【Objective】 Time series of NDVI dataset was used in this study to investigate spatial patterns of cropland phenology in North China region. 【Method】 A smoothing algorithm based on an asymmetric Gaussian function was firstly applied to the NDVI dataset to minimize the effects of anomalous values caused by atmospheric haze and cloud contamination. The cropping system and its related phenology in North China were then estimated based on the smoothed NVDI time-series dataset. 【Result】 The cropping pattern of cropland in North China is mainly characterized by double cropping system and shows a distinct spatial difference, gradually becoming complex as moving toward to the north from the south. Under this cropping system, the starting dates and the ending dates of first growth season in North China vary over space, and regions with double cropping system present a significant advance than those regions with single cropping. On the contrary, the phenology of second growth season including both the starting and the ending dates shows no much difference among regions. 【Conclusion】 Spatial patterns of cropping system and phenology in North China are highly related to its geo-physical environment. In addition, several anthropogenic factors such as crop variety, cultivation levels, irrigation and fertilizers can profoundly influence phenological status. How to discriminate the impacts of biophysical forces and anthropogenic drivers on phenological events of cultivation remains a great challenge for further studies.
Summary 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 c . 2000 species, most of which are shade‐adapted. Here, we present chromosome‐scale genome assemblies for four species of Begonia ( B. loranthoide s, B. masoniana , B. darthvaderiana and B. peltatifolia ), and whole genome shotgun 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 Begonia . Functional enrichment of gene families retained after WGD highlights 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.
Sophora japonica L. (Faboideae, Leguminosae) is an important traditional Chinese herb with a long history of cultivation. Its flower buds and fruits contain abundant flavonoids, and therefore, the plants are cultivated for the industrial extraction of rutin. Here, we determined the complete nucleotide sequence of the mitochondrial genome of S. japonica 'JinhuaiJ2', the most widely planted variety in Guangxi region of China. The total length of the mtDNA sequence is 484,916 bp, with a GC content of 45.4%. Sophora japonica mtDNA harbors 32 known protein-coding genes, 17 tRNA genes, and three rRNA genes with 17 cis-spliced and five trans-spliced introns disrupting eight protein-coding genes. The gene coding and intron regions, and intergenic spacers account for 7.5%, 5.8% and 86.7% of the genome, respectively. The gene profile of S. japonica mitogenome differs from that of the other Faboideae species by only one or two gene gains or losses. Four of the 17 cis-spliced introns showed distinct length variations in the Faboideae, which could be attributed to the homologous recombination of the short repeats measuring a few bases located precisely at the edges of the putative deletions. This reflects the importance of small repeats in the sequence evolution in Faboideae mitogenomes. Repeated sequences of S. japonica mitogenome are mainly composed of small repeats, with only 20 medium-sized repeats, and one large repeat, adding up to 4% of its mitogenome length. Among the 25 pseudogene fragments detected in the intergenic spacer regions, the two largest ones and their corresponding functional gene copies located in two different sets of medium-sized repeats, point to their origins from homologous recombinations. As we further observed the recombined reads associated with the longest repeats of 2,160 bp with the PacBio long read data set of just 15 × in depth, repeat mediated homologous recombinations may play important role in the mitogenomic evolution of S. japonica. Our study provides insightful knowledge to the genetic background of this important herb species and the mitogenomic evolution in the Faboideae species.
Atmospheric nitrogen (N) deposition can profoundly affect methane (CH4) oxidation; however, how it responds to the cessation of N addition has rarely been reported. An incubation experiment was conducted using soils from plots treated with long-term N addition to estimate the soil CH4 oxidation potential. The results showed a unimodal relationship between the levels of soil CH4 consumption and N addition and a slow recovery of CH4 oxidation potential after the cessation of N addition. CH4 consumption was stimulated only at low levels of N addition, and this stimulatory effect quickly diminished with increasing N addition, possibly resulting from the decoupled relationship between the potential for CH4 consumption and the abundance of pmoA-carrying bacteria.
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