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Wheat genomic study for genetic improvement of traits in China
No full textBread wheat (Triticum aestivum L.) is a major crop that feeds 40% of the world's population. Over the past several decades, advances in genomics have led to tremendous achievements in understanding the origin and domestication of wheat, and the genetic basis of agronomically important traits, which promote the breeding of elite varieties. In this review, we focus on progress that has been made in genomic research and genetic improvement of traits such as grain yield, end-use traits, flowering regulation, nutrient use efficiency, and biotic and abiotic stress responses, and various breeding strategies that contributed mainly by Chinese scientists. Functional genomic research in wheat is entering a new era with the availability of multiple reference wheat genome assemblies and the development of cutting-edge technologies such as precise genome editing tools, high-throughput phenotyping platforms, sequencing-based cloning strategies, high-efficiency genetic transformation systems, and speed-breeding facilities. These insights will further extend our understanding of the molecular mechanisms and regulatory networks underlying agronomic traits and facilitate the breeding process, ultimately contributing to more sustainable agriculture in China and throughout the world
Effects of mutations of D1-R323, D1-N322, D1-D319, D1-H304 on the functioning of photosystem II in Thermosynechococcus vulcanus
No full textPhotosystem II (PSII) has a number of hydrogen-bonding networks connecting the manganese cluster with the lumenal bulk solution. The structure of PSII from Thermosynechococcus vulcanus (T. vulcanus) showed that D1-R323, D1-N322, D1-D319 and D1-H304 are involved in one of these hydrogen-bonding networks located in the interfaces between the D1, CP43 and PsbV subunits. In order to investigate the functions of these residues in PSII, we generated seven site-directed mutants D1-R323A, D1-R323E, D1-N322R, D1-D319L, D1-D319R, D1-D319Y and D1-H304D of T. vulcanus and examined the effects of these mutations on the growth and functions of the oxygen-evolving complex. The photoautotrophic growth rates of these mutants were similar to that of the wild type, whereas the oxygen-evolving activities of the mutant cells were decreased differently to 63-91% of that of the wild type at pH 6.5. The mutant cells showed a higher relative activity at higher pH region than the wild type cells, suggesting that higher pH facilitated proton egress in the mutants. In addition, oxygen evolution of thylakoid membranes isolated from these mutants showed an apparent decrease compared to that of the cells. This is due to the loss of PsbU during purification of the thylakoid membranes. Moreover, PsbV was also lost in the PSII core complexes purified from the mutants. Taken together, D1-R323, D1-N322, D1-D319 and D1-H304 are vital for the optimal function of oxygen evolution and functional binding of extrinsic proteins to PSII core, and may be involved in the proton egress pathway mediated by Y-Z
CRISPR Cas9-and Cas12a-mediated gusA editing in transgenic blueberry
No full textKey Message A second round of regeneration enriched editing events and enhanced the production of edited blueberry shoots. The new protocol described facilitates high-precision breeding of blueberries using CRISPR Cas technologies. To develop an effective genome editing tool for blueberry breeding, CRISPR-Cas9 and CRISPR-Cas12a were evaluated for their editing efficiencies of a marker gene, beta-glucuronidase (gusA), which was previously introduced into two blueberry cultivars each a single-copy transgene. Four expression vectors were built, with CRISPR-Cas9 and CRISPR-Cas12a each driven by a 35S promoter or AtUbi promoter. Each vector contained two editing sites in the gusA. These four vectors were respectively transformed into the leaf explants of transgenic gusA blueberry and the resulting transgenic calli were induced under hygromycin selection. GUS staining showed that some small proportions of the hygromycin-resistant calli had non-GUS stained sectors, suggesting some possible occurrences of gusA editing. We sequenced GUS amplicons spanning the two editing sites in three blueberry tissues and found about 5.5% amplicons having editing features from the calli transformed with the 35S-Cas9 vector. Further, we conducted a second round of shoot regeneration from leaf explants derived from the initial Cas9- and Cas12a-containing calli (T-0) and analyzed amplicons of the target editing region. Of the newly induced shoots, 15.5% for the 35S-Cas9 and 5.3% for the AtUbi-Cas9 showed non-GUS staining, whereas all of the shoots containing the Cas12a vectors showed blue staining. Sanger sequencing confirmed the editing-induced mutations in two representative non-GUS staining lines. Clearly, the second round of regeneration had enriched editing events and enhanced the production of edited shoots. The results and protocol described will be helpful to facilitating high-precision breeding of blueberries using CRISPR Cas technologies
Leaf structure and photosynthesis in Populus alba under naturally fluctuating environments
No full textThe ability to modulate photosynthesis is essential for plants to adapt to fluctuating growing conditions. Populus species show high tolerance to various and highly variable environments. To understand their response strategies against fluctuating environments, this study investigated the morphological and physiological differences of white poplar (Populus alba) leaves when grown in a phytotron, glasshouse, and field. Our results show that the palisade cells were elongated in the field, which would enhance intercellular CO2 exchange. Photosynthetic capacity was the highest in the field leaves, as shown by higher electron transport rates (1.8 to 6.5 times) and carbon assimilation rates (2.7 to 4.2 times). The decrease of PSI acceptor-side limitation and increase of PSI donor-side limitation suggests changes in PSI redox status may contribute to photoprotection. This plasticity of white poplar allows adjusting its structure and photosynthesis under fluctuating conditions, which may partly enable its outstanding tolerance against environmental changes
Mitreola liuyanii (Loganiaceae), a new species from Guizhou, China
No full textMitreola liuyanii, a new species from Guizhou Province, China, are described and illustrated in this study. Morphologically, it is most similar to M. pingtaoi but can be distinguished from the latter in the characteristics of leaves arranged in a basal rosette or clustered at the stem or branch apex, shorter stem internodes and petioles, smaller narrowly oblanceolate leaf blades with ciliate margin, narrowly lanceolate bracts and glabrous capsules
New insights into the formation of biodiversity hotspots of the Kenyan flora
No full textAim: This study aimed to investigate the distribution patterns of plant diversity in Kenya, how climatic fluctuations and orogeny shaped them, and the formation of its beta-diversity. Location: Kenya, East Africa. Taxon: Angiosperms. Methods: We quantified patterns of turnover and nestedness components of phylogenetic beta-diversity for angiosperm species among neighbouring sites using a well-resolved phylogenetic tree and extensive distribution records from public databases and other published sources. We applied clustering methods to delineate biota based on pairwise similarities among multiple sites and used a random assembly null model to assess the effects of species abundance distribution on phylogenetic beta-diversity. Results: The phylogenetic turnover of the Kenyan flora, intersecting with the biodiversity hotspots Eastern Afromontane, Coastal Forests of Eastern Africa, and Horn of Africa, shows a non-monotonic pattern along a latitudinal gradient that is strongly structured into volcanic and coastal areas. The other areas are mainly dominated by phylogenetic nestedness, even in the eastern part of the equatorial region parallel to the volcanic area. Phylogenetic diversity and phylogenetic structure analyses explain the mechanism of the observed phylogenetic turnover and nestedness patterns. We identified five phytogeographical regions in Kenya: the Mandera, Turkana, Volcanic, Pan Coastal and West Highland Regions. Conclusions: Variations in turnover gradient and coexistence are highly dependent on the regional biogeographical history resulting from climatic fluctuations and longlasting orogeny, which jointly shaped the biodiversity patterns of the Kenyan flora. The nestedness component dominated climatically unstable regions and is presumed to have been caused by heavy local species extinction and recolonization from Volcanic Region. The high turnover component in climatically stable regions may have preserved old lineages and the prevalence of endemic species within narrow ranges
A compiled soil respiration dataset at different time scales for forest ecosystems across China from 2000 to 2018
No full textChina's forests rank fifth in the world by area, covering a broad climatic gradient from cold-temperate to tropical zones, and play a key role in the global carbon cycle. Studies of forest soil respiration (R-s) have increased rapidly in China over the last two decades, but the resulting R-s data need to be summarized. Here, we compile a comprehensive dataset of R-s in China's undisturbed forest ecosystems from the literature published up to 31 December 2018, including monthly R-s and the concurrently measured soil temperature (N=8317), mean monthly R-s (N=5003), and annual R-s (N=634). Detailed plot information was also recorded, such as geographical location, climate factors, stand characteristics, and measurement description. We examine some aspects of the dataset - R-s equations fitted with soil temperature, temperature sensitivity (Q10), monthly variations, and annual effluxes in cold-temperate, temperate, subtropical, and tropical zones. We hope the dataset will be used by the science community to provide a better understanding of the carbon cycle in China's forest ecosystems and reduce uncertainty in evaluating of carbon budget at a large scale. The dataset is publicly available at (Sun et al., 2022)
Carotenoid Single-Molecular Singlet Fission and thePhotoprotection of a Bacteriochlorophyllb-Type Core Light-Harvesting Antenna
No full textCarotenoid (Car) in photosynthesis plays the major roles of accessarylight harvesting and photoprotection, and the underlying structure-functionrelationship attracts continuing research interests. We have attempted to explorethe dynamics of Car triplet excitation (3Car*) in the bacteriochlorophyllb(BChlb)-type light harvesting reaction center complex (LH1-RC) of photosynthetic bacteriumHalorhodospira halochloris. We show that the LH1 antenna binds a single Car that wasidentified as a lycopene derivative. Although the Car is hardly visible in the LH1-RCstationary absorption, it shows up conspicuously in the triplet excitation profile withdistinct vibronic features. This and the ultrafast formation of3Car*on directphotoexcitation of Car unequivocally manifest the unimolecular singletfission reactionof the Car. Moreover, the Car with even one molecule per complex is found to berather effective in quenching3BChlb*. The implications of different3Car*formationmechanisms are discussed, and the self-photoprotection role of BChlbare proposedfor this extremophilic species
Direct and indirect effects of nitrogen enrichment and grazing on grassland productivity through intraspecific trait variability
No full textIn the context of global change, the effects of livestock grazing and nitrogen (N) deposition on ecosystem structure and function of grasslands are not isolated, but simultaneous or even interactive. However, most studies on variations in plant functional traits and linkages to ecosystem function have focused on grazing or N enrichment alone. Few studies have combined these two factors to explore the role of intraspecific trait variability in community assembly and primary productivity, and their pathways on ANPP remain unclear. Here, we examined the effects of N addition and grazing on intra- and interspecific variations in plant functional traits in Inner Mongolia steppe based on two manipulative experiments with six N addition rates or grazing intensities over 6 years. The direct and indirect effects of N addition and grazing on ANPP were further analysed. Our results showed that N enrichment greatly enhanced intraspecific trait variability compared to grazing, which played an important role in maintaining species diversity and primary productivity. There was a negative linear relationship between species richness and intraspecific trait variance within community (T-IP/IC), indicating that N enrichment promoted intraspecific trait variability and increased interspecific niche width, leading to a decrease in species richness. ANPP was positively correlated with T-IP/IC values under N addition or grazing, suggesting that higher intraspecific trait variability was beneficial to maintaining grassland productivity. We also found that N addition had a direct positive effect on ANPP, and intraspecific trait variation was the secondary cause of ANPP variation; in contrast, grazing had an indirect negative effect on ANPP, mainly through species richness and interspecific trait variation. Synthesis and applications. Our findings have important implications for the restoration and management of semi-arid grasslands. Considering the offsetting effects of N addition and grazing on primary productivity, fertilization measures can be integrated into pasture management to quickly restore productivity. In the restoration of degraded grassland by artificial reseeding, the optimal seedling density related to intraspecific variation should be determined, and the forge species should be selected according to plant functional traits, taking into account the strategies of both conservative resource-use and grazing tolerance
Soil Fungi Promote Biodiversity-Productivity Relationships in Experimental Communities of Young Trees
No full textSoil fungi are a major factor maintaining plant diversity and productivity, but the underlying mechanisms are still poorly understood. Based on a biodiversity-ecosystem functioning experiment in southeast China, we evaluated the impacts of root-associated soil fungi on plant total, above- and belowground biomass production in monocultures and in different 2- and 4-tree species mixtures using two pools of four subtropical tree species each. All plots were inoculated with forest soil but half of the plots were additionally treated with fungicide to suppress fungi. Tree species richness promoted individual biomass only in control but not in fungicide-treated soils, leading to positive relative yield totals (RYTs, sum of the relative growth of each tree species in mixture to monoculture) of mixed species plots in control soils. Additive partitioning analysis showed that the net biodiversity effects were due to positive complementarity effects (CE) rather than selection effects. The relative yield of individual tree species was positively correlated with arbuscular mycorrhizal (AM) colonization for AM trees but not significantly correlated with ectomycorrhizal (EM) colonization for EM trees. The molecular analysis of the root-associated fungi showed that larger RYT and CE values were correlated with greater dissimilarity in pathogenic fungal communities between tree species, suggesting distinct pathogen compositions will result in overyielding and high complementarity in mixture