF) system theory. The unit area dynamic characteristic parameters can be applied under all kinds of conditions (including different materials, pre-tightening force, surface roughness, lubricating conditions, media, etc). Then a comprehensive unit stiffness matrix is derived from these parameters. The presented method is compared with the conventional method on analyzing the vibration behavior of an assembled beam structure. The comparison results show that the presented method is in excellent agreement on the actual conditions, which has an obvious advantage on accuracy. The presented method can be used as an effective way for precisely analyzing vibration behavior of complicated mechanical structures with plate-like joint interfaces. Copyright © 2014 IFSA Publishing, S. L