of Botany,Chinese Academy Of Sciences
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Allometry-based estimation of forest aboveground biomass combining LiDAR canopy height attributes and optical spectral indexes
No full textAccurate estimates of forest aboveground biomass (AGB) are essential for global carbon cycle studies and have widely relied on approaches using spectral and structural information of forest canopies extracted from various remote sensing datasets. However, combining the advantages of active and passive data sources to improve estimation accuracy remains challenging. Here, we proposed a new approach for forest AGB modeling based on allometric relationships and using the form of power-law to integrate structural and spectral information. Over 60 km2 of drone light detection and ranging (LiDAR) data and 1,370 field plot measurements, covering the four major forest types of China (coniferous forest, sub-tropical broadleaf forest, coniferous and broadleaf-leaved mixed forest, and tropical broadleaf forest), were collected together with Sentinel-2 images to evaluate the proposed approach. The results show that the most universally useful structural and spectral metrics are the average values of canopy height and spectral index rather than their maximum values. Compared with structural attributes used alone, combining structural and spectral information can improve the estimation accuracy of AGB, increasing R2 by about 10% and reducing the root mean square error by about 22%; the accuracy of the proposed approach can yield a R2 of 0.7 in different forests types. The proposed approach performs the best in coniferous forest, followed by sub-tropical broadleaf forest, coniferous and broadleaf-leaved mixed forest, and then tropical broadleaf forest. Furthermore, the simple linear regression used in the proposed method is less sensitive to sample size and outperforms statistically multivariate machine learning-based regression models such as stepwise multiple regression, artificial neural networks, and Random Forest. The proposed approach may provide an alternative solution to map large-scale forest biomass using space-borne LiDAR and optical images with high accuracy
Global patterns and drivers of soil nematodes in response to nitrogen enrichment
No full textNitrogen (N) deposition significantly lessens ecosystem N limitation, and can even cause N saturation and soil acidification. The effects of N enrichment have been globally assessed for plants, microbial diversity and biomass. However, at higher trophic levels, the global patterns and controlling factors of soil nematodes fed by plants or microbes remain unclear in context of N enrichment. Here, we presented a meta-analysis of 66 N addition experiments on nematode diversity and abundance. Our results revealed a negative dependence of nematode diversity on the N addition rate; however, not for nematode abundance. Across climate gradients, N addition reduced nematode diversity in dry regions but enhanced it in moist regions. Furthermore, N inputs suppressed nematode abundance in cold regions but promoted it in warm regions. Between different trophic levels, the abundance of high trophic-level nematodes (omnivorous-carnivorous) was reduced more than low-level groups (plant-, bacteria-and fungi-feeding nematodes). This occurred through negative N-induced effects, including increased ammonium (NH4+), soil acidification, and reduced microbial biomass. This study indicates that the considerable reduction in nematode communities due to higher N loads in the future will diminish their top down impacts on plant and microbial activities and even simplify soil food web, particularly in cold and dry areas
Linolenic Acid-Derived Oxylipins Inhibit Aflatoxin Biosynthesis in Aspergillus flavus through Activation of Imizoquin Biosynthesis
No full textOxylipins play important signaling roles in aflatoxin (AF) biosynthesis in Aspergillus flavus. We previously showed that exogenous supply of autoxidated linolenic acid (AL) inhibited AF biosynthesis in A. flavus via oxylipins, but the molecular mechanism is still unknown. Here, we performed multiomics analyses of A. flavus grown in media with or without AL. Targeted metabolite analyses and quantitative reverse transcription (qRT)-polymerase chain reaction (PCR) showed that the imizoquin (IMQ) biosynthetic pathway was distinctly upregulated in the presence of AL. C-13-glucose labeling confirmed in parallel that the tricarboxylic acid cycle was also enhanced by AL, consistent with observed increases in mycelial growth. Moreover, we integrated thermal proteome profiling and molecular dynamics simulations to identify a potential receptor of AL; AL was found to interact with a transporter (ImqJ) located in the IMQ gene cluster, primarily through hydrophobic interactions. Further analyses of strains with an IMQ pathway transcription factor overexpressed or knocked out confirmed that this pathway was critical for AL-mediated inhibition of AF biosynthesis. Comparison of 22 assembled A. flavus and Aspergillus oryzae genomes showed that genes involved in the IMQ pathway were positively selected in A. oryzae. Taken together, the results of our study provide novel insights into oxylipin-mediated regulation of AF biosynthesis and suggest potential methods for preventing AF contamination of crops
Loss of innovative traits underlies multiple origins of Aquilegia ecalcarata
No full textTraits are basic attributes of organisms that form the basis for speciation and diversity. The floral nectar spur is a classic example of a key innovative trait. Differences in nectar spur morphology can lead to pollinator specialization and thereby promote reproductive isolation between species. Despite its importance, the nectar spur has been lost in some members of the columbine genus (Aquilegia), resulting in a new spurless trait, and the evolutionary influence of this trait has become a topic of scientific interest. Aquilegia ecalcarata is an important representative columbine species that lacks spurs. Here, we resequenced the genomes of 324 individuals from A. ecalcarata and four related species. We found that A. ecalcarata was divided into three groups based on the phylogenetic relationships and population genetic structures. Topology weighting analysis revealed that A. ecalcarata has multiple origins, and Patterson ' s D statistic showed that the spurless trait may have one origin. Floral morphological analysis revealed significant differences between A. ecalcarata and its spurred sister groups, and the floral phenotypes of the three A. ecalcarata groups have identical or similar floral phenotypes. Our results confirmed that the spurless trait not only produced the phenotype of A. ecalcarata but also contributed to the emergence of the A. rockii phenotype. Moreover, the spurless trait promoted the divergence between A. ecalcarata and its close, spurred relatives. Our research shows that the loss of key innovative traits can play a very important role in speciation and species diversity
Genome-wide investigation and transcriptional profiling of the oxidosqualene cyclase (OSC) genes in wheat (Triticum aestivum)
No full textTriterpene scaffolds are cyclized by differential functional genes of the oxidosqualene cyclase (OSC) gene family, which are widely present in plant species. Thirty-nine OSCs were identified from the hexaploid bread wheat (Triticum aestivum L.) genome. The gene structure organization and the distribution of conserved motifs of OSCs gene family revealed that the TaOSC proteins are highly conserved. By phylogenetic analysis, all OSC proteins from wheat and other cereal crops were clustered into 11 subfamilies (I-XI). Based on the publicly available transcriptional profiling, the tissue-specific expression patterns of TaOSC during several developmental stages revealed diverged expression patterns, indicating that the TaOSC family has undergone subfunctionalization. Furthermore, homeolog expression bias was commonly detected in the TaOSC subfamilies, such as the expression of Ta5A004900 and Ta5D011800 in the subfamily II were specifically expressed in the leaf sheath and flag leaf sheath. In addition, two genes were strongly induced by Pst, indicating that the two homolog genes are involved in the resistance to powdery mildew. Molecular evolution analysis indicated that the TaOSC family genes were undergone purifying selection. So, the powdery mildew response may be very conservative and important biological function of the Ta5A004900 and Ta5D011800 in wheat. In conclusion, these results can be used to explore the diversity of triterpenes and clarify the mechanism of triterpene cyclization, and also provide useful information for future studies on the function of the TaOSC gene family in bread wheat and other important crops
TOR promotes guard cell starch degradation by regulating the activity of β-AMYLASE1 in Arabidopsis
No full textTOR promotes BAM1 expression through BZR1, and induces BAM1 accumulation by inhibiting the autophagy and proteasome pathways, thereby promoting guard cell starch degradation and stomatal opening. Starch is the main energy storage carbohydrate in plants and serves as an essential carbon storage molecule for plant metabolism and growth under changing environmental conditions. The TARGET of RAPAMYCIN (TOR) kinase is an evolutionarily conserved master regulator that integrates energy, nutrient, hormone, and stress signaling to regulate growth in all eukaryotes. Here, we demonstrate that TOR promotes guard cell starch degradation and induces stomatal opening in Arabidopsis thaliana. Starvation caused by plants growing under short photoperiod or low light photon irradiance, as well as inactivation of TOR, impaired guard cell starch degradation and stomatal opening. Sugar and TOR induce the accumulation of beta-AMYLASE1 (BAM1), which is responsible for starch degradation in guard cells. The plant steroid hormone brassinosteroid and transcription factor BRASSINAZOLE-RESISTANT1 play crucial roles in sugar-promoted expression of BAM1. Furthermore, sugar supply induced BAM1 accumulation, but TOR inactivation led to BAM1 degradation, and the effects of TOR inactivation on BAM1 degradation were abolished by the inhibition of autophagy and proteasome pathways or by phospho-mimicking mutation of BAM1 at serine-31. Such regulation of BAM1 activity by sugar-TOR signaling allows carbon availability to regulate guard cell starch metabolism and stomatal movement, ensuring optimal photosynthesis efficiency of plants
Rice CIRCADIAN CLOCK ASSOCIATED 1 transcriptionally regulates ABA signaling to confer multiple abiotic stress tolerance
No full textA rice core circadian clock component confers broad-spectrum tolerance to abiotic stress by transcriptional orchestration of multiple key genes in abscisic acid signaling. The circadian clock facilitates the survival and reproduction of crop plants under harsh environmental conditions such as drought and osmotic and salinity stresses, mainly by reprogramming the endogenous transcriptional landscape. Nevertheless, the genome-wide roles of core clock components in rice (Oryza sativa L.) abiotic stress tolerance are largely uncharacterized. Here, we report that CIRCADIAN CLOCK ASSOCIATED1 (OsCCA1), a vital clock component in rice, is required for tolerance to salinity, osmotic, and drought stresses. DNA affinity purification sequencing coupled with transcriptome analysis identified 692 direct transcriptional target genes of OsCCA1. Among them, the genes involved in abscisic acid (ABA) signaling, including group A protein phosphatase 2C genes and basic region and leucine zipper 46 (OsbZIP46), were substantially enriched. Moreover, OsCCA1 could directly bind the promoters of OsPP108 and OsbZIP46 to activate their expression. Consistently, oscca1 null mutants generated via genome editing displayed enhanced sensitivities to ABA signaling. Together, our findings illustrate that OsCCA1 confers multiple abiotic stress tolerance likely by orchestrating ABA signaling, which links the circadian clock with ABA signaling in rice
Impatiens yunlingensis (Balsaminaceae), a new species from Yunnan, China
No full textImpatiens yunlingensis S.X. Yu, Chang Y. Xia & J.H. Yu (Balsaminaceae), a species new to science dis-covered in Yunnan, China, is described and illustrated here, along with its phylogenetic position among other Impatiens species. Morphological, micro-morphological and molecular evidence is presented as an attestation of its novelty. Impatiens yunlingensis is similar to I. delavayi in having coarsely crenate leave margins, bracts in the upper part, ca. 4/5 length of the pedicels, saccate lower sepal with shallowly bifid spur, linear capsules, and elliptic-oblong, tuberculate seeds, but differs from I. delavayi with lateral sepals 4 (vs. 2), lateral united petal basal lobes subtriangular (vs. dolabriform), and seeds' surface equipped with tubercular ornamentation mostly covered with grain shaped appendages (vs. glabrous and without grain shaped appendages on the top)
A native Trichoderma harzianum strain Th62 displays antagonistic activities against phytopathogenic fungi and promotes the growth of Celosia cristata (vol 62, pg 169, 2021)
No full textNet plant interactions are highly variable and weakly dependent on climate at the global scale
No full textAlthough plant-plant interactions (i.e. competition and facilitation) have long been recognised as key drivers of plant community composition and dynamics, their global patterns and relationships with climate have remained unclear. Here, we assembled a global database of 10,502 pairs of empirical data from the literature to address the patterns of and climatic effects on the net outcome of plant interactions in natural communities. We found that plant interactions varied among plant performance indicators, interaction types and biomes, yet competition occurred more frequently than facilitation in plant communities worldwide. Unexpectedly, plant interactions showed weak latitudinal pattern and were weakly related to climate. Our study provides a global comprehensive overview of plant interactions, highlighting competition as a fundamental mechanism structuring plant communities worldwide. We suggest that further investigations should focus more on local factors (e.g. microclimate, soil and disturbance) than on macroclimate to identify key environmental determinants of interactions in plant communities