Integrating phosphorus management and cropping technology for sustainable maize production

Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.

Characterization of Bacterial Community Structure and Diversity in Rhizosphere Soils of Three Plants in Rapidly Changing Salt Marshes Using 16S rDNA

在在长江河口的本国的 Phragmites 南极光和 Scirpus mariqueter 和相异的 Spartina alterniflora 的根围土壤的细菌的社区的结构和差异被构造 16S ribosomal 脱氧核糖核酸(rDNA ) 调查克隆图书馆。细菌的差异被把克隆放进运作的分类单位(OTU ) 确定在 】 的顺序类似的水平的组 97% 。398 克隆定序的结果的种系发生的分析在这些工厂的根围土壤显示了细菌的高差异。门 Proteobacteria 的 Alphaproteobacteria， Betaproteobacteria， Gammaproteobacteria，和 Deltaproteobacteria 的成员最充满 rhizobacteria。结合的 Chao 1 非参量的差异评估者 Simpson 的索引(1/D ) 相互被使用定序从每个图书馆获得评估全部的顺序差异和份量上的数据比较优势的水平。结果显示出那 Phragmites， Scirpus，和包含的 Spartina 根围土壤 200， 668，和 382 OTU 分别地。在 Spartina 和 Phragmites 根围土壤的细菌的社区显示了 1/D 揭示的种类优势，而在 Scirpus 根围土壤的细菌的社区有种类丰富的均匀分布。总的来说，从根围土壤的 16S rDNA 克隆图书馆的分析显示在细菌的作文的变化可以在植物群落与种类作文的移动附随地发生。

Intercropping of rice varieties increases the eff iciency of blast control through reduced disease occurrence and variability

Creating a crop-heterogeneous system by intraspecific mixtures of different rice varieties can substantially reduce blast diseases. Such variety mixtures provide an ecological approach for effective disease control, maintaining high yields with the minimum fungicide applications. Whether such an approach is universally applicable for random rice variety combinations and what is the variation pattern of the diseases under intercropping still remains unclear. We conducted two-year large-scale field experiments involving 47 rice varieties/lines and 98 variety-combinations to compare the occurrence of rice blast in monoculture and intercropping plots at multiple sites. In the experiments, the plant height of the selected tradi- tional varieties was about 30 cm taller, and their life cycle was 10 days longer, than that of the improved rice varieties. The monoculture included either traditional or modern rice varieties grown in separate plots. The intercropping included both traditional and modern rice varieties planted together in the same plots. Results from the field experiments under natural disease conditions demonstrated significant reduction for rice blast disease in intercropping plots, compared with that in monoculture plots. For traditional varieties, the average blast incidence reduced from -26% in monoculture to -10% in intercropping, and the disease severity reduced from -17 in monoculture to -5 in intercropping. For modern varieties, the average blast incidence reduced from -19% in monoculture to -10% in intercropping, and the severity from -10 in mono- culture to -4 in intercropping. Traditional rice varieties （-72%） had a much greater increase in the efficiency of disease control than modern varieties （-60%）. In addition, substantially lower values of variance in the blast incidence and severity was detected among the variety combinations in intercropping plots than in monoculture plots. Based on these results, we conclude that the intercropping or mixture of rice varieties greatly reduces the occurrence and variation of rice blast disease in particular variety combinations, which makes the intercropping system more stable and consistent for disease suppression on a large scale of rice cultivation.

Do Higher Resource Capture Ability and Utilization Efficiency Facilitate the Successful Invasion of Exotic Plant? A Case Study of <i>Alternanthera philoxeroides</i>

We tested the hypothesis that introduced populations may have higher resource capture ability and utilization efficiency than native ones of invasive plants. We compared ecophysiological traits including maximum photosynthetic rate (Pmax), apparent quantum yield (Q), specific leaf area (SLA), photosynthetic energy use efficiency (PEUE), photosynthetic nitrogen use efficiency (PNUE), water use efficiency (WUE), mass-based and area-based leaf construction cost (CCmass and CCarea), and mass-based and area-based leaf nitrogen concentration (Nmass and Narea) between native (Argentina) and introduced (USA) populations of two varieties (North Apa and South Apo) of Alternanthera philoxeroides under common garden conditions in China. For Apo and Apa, Pmax, Q, Nmass and WUE were not significantly different between native and introduced populations;introduced populations had significantly lower SLA and lower CCmass but significantly higher Narea and CCarea than native ones. For Apa, the introduced populations showed significantly lower PEUE and lower PNUE while for Apo, PEUE and PNUE were not significantly different between native and introduced populations. The results indicated that introduced populations of A. philoxeroides do not show higher resource capture ability and resource utilization efficiency than their native ones in the common garden experiment, suggesting that these traits may not necessarily contribute to successful invasion of invasive plants.

The impact of urban planning on land use and land cover in Pudong of Shanghai, China

Functional zones in cities constitute the most conspicuous components of newly developed urban areas, and have been a hot spot for domestic and foreign investors in China, which not only show the expanse of urban space accompanied by the shifts both in landscape (from rural to urban) and land use(from less extensive to extensive), but also display the transformation of regional ecological functions. By using the theories and methods of landscape ecology, the structure of landscapes and landscape ecological planning can be analyzed and evaluated for studying the urban functional zones' layout. In 1990, the Central Government of China declared to develop and open up Pudong New Area so as to promote economic development in Shanghai. Benefited from the advantages of Shanghai's location and economy, the government of Pudong New Area has successively built up 7 different functional zones over the past decade according to their functions and strategic goals. Based on the multi-spectral satellite imageries taken in 1990, 1997 and 2000, a landscape ecology analysis was carried out for Pudong New Area of Shanghai, supported by GIS technology. Green space (including croplands) and built-up areas are the major factors considered in developing urban landscape. This paper was mainly concerned with the different spatial patterns and dynamics of green space, built-up areas and new buildings in different functional zones, as influenced by different functional layouts and development strategies. The rapid urbanization in Pudong New Area resulted in a more homogeneous landscape. Agricultural landscape and suburban landscape were gradually replaced by urban landscape as the degree of urbanization increased. As a consequence of urbanization in Pudong, not only built-up patches, but also newly-built patches and green patches merged into one large patch, which should be attributed to the construction policy of extensive green space as the urban development process in Pudong New Area. The shape of green area of 7 functional zones became more and more regular because of the horticultural needs in Shanghai urban planning. Some suggestions were finally made for the study of future urban planning and layout.

CRITICAL EXAMINATION OF WETLANDS ECOSYSTEM SERVICE IN SHANGHAI, CHINA

Wetlands provide many important services to human society, but are at the same time ecologically sensitive and adaptive systems, and are under heavy pressure. As a wetland city, Shanghai city has various types of natural wetlands (chiefly, includes coastal, riverine, lacustrine, and reservoir and pond wetlands), which account for 23.5% of total areas. Meanwhile, Shanghai is a metropolitan city, being confronted with the pressure of port expansion and urban and industrial sprawl, just like the other megalopolises in the world. Based on our earlier study on estimating the ecological service values of wetlands in Shanghai, this paper analyzed the ecological functions of the wetland city, such as nutrient cycling, water regulation and supply, food supply, disturbance control, water treatment, habitats and refugia, aesthetic, education and culture, tidal flats and potential land resources. Unfortunately, the wetland function was being degraded and the ecosystem service was discounted accordingly because of over-reclamation, over-fishing, water pollution, and rapid urbanization in the city. It’s therefore recommended that, to improve the environment of Shanghai ciry, and make the ecosystems sustainable function appropriately, the effective wetland management strategies should be taken.

Rhinogobius immaculatus, a new species of freshwater goby (Teleostei Gobiidae) from the Qiantang River, China

A new freshwater goby, Rhinogobius immaculatus sp. nov., is described here from the Qiantang River in China. It is distinguished from all congeners by the following combination of characters： second dorsal-fin rays I, 7-9; anal-fin rays I, 6-8; pectoral-fin rays 14-15; longitudinal scales 29-31; transverse scales 7-9; predorsal scales 2-5; vertebrae 27 （rarely 28）; preopercular canal absent or with two pores; a red oblique stripe below eye in males; branchiostegal membrane mostly reddish-orange, with 3-6 irregular discrete or connected red blotches on posterior branchiostegal membrane and lower operculum in males; caudal-fin base with a median black spot; and no black blotch on anterior part of first dorsal fin in males.

Seasonal Changes of Energy Fluxes in an Estuarine Wetland of Shanghai,China

The energy budget and regulating factors were investigated over an estuarine wetland during one year of continuous measurement in 2006.The results show that the seasonal changes of the energy fluxes and Bowen ratio(β) were greatly affected by incoming shortwave radiation and canopy growth.During the non-growing season and early-growing season, sensible heat(H) dominated the energy flux, and β could reach a maximum of 2.5, while during most of the growing season, latent heat dominated the energy flux and β fluctuated from 0.4 to 1.0.The energy budget ratio in growing season was about 0.76, and the value would be higher if heat exchange during tidal flooding was in-cluded.During tidal flooding days, β was slightly higher than that at exposure days in most cases.Vegetation cover seems exert little effect on energy partitioning except in March when the standing dead grass intercepted the incoming radiation that might reach the soil surface and reduce the turbulence between soil and atmosphere, thus suppressing the evaporation from the soil though the soil mositure was high at that time.

The impact of geomorphology of marsh creeks on fish assemblage in Changjiang River estuary

Tidal marshes are an important habitat and nursery area for fi sh.In the past few decades,rapid economic development in the coastal areas of China has led to the interruption and destruction of an increasing number of tidal marshes.The growing interest in tidal marsh restoration has increased the need to understand the relationship between geomorphological features and fi sh assemblages in the design of marsh restoration projects.We studied temporal variations in,and the effects of creek geomorphological features on,the estuarine tidal creek fi sh community.Using modifi ed channel nets,we sampled fi sh monthly from March 2007 to February 2008 from seven tidal creeks along an intertidal channel system in Chongming Dongtan National Nature Reserve.Fourteen creek geomorphological variables were measured or derived to characterize intertidal creek geomorphological features.The Gobiidae,with 10 species,was the most speciesrich family.The most abundant fi sh species were Liza affi nis,Chelon haematocheilus,and Lateolabrax maculatus.The fi sh community was dominated by juvenile marine transients,which comprised about 80% of the total catch.The highest abundance of fi sh occurred in June and July,and the highest biomass occurred in December.Canonical redundancy analyses demonstrated that depth,steepness,cross-sectional area,and volume signifi cantly affected the fi sh species assemblage.L.affi nis favored small creeks with high elevations.Synechogobius ommaturus,Acanthogobius luridus,and Carassius auratus preferred deep,steep creeks with a large cross-sectional area and volume.These fi ndings indicate that the geomorphological features of tidal creeks should be considered in the conservation and sustainable management of fi sh species and in the restoration of salt marshes.

Seasonal and population differences in migration of Whimbrels in the East Asian–Australasian Flyway

Background:Conserving migratory birds is challenging due to their reliance on multiple distant sites at different stages of their annual life cycle.The concept of“flyway”,which refers to all areas covered by the breeding,nonbreeding,and migrating of birds,provides a framework for international cooperation for conservation.In the same flyway,however,the migratory activities of the same species can differ substantially between seasons and populations.Clarifying the seasonal and population differences in migration is helpful for understanding migration ecology and for identifying conservation gaps.Methods:Using satellite‑tracking we tracked the migration of Whimbrels(Numenius phaeopus variegatus)from nonbreeding sites at Moreton Bay(MB)and Roebuck Bay(RB)in Australia in the East Asian-Australasian Flyway.Mantel tests were used to analyze the strength of migration connectivity between the nonbreeding and breeding sites of MB and RB populations.Welch’s t test was used to compare the migration activities between the two populations and between northward and southward migration.Results:During northward migration,migration distance and duration were longer for the MB population than for the RB population.The distance and duration of the first leg flight during northward migration were longer for the MB population than for the RB population,suggesting that MB individuals deposited more fuel before departing from nonbreeding sites to support their longer nonstop flight.The RB population exhibited weaker migration connectivity(breeding sites dispersing over a range of 60 longitudes)than the MB population(breeding sites concentrating in a range of 5 longitudes in Far Eastern Russia).Compared with MB population,RB population was more dependent on the stopover sites in the Yellow Sea and the coastal regions in China,where tidal habitat has suffered dramatic loss.However,RB population increased while MB population decreased over the past decades,suggesting that loss of tidal habitat at stopover sites had less impact on the Whimbrel populations,which can use diverse habitat types.Different trends between the populations might be due to the different degrees of hunting pressure in their breeding grounds.Conclusions:This study highlights that conservation measures can be improved by understanding the full annual life cycle of movements of multiple populations of Whimbrels and probably other migratory birds.

Distribution and Selective Effects of Vrn-A1,Vrn-B1,and Vrn-D1 Genes in Derivative Varieties from Four Cornerstone Breeding Parents of Wheat in China

Vernalization, the process of a long exposure to low temperature to induce flowering in plants, is essential for plants to adapt to cold winters. The presence of vernalization genes Vrn-A1, -B1, and -D1 in four cornerstone breeding parents of wheat in China （Funo, Mentana, Yanda 1817, and Bima 4） and 322 derivative varieties （mostly winter wheat） from these parents were determined using PCR based molecular method. The frequencies of the VRN-1 genes in these derivative varieties were in order of Vrn-Dl（67.1%）〉 Vrn-Bl（19.6%）〉 Vrn-Al（5.3%）, which are similar as the former conclusion that Vrn-D1 is associated with the latest heading time, Vrn-A1 the earliest, and Vrn-B1 intermediate values. The frequencies of Vrn-Al and Vrn-B1 loci in the derivative varieties from winter wheat zones were higher than that from spring winter zones. Based on the wheat breeding history in China and the fact of non-random distribution of Vrn-A1 and Vrn-B1 in the derivative varieties from the four parents, there could be a strong selective effect on VRN-1 genes in different regions where the derivative varieties were cultivated.

Springtime migratory restlessness and departure orientation of Great Knots(Calidris tenuirostris)in the south compared to the north Yellow Sea

Background: The motivation of birds to proceed with migration is associated with both endogenous and exogenous factors. According to their migratory situation and to the characteristics of stopover sites, birds might exhibit migratory motivation differently among sites. Although migratory motivation of migrating birds has been well studied in many species, the investigation of the same species in different migratory situations and at different stopover sites is still limited. We predicted that birds at different stopover sites could differ in migratory disposition, including expression of migratory restlessness and responses to environmental cues.Methods: Here we compared migration motivation and orientation of Great Knots(Calidris tenuirostris) at two stopo ver sites, Chongming Dongtan in the south Yellow Sea, which is a temporary rest site, and Yalujiang Estuary Wetland in the north Yellow Sea, which is a critical refuelling site, during northward migration. Modified Emlen funnels, with thermal paper inside to record scratches of the birds, were used to detect activity(intensity and direction) of birds. Environmental conditions, including wind direction and speed, cloud cover, tide condition, times of the day(before and after sunset) were recorded during experiments. Generalized linear models were used to detect the effects of endogenous and exogenous factors on the migratory motivation of the birds.Results: In the south Yellow Sea, the migratory activity intensity of Great Knots was positively related to wind assistance. In the north Yellow Sea, where birds exhibited higher intensity of migratory activity than in the south, the intensity increased and the motivation to initiate migration grew stronger as the season advanced. The Great Knots exhibited wind-related orientation behaviour in the funnels at both sites.Conclusions: The results suggest that the intensity of migratory motivation differed between the two sites. Departure decisions of Great Knots appear to be affected mainly by external factors at the temporary rest site in the south Yellow Sea but possibly by endogenous factors at the final pre-breeding refuelling site in the north Yellow Sea.

Analysis of the Energy Embodied in Foreign Goods Trade of China

In recent years,scientists have been increasingly interested in the energy embodied in traded goods among countries.In this article,the direct energy intensities in various economic sectors of China were calculated with the data of energy consumption and output value of each sector,and the input-output table was used to estimate the external energy consumption.The total energy intensity of all sectors was then obtained.From the data of international trade,the energy embodied in goods trade of China was estimated for the period of 1994-2001.During this period,the average energy intensity of imported goods was always higher than that of exported ones.As a country with a surplus in international goods trade,China actually imported net embodied energy in the past few years.The net embodied energy imported was at the same magnitude of the imported energy in the form of fossil fuels.

Stem and leaf traits as co-determinants of canopy water flux

However,the empirical relationship between leaf stomata anatomy and canopy stomatal conductance(Gs)is surprisingly rare,thereby the underlying biological mechanisms of terrestrial water flux are not well elucidated.To gain further insight into these mechanisms,we reanalyzed the dataset of Gs previously reported by Gao et al.(2015)using a quantile regression model.The results indicated that the reference Cs(Gsref.Gs at 1 kPa)was negatively correlated with wood density at each quantile,which confirmed previous data;however,Gsref was significantly correlated with stomatal density at the 0.6 quantile,i.e.,450 stomata mm-2.This highlighted the potential of using stomatal density as a trait to predict canopy water flux.A conceptual model of co-determinants of xylem and stomatal morphology suggests that these traits and their coordination may play a critical role in determining tree growth,physiological homeostatic response to environmental variables,water use efficiency,and drought resistance.

Effects of Root Extracts from <i>Panax ginseng</i>C. A. Meyer (Araliaceae) of Different Ages on K562 Cells

It is well accepted in China that elder ginsengs have more bioactivity and value than younger ones. However, there is little research about the comparison of beneficial effects of ginsengs with different ages. In this study, ginseng root extracts (GRE) were extracted from ginsengs of 5, 8, 12, 14, and 16 years old, respectively, using 55% ethanol and their effects on human leukemic K562 cells within 48 hours were tested by using Cell Counting Kit-8. The results show that there are significant increases in the cell viability of all the GRE groups compared with Control group within 32 hours. Furthermore, the growth curves of GRE groups were obviously distinct from each other. The cell viability of 5-year-old and 8-year-old GRE groups kept a rapid increase while that of 16-year-old GRE group showed a strong fluctuation within 28 hours. Our results demonstrate that root extracts from ginsengs of different ages contain different bioactivity constituents and have different effects on cell.

Estimation of the Probability of Long-Distance Dispersal: Stratified Diffusion of <i>Spartina alterniflora</i>in the Yangtze River Estuary

The relative contribution of long-distance dispersal and local diffusion in the spread of invasive species has been a subject of much debate. Invasion of the intertidal mudflats by Spartina alterniflora is an ideal example of stratified diffusion, involving both long-distance dispersal of seeds and local diffusion due to clonal growth. In conjunction with experimental data on range radius-versus-time curve, a traveling wave equation-based model is used to investigate the sensitivity of the spread rate of exotic S. alterniflora to parameters of long distance dispersal (c, maximum colonial establishment rate) and local colony diffusion (r, intrinsic growth rate) at two tidal marshes, the Eastern Chongming and the Jiuduansha Islands, at the Yangtze River estuary. Both Eastern Chong ming and Jiuduansha Islands are now national natural reserves in China, which were established in 2005. However, the mudflats and salt marshes in the two reserves are now heavily infested with introduced S. alterniflora, which may threaten the estuarine ecosystems and their biodiversity. S. alterniflora was first found in 1995 on Chongming. For rapid sediment accretion in mudflats in the estuary, S. alterniflora was also intentionally introduced to Jiuduansha in 1997 and Chongming in 2001, which has led to a rapid range expansion in the estuary. Our results show that range expansion of species with stratified diffusion is affected by both long-distance dispersal and local colony diffusion, and that there is a critical c*, below which the spread rate is more influenced by long-distance dispersal than by local diffusion. After applying this model to the invasion of S. alterniflora in the Yangtze River estuary, we derive that c = 1.7 × 10-3, c* = 0.126 and c = 4.8 × 10-3 km-2·yr-1, c* = 0.140 km-2·yr-1 at Chongming and Jiuduansha (Shanghai), respectively. Our results suggest that the range spread of S. alterniflora in the Yangtze River estuary is more influenced by long-distance dispersal than local colony diffusion, and that S. alterniflora generates about 1.7 × 10-3 to 4.8 × 10-3 colonies per square kilometers per year. This study provides important information about dispersal dynamics of S. alterniflora that may be useful for finding optimal control strategies. ·

Migration departure strategies of shorebirds at a final pre-breeding stopover site

Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other life?history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre?breed?ing stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.Methods: We recorded migratory departures of four shorebird species, i.e. Eurasian Curlew(Numenius arquata), Bar?tailed Godwit(Limosa lapponica), Great Knot(Calidris tenuirostris), and Grey Plover(Pluvialis squatarola), at Yaluji?ang Estuary Wetlands in China, a final pre?breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions(rain and ground wind speed and direction) on the departure decision of shorebirds.Results: We found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coast?line and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migra?tory routes. Bar?tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.Conclusions: Body size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tac?tics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre?breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.

Effects of Winter Harvesting and Salinity on the Structure of Regrowing Reed Stands

Harvest and salinity are two important factors of the growth of common reed (Phragmites australis). We here examined the different impact of winter harvest treatment on the Phragmites australis between high and low salinity (mean soil electrical conductivity is 7.87 ms/cm and 0.91 ms/cm) areas in Dongtan wetland of Yangtze River estuary, China. We measured phenology, Shoot density, stem diameter and height, biomass (total, aboveground and belowground biomass) and spike weight. At high salinity areas, harvest significantly inhibited the individual growth of stem height yet enhanced ramet density, and consequently led to an insignificant change in aboveground biomass. The belowground parts of reed were significantly inhibited. The root shoot ratio and the proportion of asexual reproduction decreased significantly. At low salinity areas, however, winter harvest generally has no significant influence on reed growth. Our results suggest that the winter harvest management may cause a decline of reed populations in the long term under condition of high salinity;however winter harvesting can be suggested as a proper management for sustainable utilization of reed communities at low salinity areas.

Transcriptional regulation of bark freezing tolerance in apple(Malus domestica Borkh.)

Freezing tolerance is a significant trait in plants that grow in cold environments and survive through the winter.Apple(Malus domestica Borkh.)is a cold-tolerant fruit tree,and the cold tolerance of its bark is important for its survival at low temperatures.However,little is known about the gene activity related to its freezing tolerance.To better understand the gene expression and regulation properties of freezing tolerance in dormant apple trees,we analyzed the transcriptomic divergences in the bark from 1-year-old branches of two apple cultivars,“Golden Delicious”(G)and“Jinhong”(H),which have different levels of cold resistance,under chilling and freezing treatments.“H”can safely overwinter below−30℃in extremely low-temperature regions,whereas“G”experiences severe freezing damage and death in similar environments.Based on 28 bark transcriptomes(from the epidermis,phloem,and cambium)from 1-year-old branches under seven temperature treatments(from 4 to−29°C),we identified 4173 and 7734 differentially expressed genes(DEGs)in“G”and“H”,respectively,between the chilling and freezing treatments.A gene coexpression network was constructed according to this expression information using weighted gene correlation network analysis(WGCNA),and seven biologically meaningful coexpression modules were identified from the network.The expression profiles of the genes from these modules suggested the gene regulatory pathways that are responsible for the chilling and freezing stress responses of“G”and/or“H.”Module 7 was probably related to freezing acclimation and freezing damage in“H”at the lower temperatures.This module contained more interconnected hub transcription factors(TFs)and cold-responsive genes(CORs).Modules 6 and 7 contained C-repeat binding factor(CBF)TFs,and many CBF-dependent homologs were identified as hub genes.We also found that some hub TFs had higher intramodular connectivity(KME)and gene significance(GS)than CBFs.Specifically,most hub TFs in modules 6 and 7 were activated at the beginning of the early freezing stress phase and maintained upregulated expression during the whole freezing stress period in“G”and“H”.The upregulation of DEGs related to methionine and carbohydrate biosynthetic processes in“H”under more severe freezing stress supported the maintenance of homeostasis in the cellular membrane.This study improves our understanding of the transcriptional regulation patterns underlying freezing tolerance in the bark of apple branches.

Revealing the role of CCoAOMT1: fine-tuning bHLH transcription factors for optimal anther development

The tapetum,a crucial innermost layer encompassing male reproductive cells within the anther wall,plays a pivotal role in normal pollen development.The transcription factors (TFs) bHLH010/089/091 redundantly facilitate the rapid nuclear accumulation of DYSFUNCTIONAL TAPETUM 1,a gatekeeper TF in the tapetum.Nevertheless,the regulatory mechanisms governing the activity of bHLH010/089/091 remain unknown.In this study,we reveal that caffeoyl coenzyme A O-methyltransferase 1 (CCoAOMT1) is a negative regulator affecting the nuclear localization and function of bHLH010 and bHLH089,probably through their K259 site.Our findings underscore that CCoAOMT1 promotes the nuclear export and degradation of bHLH010 and bHLH089.Intriguingly,elevated CCoAOMT1 expression resulted in defective pollen development,mirroring the phenotype observed in bhlh010 bhlh089 mutants.Moreover,our investigation revealed that the K259A mutation in the bHLH089 protein disrupted its translocation from the nucleus to the cytosol and impeded its degradation induced by CCoAOMT1.Importantly,transgenic plants with the probHLH089::bHLH089^(K259A)construct failed to rescue proper pollen development or gene expression in bhlh010 bhlh089 mutants.Collectively,these findings emphasize the need to maintain balanced TF homeostasis for male fertility.They firmly establish CCoAOMT1 as a pivotal regulator that is instrumental in achieving equilibrium between the induction of the tapetum transcriptional network and ensuring appropriate anther development.