ABSTRACT
This study aims to develop a high-speed and nondestructive mildewed rice grain detection method. First, a set of microscopic images of rice grains contaminated by Aspergillus niger, Penicillium citrinum, and Aspergillus cinerea are acquired to serve as samples, and the mildewed regions are marked. Then, three YOLO-v5 models for identifying regions of rice grain with contamination of Aspergillus niger, Penicillium citrinum, and Aspergillus cinerea in microscopic images are established. Finally, the relationship between the proportion of mildewed regions and the total number of colonies is analyzed. The results show that the proposed YOLO-v5 models achieve accuracy levels of 89.26%, 91.15%, and 90.19% when detecting mildewed regions with contamination of Aspergillus niger, Penicillium citrinum, and Aspergillus cinerea in the microscopic images of the verification set. The proportion of the mildewed region area of rice grain with contamination of Aspergillus niger/Penicillium citrinum/Aspergillus cinerea is logarithmically correlated with the logarithm of the total number of colonies (TVC). The corresponding determination coefficients are 0.7466, 0.7587, and 0.8148, respectively. This study provides a reference for future research on high-speed mildewed rice grain detection methods based on MCV technology.
ABSTRACT
The karst environment is characterized by low soil water content, periodic water deficiency, and poor nutrient availability, which provides an ideal natural laboratory for studying the adaptive evolution of its inhabitants. However, how species adapt to such a special karst environment remains poorly understood. Here, transcriptome sequences of two Urophysa species (Urophysa rockii and Urophysa henryi), which are Chinese endemics with karst-specific distribution, and allied species in Semiaquilegia and Aquilegia (living in non-karst habitat) were collected. Single-copy genes (SCGs) were extracted to perform the phylogenetic analysis using concatenation and coalescent methods. Positively selected genes (PSGs) and clusters of paralogous genes (Mul_genes) were detected and subsequently used to conduct gene function annotation. We filtered 2,271 SCGs and the coalescent analysis revealed that 1,930 SCGs shared the same tree topology, which was consistent with the topology detected from the concatenated tree. Total of 335 PSGs and 243 Mul_genes were detected, and many were enriched in stress and stimulus resistance, transmembrane transport, cellular ion homeostasis, calcium ion transport, calcium signaling regulation, and water retention. Both molecular and morphological evidences indicated that Urophysa species evolved complex strategies for adapting to hostile karst environments. Our findings will contribute to a new understanding of genetic and phenotypic adaptive mechanisms of karst adaptation in plants.
ABSTRACT
The complete mitochondrial genome of Luehdorfia chinensis that is endemic to China is determined. The circular genome is 15 550 bp in length and comprises 13 protein-coding genes (PCGs), 22 tRNAs, two rRNA gene and a control region. Gene order is identical to that of the putative ancestral arrangement of insects. The nucleotide composition of heavy strand is A (40.3%), C (11.2%), T (41.1%) and G (7.3%). All PCGs start with a typical ATN codon except for the gene COI that uses AAC as the start codon. Bayesian analyses support the monophyly of genus Papilio and the sister relationship of Luehdorfia chinensis and L. taibai.
ABSTRACT
This study investigates the influence of climate-induced oscillations and complicated geological conditions on the evolutionary processes responsible for species formation in presently fragmented temperate forest habitats, located in continental East Asia. In addition to this, we also investigate the heavily debated issue of whether temperate forests migrated southwards during such glacial periods or, alternatively, whether there existed refugia within north China, enabling localized survival of temperate forests within this region. In order to achieve these, we surveyed the phylogeography of Bupleurum longiradiatum Turcz. (a herbaceous plant solely confined to temperate forests) constructed from sequence variation in three chloroplast (cp) DNA fragments: trnL-trnF, psbA-trnH and rps16. Our analyses show high genetic diversity within species (h(T)=0.948) and pronounced genetic differentiation among groups (yellow and purple flowers) with a significant phylogeographical pattern (N(ST)>G(ST), P<0.05). Forty-three haplotypes were identified and clustered into two lineages (the purple-flowered lineage and the yellow-flowered lineage). Two corresponding refuge areas, one in Qinling and its adjacent regions and one in the Changbai Mountains/eastern China, were revealed across the entire distribution ranges of Bupleurum longiradiatum. These results provide evidence for the hypothesis that independent refugia were maintained across the range of temperate forests in northern China during the last glacial maximum or earlier cold periods. Bupleurum longiradiatum var. porphyranthum formed a single taxon based on molecular data. This specific formation process suggests that the historical vicariance factors, i.e. climate-induced eco-geographic isolation through the biotic displacement of temperate-deciduous forest habitats, enhanced the divergence of the yellow and purple flower lineages at different spatial-temporal scales and over glacial and interglacial periods. Additionally, geological conditions that restricted gene flow might also be responsible for the observed high genetic and geographic differentiation. A nested clade analysis (NCA) revealed that allopatric fragmentation was a major factor responsible for the phylogeographic pattern observed, and also supported a role for historical vicariance factors. Our results therefore support the inference that Quaternary refugial isolation promoted allopatric speciation of temperate plants in East Asia. This may help to explain the existence of high diversity and endemism of plant species in East Asia.
