Leaf Extension Research Articles

Detection of QTLs controlling flowering in a cross-pollinated F1 population of Miscanthus sinensis

Miscanthus is a perennial rhizomatous grass belonging to Andropogoneae, which is now used as lignocellulosic biomass crop. Miscanthus has a short history of domestication, so further breeding effort for improved biomass production is needed. Flowering plays a critical role in controlling vegetative growth and physiology of plant, so this study focused on finding quantitative trait locus controlling flowering of Miscanthus for use in marker assisted breeding. A cross-pollinated M. sinensis F1 population consisted of 278 progenies was produced, transplanted to the field and assessed in their flowering traits. Julian dates of flag leaf extension, first heading, half heading, first flowering, and half flowering were assessed in 2019, the third year after transplanting when Miscanthus was well established. The average Julian dates of the flowering traits were 198±9, 224±14, 233±14, 239±15 and 253±12, respectively, and showed a proximal normal distribution. Genotype by sequencing conducted by Illumina-hiseq using leaf DNA samples revealed the genetic map consisted of 1988 SNPs with average distance of 1.35 cM. Nine QTLs controlling flowering were detected exceeded 60% of LOD score threshold. These QTLs were neighboring 16 SNP markers, 5 of which were contained in known functional genes including RGL2 (gibberellin pathway regulation). Genetic map and marker information acquired through this study, including either annotated or not annotated markers, are expected to help understand and help breeding new Miscanthus in the future with desired flowering.

Effects of sea cucumber fishing on tropical seagrass productivity

AbstractFishing can drive major ecological change in coastal ecosystems and is typically examined through top‐down trophic impacts. However, the massive removal of biomass can also disrupt key ecological bottom‐up processes, though how these effects shape ecosystems is poorly understood. Here, we examined the ecological roles of two species of commercially exploited sea cucumbers thought to promote primary productivity in nutrient‐poor environments through nutrient provisioning and sediment processing. Using a large‐scale field experiment, we tested whether simulated sea cucumber fishing affected seagrass productivity in a natural system comprising reef and seagrass patches that varied in abundance of vertebrate nutrient providers (i.e., fishes). Our findings were scale‐ and metric‐specific: while we could not detect a change in patch‐level seagrass productivity in response to simulated sea cucumber fishing, individual leaf extension rates were ~15% lower at sites where all sea cucumbers were removed, relative to the highest density, unfished sites. Interestingly, there was no concomitant effect of nutrients from the more abundant reef‐associated fishes, which contribute far more nutrients overall than sea cucumbers. This suggests that sea cucumbers are likely mediating seagrass growth through mechanisms other than direct nutrient provisioning, perhaps through processes associated with sediment processing. Our study demonstrates the potential consequences of under‐regulated and unmonitored sea cucumber fishing on foundation species like seagrasses, while highlighting the importance of taking a community‐based approach to these types of field experiments.

Comparisons of the stomatal conductance and electron transport rate of three Japanese rice cultivars including Himenorin in Ehime Prefecture

This study focused on stomatal conductance (gs) and electron transport rate (ETR) as one possible approach to the mechanisms of controlling canopy temperature and photosynthetic traits in rice. Three Japanese rice cultivars, Koshihikari (KH), Nikomaru (NM), and the new cultivar Himenorin (HR) developed in Ehime Prefecture were selected for the experiment. From the uppermost to the fifth leaves of five or more rice plants of each cultivar, gs and ETR were measured in situ using a handheld porometer/fluorometer. The results revealed the highest gs in HR among the three cultivars in all leaf positions from before the flag leaf extension until the maturity stage, which could be regarded as one of the advantageous mechanisms for moderating the thermal condition of the canopy with larger transpiration and supporting a higher photosynthetic level. The ETR of HR was highest among the three cultivars in most leaf positions from the heading stage to the maturity stage, which could be expected to maintain a higher photosynthetic level. These traits of gs and ETR in HR compared with NM and KH could be assessed as possible synergistic mechanisms for higher production and quality of rice with higher photosynthetic potential.

Pre-harvest Chemical Sprays Extend the Shelf Life and Maintain the Quality of Curry Leaf (Murraya koenigii Sprenge)

Curry leaf being perishable commodity and is mostly subjected to excessive post-harvest losses and quantity deterioration in a short span of time. Pre-harvest management system can minimize the losses of curry leaf and by enhancing the shelf life. Thus the present research was conducted to evaluate the effect of chemical spray on shelf life extension and quality of curry leaf. The experimental treatments were comprised of three chemicals (salicylic acid, sodium carbonate and ascorbic acid) at different concentration and the total number of treatments were ten and replicated thrice following completely randomized design (CRD). The results revealed that pre-harvest application of salicylic acid (SA) @ 100 ppm retains the freshness of curry leaf with extended shelf life without any deterioration in quality. On comparison between treatments, salicylic acid @ 100 ppm delayed physiological loss in weight (25.19%), retained chlorophyll content (1.195 mg/g) and ascorbic acid content (3.510 mg/100g). This was followed by ascorbic acid (AA) @ 100 ppm which prevented the degradation of beta-carotene in curry leaf upto seven days of storage at ambient condition. GC-MS analysis of bioactive compounds extracted from essential oil of curry leaf confirmed the presence of limonene compound in salicylic acid treated sample which is related with extending the shelf life. Hence individual and combined effect of SA @ 100 ppm followed by AA @ 100 ppm considered to be the best pre-harvest treatment for enhancing shelf life and maintaining the quality of curry leaf.

An investigation into the principal modes of action of surfactants and how a novel formulation may improve turfgrass quality by increasing the dominance of Agrostis spp. in golf greens

AbstractThe aim of this study was to establish the mechanisms underpinning the observations made in a field trial that suggested that a novel surfactant treatment could promote bentgrasses (Agrostis spp.) in golf greens that contain annual meadow grass (Poa annua L.). Assessments of the effects of three surfactant treatments (named Treatments 1, 2, and 3) on shoot height, biomass accumulation, rhizosheath properties, soil water distribution, and rooting characteristics were made over the course of two experiments carried out under controlled conditions. We found that the leaf extension rate was significantly affected in the two grass species to different extents, depending on the surfactant used. This finding could have positive implications for turf quality in the field for a newly developed formulation (Treatment 3), which was observed to be the case in the field trial that pre‐dated this study. The same treatment also resulted in significant differences in the grasses in terms of rhizosheath size compared with untreated soil. We found that surfactants affected the distribution of water in the soil by increasing the rhizosheath water content to bulk soil water content ratio, potentially maximizing water and nutrient uptake by the roots. The combination of effects observed with use of the novel surfactant treatment may lead to improved water use efficiency and a more desirable sward composition for golf greens.

Is the Two-Line Hybrid Rice a Hindrance to the Efficient Use of Nitrogen Fertilizer in China?

Two-line hybrid rice (2LH) is accompanied by more nitrogen (N) input. To explore the difference in response of two-line and three-line hybrid rice (3LH) to N application, a three-year split-plot experiment was conducted. Three 2LHs and three 3LHs were set as main plots, and four N rates including 0 kg ha−1 (N0), 90 kg ha−1 (N90), 150 kg ha−1 (N150), and 210 kg ha−1 (N210) were set as subplots. 3LH had more panicles and yielded 7.95%, 6.31%, and 5.48% higher than 2LH in N0, N90, and N150, respectively. 2LH had a greater panicle weight in N210 and yielded 1.45% higher than 3LH. Leaf area index (LAI) had the greatest effect on the yields of both 2LH and 3LH, while the contribution of light extinction coefficient (K) was 46.35% and 12.80% those of LAI, respectively. The LAI, K, and radiation interception rate (RIR) of 2LH were smaller than those of 3LH in N0 and N90. The K of 2LH increased significantly as the N rate increased from 150 kg ha−1 to 210 kg ha−1, while that of 3LH showed no significant change, making the maximum RIR of 2LH greater than that of 3LH. 2LH, which intercepted more radiation through greater leaf extension to achieve higher yields, was able to use nitrogen fertilizer efficiently under a high N rate in China.

Drought-Responsive NAC Transcription Factor RcNAC72 Is Recognized by RcABF4, Interacts with RcDREB2A to Enhance Drought Tolerance in Arabidopsis.

RcNAC72, a key transcription factor that may respond to drought stress in Rosa chinensis ‘Old Blush’, was selected in our previous study. In the present study, we found that RcNAC72 is localized in the nucleus and is a transcriptional activator. RcNAC72 expression could be significantly induced by drought, low temperature, salt as well as abscisic acid (ABA) treatment. Analysis of the promoter revealed that multiple abiotic stress and hormone response elements were located in the promoter region. The promoter could respond to drought, low temperature, salt and ABA treatments to activate GUS gene expression. Overexpressing RcNAC72 in Arabidopsis thaliana enhanced sensitivity to ABA and tolerance to drought stress. Silencing of RcNAC72 by virus-induced gene silencing (VIGS) in rose leaves significantly reduced leaf water loss tolerance and leaf extension capacity. Physical interaction of RcNAC72 with RcDREB2A was shown by means of the yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. RcABF4 was demonstrated to be able to bind to the promoter of RcNAC72 by means of the yeast one-hybrid (Y1H) assay. These results provide new insights into the regulatory network of RcNAC72 response to drought stress in roses.

Molecular mechanism of mulberry response to drought stress revealed by complementary transcriptomic and iTRAQ analyses

BackgroundThe use of mulberry leaves has long been limited to raising silkworms, but with the continuous improvement of mulberry (Morus alba) resource development and utilization, various mulberry leaf extension products have emerged. However, the fresh leaves of mulberry trees have a specific window of time for picking and are susceptible to adverse factors, such as drought stress. Therefore, exploring the molecular mechanism by which mulberry trees resist drought stress and clarifying the regulatory network of the mulberry drought response is the focus of the current work.ResultsIn this study, natural and drought-treated mulberry grafted seedlings were used for transcriptomic and proteomic analyses (CK vs. DS9), aiming to clarify the molecular mechanism of the mulberry drought stress response. Through transcriptome and proteome sequencing, we identified 9889 DEGs and 1893 DEPs enriched in stress-responsive GO functional categories, such as signal transducer activity, antioxidant activity, and transcription regulator activity. KEGG enrichment analysis showed that a large number of codifferentially expressed genes were enriched in flavonoid biosynthesis pathways, hormone signalling pathways, lignin metabolism and other pathways. Through subsequent cooperation analysis, we identified 818 codifferentially expressed genes in the CK vs. DS9 comparison group, including peroxidase (POD), superoxide dismutase (SOD), aldehyde dehydrogenase (ALDHs), glutathione s-transferase (GST) and other genes closely related to the stress response. In addition, we determined that the mulberry gene MaWRKYIII8 (XP_010104968.1) underwent drought- and abscisic acid (ABA)-induced expression, indicating that it may play an important role in the mulberry response to drought stress.ConclusionsOur research shows that mulberry can activate proline and ABA biosynthesis pathways and produce a large amount of proline and ABA, which improves the drought resistance of mulberry. MaWRKYIII8 was up-regulated and induced by drought and exogenous ABA, indicating that MaWRKYIII8 may be involved in the mulberry response to drought stress. These studies will help us to analyse the molecular mechanism underlying mulberry drought tolerance and provide important gene information and a theoretical basis for improving mulberry drought tolerance through molecular breeding in the future.

Lolium perenne engineered for elevated leaf lipids exhibits greater energy density in field canopies under defoliation

Co-expression of diacylglycerol O -acyltransferase (DGAT1) and a lipid droplet-stabilizing protein called Cys-oleosin (collectively ‘HME’ technology) increases foliar lipid concentrations and plant biomass, which could elevate energy yields from perennial ryegrass (PR, Lolium perenne L.)-based pastures. Quantifying the feasible benefits of HME PR necessitates that herbage growth and energy density are quantified on a ground area basis under regular defoliation. We examined the translation, from spaced pots indoors to field canopies (swards), of the fatty acid (FA), gross energy (GE), and biomass enhancing traits associated with HME technology expression in PR. Under controlled indoor conditions in spaced pots, hemizygous HME seedlings with 32% higher leaf FA content (1.2%DW) than null controls exhibited a faster rate of leaf extension. These effects translated into a stable 0.2–0.5 kJ/gDW increase in herbage GE concentration, and a 6–10% herbage growth rate advantage when HME ‘miniswards’ were grown under moderate light competition (LAI 7–9) for five defoliation and regrowth cycles (harvests). However, subsequent growth in a dense canopy (LAI>10) eliminated this HME herbage growth advantage. In two field trials in the Midwest United States, hemizygous HME swards exhibited 25–34% (0.8–1%DW) higher end-of-season herbage FA content than null control swards, and 0.2–0.5 kJ/gDW higher end-of-season herbage GE. Herbage growth rates were generally similar for HME and null control swards across both field seasons. This thorough analysis of trait translation shows that the benefits of enhanced FA and GE translate to HME PR canopies grown in the field. The intrinsic growth advantage of HME PR may be diminished in field canopies such that yield benefits are realized only under limited conditions.

Analyses of the photosynthetic characteristics, chloroplast ultrastructure, and transcriptome of apple (Malus domestica) grown under red and blue lights

BackgroundLight quality significantly affects plant growth and development, photosynthesis, and carbon and nitrogen metabolism. Apple (Malus domestica Borkh.) is a widely cultivated and economically important fruit crop worldwide. However, there are still few studies on the effects of different light qualities on the growth and development of apple seedlings.ResultsIn this study, we explored the effects of blue and red light treatments on the growth and development, photosynthetic characteristics, leaf chloroplast ultrastructure, and carbon and nitrogen metabolism of apple seedlings. Blue light significantly inhibited apple plant growth and leaf extension, but it promoted the development of leaf tissue structures and chloroplasts and positively affected leaf stomatal conductance, the transpiration rate, and photosynthetic efficiency. The red light treatment promoted apple plant growth and root development, but it resulted in loosely organized leaf palisade tissues and low chlorophyll contents. The blue and red light treatments enhanced the accumulation of ammonium nitrogen in apple seedlings. Moreover, the blue light treatment significantly promoted nitrogen metabolism. Additionally, an RNA-seq analysis revealed that both blue light and red light can significantly up-regulate the expression of genes related to carbon and nitrogen metabolism. Blue light can also promote amino acid synthesis and flavonoid metabolism, whereas red light can induce plant hormone signal transduction. The expression of a gene encoding a bHLH transcription factor (MYC2-like) was significantly up-regulated in response to blue light, implying it may be important for blue light-mediated plant development.ConclusionsConsidered together, blue and red light have important effects on apple growth, carbon and nitrogen metabolism. These findings may be useful for determining the ideal light conditions for apple cultivation to maximize fruit yield and quality.

Eliciting effects of magnetized solution on physiological and biochemical characteristics and elemental uptake in hydroponically grown grape (Vitis vinifera L. cv. Thompson Seedless)

Hydroponic systems are used as an instrument to solve a wide range of environmental concerns such as climate change, drought, and soil fertility. Effective growing media are vital to the hydroponically plant cultivation system. Plant reaction to the growing media treated by magnetic fields, as an innovative technology, should be investigated since the magnetic field can constitute a non-toxic and non-residual stimulus. In the current study, some physiological and biochemical responses (leaf fresh and dry weight, biomass, leaf area, plant height, stem diameter, photosynthesis pigments, carbohydrates, protein, and proline contents and peroxidase activity (POD)) and elemental uptake of hydroponically grown grapevines to the magnetic solutions (with 0.1 and 0.2 T intensities) were evaluated. The solutions were magnetized in two ways: 1) solutions magnetized after preparing (S 0.1 and S 0.2), and 2) salts were added to the pre-magnetized waters (W + S 0.1 and W + S 0.2). The results revealed that magnetic treatments had effect on increasing of leaf elements uptake including N+, P+, K+, Ca2+, Fe2+, and Zn2+. Magnetic treatments also stimulated chlorophyll content, leaf extension, leaf fresh and dry weight, and biomass accumulation. Carbohydrates content and POD were promoted in grapes treated by S 0.1 and W + S 0.1 than control. W + S 0.1 and S 0.2 increased the proline and protein content, respectively. The findings proposed that solution magnetization application could act as an elicitor agent to mimic the stress condition, but at the lesser level resulting in activation of grape physiological and biochemical processes and elemental state through stress-related responses.

Growth and flowering responses of eelgrass to simulated grazing and fecal addition by Brant Geese

AbstractSeagrasses provide a wide range of ecosystem services and are prioritized in conservation planning. Management of this dynamic community requires describing seagrass responses to repeated grazing by dependent herbivores. Using two experimental randomized block designs in Humboldt Bay, California, we tested responses of eelgrass (Zostera marina) to separate and combined effects of simulated Brant Goose (Branta bernicla) grazing (clipping to a uniform height) and fecal pellet addition, and then to medium (MED) and severe (SEV) intensities of simulated Brant flock visitation. In Experiment 1, clipping with fecal addition (FC) stimulated more clonal addition of shoots than controls or clipping and fecal addition alone (standardized β = 0.26 relative to control). The FC treatment also had the largest positive, delayed effect (β = 0.135) on density of flowering shoots. In Experiment 2, the MED intensity treatment had positive effects on shoot density (β = 0.149), rates of leaf extension (β = 0.16), and leaf productivity (β = 0.20). These MED treatment responses resulted in the highest measures of above‐ground (β = 0.099) and below‐ground (β = 0.32) biomass. Whole shoot (βMED = 0.33, βSEV = −0.36) and landscape (βMED = 0.34, βSEV = −0.23) levels of productivity for the MED treatment reflected the parabolic shape predicted by the compensatory regrowth hypothesis, likely because light and nutrient resources were available to the eelgrass and meristems that were not damaged. Meristem injury in the SEV treatment likely explained why productivity was low, but the high SEV resource levels allowed these plants to recover to control levels in approximately eight to 10 weeks after the last treatment applications. The MED level of shoot and landscape productivity would optimize low intertidal accessibility for Brant to the most nutritiously valuable leaves. Brant grazing and detrital pathways of carbon flow are likely linked with Brant‐induced productivity contributing to the detrital pathway when Brant are present and after the birds leave the estuary. The effect of Brant grazing on eelgrass sexual reproduction may increase long‐term resilience of estuarine ecosystems.

The effect of autumn closing date on over winter tissue turnover in perennial ryegrass (Lolium perenne L.) swards

AbstractAutumn closing date (CD) in intensive pasture‐based systems influences spring herbage availability. Little is known about the impact of earlier closing of swards in autumn on sward structure. A two‐year experiment was undertaken to investigate the impact of five CD on herbage production, leaf extension rate (LER), leaf senescence rates (LSR), sward free leaf lamina (FLL) content and the production and survival of tillers over winter and into spring. The five CD ranges were October 1–15 (CD1), October 16–30 (CD2), October 31––November 14 (CD3), November 15–29 (CD4), November 30–December 14 (CD5) and sward measurements were made on four measurement dates (MD): December 11 (MD1), January 6 (MD2), January 27 (MD3) and prior to spring defoliation (MD4). Thirty perennial ryegrass tillers were measured until the first defoliation in spring (average 1 March). Herbage mass was greatest in early CD and tillers had greater LER and LSR (4.6 and 4.5 mm tiller−1 day−1 respectively) compared to swards with a later CD (3.2 and 2.3 mm tiller−1 day−1 respectively). Early CD had greater parent and daughter tiller mortality than later CD (parent tiller mortality 1.1 and 0.3 ± 0.19 tillers; daughter tiller mortality 1.1 and 0.3 ± 0.27 tillers respectively). Early CD also had greater LER and LSR in daughter tillers (2.6 and 1.5 mm tiller−1 day−1, respectively) compared to late (1.5 and 0.5 mm tiller−1 day−1, respectively). Earlier closing of sward increased herbage mass in spring, however, there were negative implications, such as increased LSR and tiller mortality.

Two maize cultivars of contrasting leaf size show different leaf elongation rates with identical patterns of extension dynamics and coordination.

Simulating leaf development from initiation to maturity opens new possibilities to model plant–environment interactions and the plasticity of plant architecture. This study analyses the dynamics of leaf production and extension along a maize (Zea mays) shoot to assess important modelling choices. Maize plants from two cultivars originating from the same inbred line, yet differing in the length of mature leaves were used in this study. We characterized the dynamics of the blade and sheath lengths of all phytomers by dissecting plants every 2–3 days. We analysed how differences in leaf size were built up and we examined the coordination between the emergence of organs and phases of their extension. Leaf extension rates were higher in the cultivar with longer leaves than in the cultivar with shorter leaves; no differences were found in other aspects. We found that (i) first post-embryonic leaves were initiated at a markedly higher rate than upper leaves; (ii) below ear position, sheaths were initiated at a time intermediate between tip emergence and appearance, while above the ear position, sheaths were initiated at a high rate, such that the time interval between the blade and sheath initiations decreased for these leaves; and (iii) ear position also marked a change in the correlation in size between successive phytomers with little correlation of size between upper and lower leaves. Our results identified leaf extension rate as the reason for the difference in size between the two cultivars. The two cultivars shared the same pattern for the timing of initiation events, which was more complex than previously thought. The differences described here may explain some inaccuracies reported in functional–structural plant models. We speculate that genotypic variation in behaviour for leaf and sheath initiation exists, which has been little documented in former studies.

Ecological co-benefits from sea cucumber farming: Holothuria scabra increases growth rate of seagrass

Sea cucumber aquaculture is increasing in extent and importance throughout the Indo-Pacific region, supplying a luxury seafood market in Asia. In this context, the grow-out of hatchery-bred juveniles in community-farmed pens is proving to be a viable model, providing increased income security and alternative livelihood options to resource-limited communities. Here, we report a study of the impacts of such sea cucumber farming on the growth of seagrass (a favourable habitat for the animals) at a village-scale aquaculture site in southwest Madagascar. Using experiments, we found that the presence of the hatchery-bred sea cucumberHolothuria scabra(sandfish), at stocking densities of 300 g m-2(similar to the density used in the farmed pens, but relatively high for natural populations), resulted in a large (~30%), statistically significant increase in the leaf extension rate of the locally dominant seagrass speciesThalassia hemprichii. However, the other dominant seagrass species,Cymodocea serrulata, did not significantly change its leaf extension rate in the presence ofH. scabra. Since seagrass is a globally important coastal habitat, supporting high biodiversity, carbon sequestration, shoreline stability and nursery grounds for commercial and small-scale fisheries, the positive effect ofH. scabrafarming on the growth rate of at least one dominant seagrass species implies potential important ecological co-benefits. These co-benefits ofH. scabrafarming are likely to be relevant across the tropical Indo-Pacific coastlines, where this species is cultured.

温度和光周期协同作用对蒙古栎幼苗春季物候的影响

植物物候对气候变化非常敏感，但关于物候对不同气候因子协同作用的响应机制仍不清楚。为此，以蒙古栎为研究对象，针对蒙古栎物候的主要影响因子温度和光周期，利用大型人工气候室，模拟研究了温度与光周期协同作用（对照、增温1.5℃、增温2.0℃，不同光周期（10 h、14 h、18 h）及其协同作用（对照处理、增温1.5℃×18 h、增温1.5℃×10 h、增温2.0℃×18 h、增温2.0℃×10 h））对蒙古栎春季物候的影响与机制。结果表明：（1）相同水分条件下，不同升温程度对蒙古栎幼苗春季物候的影响不同。温升1.5℃促进蒙古栎幼苗春季物候（芽膨大期、芽开放期、展叶始期和展叶盛期）提前；而温升2.0℃则对不同春季物候的影响不同，表现为促进芽休眠解除和芽开放，但抑制叶片展开。（2）相同水分条件下，不同光周期对蒙古栎幼苗不同春季物候的影响存在差异。长光周期对蒙古栎幼苗展叶盛期影响最大，短光周期对芽膨大期影响最大，但均表现为抑制作用。（3）相同水分条件下，温度升高与光周期增加协同作用有助于促进蒙古栎幼苗春季物候提前，但温度升高与光周期缩短协同作用则对春季物候有抑制作用。（4）蒙古栎幼苗春季物候变化与前期气候胁迫程度存在显著正相关，表明前期气候因子也是物候变化的重要影响因子。研究结果丰富了蒙古栎物候响应多气候因子协同作用的认知，有助于促进物候模型的完善。;Plant phenology is very sensitive to climate change. However, the interactive effects of different climatic variables on plant phenology are still unclear. Thus, taking Quercus mongolica as the research object, we studied the interactive effects of different warming and changing photoperiod (control treatment (CK), 1.5℃ warming, 2.0℃ warming; different photoperiods (10 h, 14 h, and 18 h); CK, 1.5℃ warming×18 h, 1.5℃ warming×10 h, 2.0℃ warming×18 h, 2.0℃ warming×10 h) on the spring phenology of Quercus mongolica seedlings based on the experimental data of large artificial climate simulation chamber in the context of global warming. The results are as follows:(1) Under the same water condition, different warming had different effects on the spring phenology of Quercus mongolica seedlings. The 1.5℃ warming promoted the spring phenology, including bud swelling (BS), bud opening (BO), first full leaf (F1), and 50% leaves unfolded (LU) stages. The influence of 2.0℃ warming on different spring phenology was different. 2.0℃ warming promoted the release of bud dormancy and leaf BO, but inhibited the leaf extension. (2) Under the same water condition, the effect of different photoperiods on the spring phenology of Quercus mongolica seedlings was different. The long photoperiod had the greatest influence on the 50% LU stage, while the short photoperiod had the greatest influence on the BS stage, but they all showed negative effects. (3) Under the same water condition, prolonging photoperiod under warming treatments was helpful to promote the spring phenology of Quercus mongolica seedlings, including the BO, F1 and 50% LU stages. While shortening of photoperiod under warming treatments inhibited the spring phenology of Quercus mongolica seedlings, including the BS, F1 and 50% LU stages. (4) There was a significant correlation between spring phenological changes of Quercus mongolica seedlings and previous climate stress, implying that the previous climatic variables should be the significantly controlling factors to phenological changes. The results could enrich the cognition of the interactive effects of multiple climatic variables in Quercus mongolica phenology, and are helpful to promote plant phenology simulation.

Proteomic analysis provides an insight into the molecular mechanism of development and flowering in Lycoris radiata

Lycoris radiata Herb is an important ornamental and medicinal plant native in China. Its productive and reproductive phases are separate. However, the molecular mechanisms governing this unique process of development and flowering are still unclear at the proteome level. In the present study, we used a label-free quantitative proteomic approach to investigate the dynamic changes in the proteome of the bulb tips at six developmental stages in L. radiata, including dormancy (Dor), flowering (Flo), leafing out (LO), rapid leaf extension (RLE), leaf maturity (LMa) and leaf withering (LWi). A total of 2,090 proteins were identified in bulb tips, and each pair of the stages shared 242 (Flo vs. Dor), 82 (LO vs. Flo), 156 (RLE vs. LO), 76 (LMa vs. RLE), 438 (LWi vs. LMa) and 164 (Dor vs. LWi) differentially expressed proteins (DEPs). Analysis of Gene Ontology (GO) and pathway enrichment revealed that the DEPs of Flo vs. Dor were mainly involved in “energy reserve metabolic process”, “cellular polysaccharide metabolic process” and “cellular glucan metabolic process”, whereas the DEPs in LO vs. Flo and RLE vs. LO were mainly involved in “negative regulation of intracellular steroid hormone receptor signaling pathway”. Weighted gene coexpression network analysis showed that there were temperature stimuli, stress responses and immune responses at the dormancy and flowering stages; several proteins, including heat shock protein 83, heat shock cognate 70 kDa protein 2-like isoform X1 and superoxide dismutase [Cu–Zn] 4A, can contribute to these responses. Additionally, 40S ribosomal protein and cell division cycle 5-like protein participated in protein synthesis, cell division and cell expansion during the leaf phase. These results can help us better understand the molecular mechanism of L. radiata development and flowering and provide valuable information about the proteins involved in the development and stress response in other plants of the Lycoris genus.

Exogenous Calcium Alleviates Nocturnal Chilling-Induced Feedback Inhibition of Photosynthesis by Improving Sink Demand in Peanut (Arachis hypogaea).

Arachis hypogaea (peanut) is a globally important oilseed crop with high nutritional value. However, upon exposure to overnight chilling stress, it shows poor growth and seedling necrosis in many cultivation areas worldwide. Calcium (Ca2+) enhances chilling resistance in various plant species. We undertook a pot experiment to investigate the effects of exogenous Ca2+ and a calmodulin (CaM) inhibitor on growth and photosynthetic characteristics of peanut exposed to low night temperature (LNT) stress following warm sunny days. The LNT stress reduced growth, leaf extension, biomass accumulation, gas exchange rates, and photosynthetic electron transport rates. Following LNT stress, we observed larger starch grains and a concomitant increase in nonstructural carbohydrates and hydrogen peroxide (H2O2) concentrations. The LNT stress further induced photoinhibition and caused structural damage to the chloroplast grana. Exogenous Ca2+ enhanced plant growth following LNT stress, possibly by allowing continued export of carbohydrates from leaves. Foliar Ca2+ likely alleviated the nocturnal chilling-dependent feedback limitation on photosynthesis in the daytime by increasing sink demand. The foliar Ca2+ pretreatment protected the photosystems from photoinhibition by facilitating cyclic electron flow (CEF) and decreasing the proton gradient (ΔpH) across thylakoid membranes during LNT stress. Foliar application of a CaM inhibitor increased the negative impact of LNT stress on photosynthetic processes, confirming that Ca2+–CaM played an important role in alleviating photosynthetic inhibition due to the overnight chilling-dependent feedback.

Foliar application of magnesium mitigates soil acidity stress in wheat

AbstractSoil acidity is one of the most important soil constraints for wheat growth, and magnesium (Mg) can play a critical role in mitigating the adverse effects of soil acidity on plants. There is, however, limited information available about the influence of Mg nutrition, especially foliar application, on wheat (Triticum aestivum) growth in acidic soil. In a series of glasshouse experiments, Al‐sensitive wheat genotype (ES8) was grown to vegetative stage (Zadoks 23) with or without foliar Mg application at different rates (0, 50, 200 and 1,000 mg Mg/L), and acidic soil was used as the growth medium with or without lime and Mg amendment. The effects of these treatments on plant growth, physiological responses, tissue concentration of Mg, dry biomass accumulation and root length were characterized. Magnesium application to foliage significantly increased (by around 14%) both shoot and root dry biomass compared to the control (0 foliar Mg). No significant variation was observed in response to different Mg salts (sulphate or chloride) applied to either soil or foliage in relation to wheat growth and physiological responses. Other than liming, foliar Mg application (200 mg Mg/L) coupled with Mg application to soil (20 mg/kg soil) provided optimum conditions for wheat growth in an acid soil. Leaf extension rate, chlorophyll content and root length of wheat treated with 200 mg Mg/L foliar application were increased significantly (by 12%, 10% and 23%, respectively) in comparison to plants treated with 0 foliar Mg. Physiological parameters such as net photosynthetic rate, transpiration rate and stomatal conductance were 4‐fold higher in foliar Mg‐treated plants compared with those receiving no foliar Mg. Therefore, applying 200 mg Mg/L to the foliage may assist in minimizing the negative impact of soil acidity on wheat growth.

R-UNet: Leaf Position Reconstruction in Upstream Radiotherapy Verification

Monolithic active pixel sensor (MAPS) devices are an effective tool for upstream verification of intensity-modulated radiotherapy (IMRT) treatments. It is crucial to measure with high precision the positions of the multi-leaf collimators (MLCs) used to shape the beam in real time, in order to enhance the quality and safety of treatments. This article describes r-UNet, a deep learning-based solution for leaf position reconstruction. The model is used to analyze the high-resolution images produced by a Lassena MAPS device in order to automatically determine the leaf positions. Image segmentation and leaf position estimation are performed simultaneously in a multitask setting. r-UNet obtained an average Dice coefficient of 0.96 ± 0.03 for the reconstructed image masks in the held-out test set; whilst the mean squared error (MSE) resulting from the estimation of the MLC positions is 0.003 mm, with a resolution ranging between 45 and 53 μm for leaf extensions between 1 and 35 mm. On unseen leaf positions, r-UNet yielded a single-leaf resolution between 54 and 88 μm depending on the leaf extension, and an average MSE of 0.07 mm. These results were obtained using single frames of data collected at 34 frames/s.