Differential Effects of Nitrogen and Phosphorus Fertilization Rates and Fertilizer Placement Methods on P Accumulations in Maize.

Crop production in Afghanistan suffers from limited phosphorus (P) availability, which severely hinders national agriculture sustainability. This study hypothesized that deep fertilizer placement could significantly enhance the uptake of immobile P and, thus, tissue P accumulation and crop yield. A two-year pot experiment growing two maize (Zea mays) hybrid cultivars (Xida-789 and Xida-211) was, therefore, conducted to test these hypotheses under three contrasting fertilizer placement methods (broadcast, side band, and deep band). In doing so, P concentrations in both maize tissues and soils were compared at 45, 60, and 115 days after sowing (DAS) under nine combinations of nitrogen (N) and P fertilizer rates (kg ha-1: N112P45, N112P60, N112P75, N150P45, N150P60, N150P75, N187P45, N187P60, N187P75). Results have shown that deep band placement significantly increased P uptake efficiency, leading to greater P concentration and accumulation in maize tissues compared to the other two fertilization methods. This improved P uptake was attributed to several factors associated with deep placement, including reduced P fixation, enhanced root access to P, and moisture availability for P uptake. Additionally, deep band placement combined with higher N application rates (N187 and N150) further enhanced plant P uptake by promoting P availability and utilization mechanisms. Deep band placement also resulted in significantly higher total soil P, Olsen-P, and P use efficiency than broadcast and side band methods, indicating a more efficient P fertilization strategy for maize that can improve growth and yield. This study also found positive correlations between P concentration in plant organs and soil Olsen-P, highlighting the importance of adequate soil P levels for optimal plant growth. Overall, our results have shown that deep band fertilizer placement emerged as a superior strategy for enhancing P uptake efficiency, utilization, and maize productivity compared to broadcast and side band placement. The outcome generated from the deep band fertilization by this greenhouse study can be recommended for field practices to optimize P fertilizer use and improve maize production while minimizing potential environmental P losses associated with broadcast fertilization.

Variations in Nitrogen Accumulation and Use Efficiency in Maize Differentiate with Nitrogen and Phosphorus Rates and Contrasting Fertilizer Placement Methodologies.

Balanced nitrogen (N) and phosphorus (P) rates, coupled with rational fertilization methodology, could promote crop N accumulation, N use efficiency, and yield production, particularly in semi-arid and arid regions. To test these characteristics, a two-year (2018 and 2019) pot experiment was performed by growing summer maize in a rain-proof glass greenhouse under nine combined N (112, 150, and 187 kg ha-1, urea) and P (45, 60, and 75 kg ha-1 calcium superphosphate) rates and three contrasting fertilizer placements. The fertilizers were placed by broadcast on the soil surface (Broadcast), a side band on a 4 cm strip of soil surface within 7 cm from the sowing line (Side band), and a deep band on a 4 cm strip below 7 cm soil depth within 7 cm from the sowing line (Deep band). Results from three maize growth stages (eight-leaf, 45 days after sowing, DAS; tasseling, 60 DAS; and harvest, 115 DAS) showed that leaf, stem, root N accumulation, and total soil N were significantly increased under Deep band than under both Side band and Broadcast at N150P60, N187P60, N150P75, and N187P75, but not at N112P45, N150P45, N187P45, N112P60, and N112P75. Significantly greater leaf, stem, and root N accumulations were also displayed at N150 and N187 than at N112 for the same P60 or P75 under the Deep band at 60 DAS and 115 DAS; while for leaf and stem, N accumulations were greater at P75 and P60 than at P45 for the same N150 under Deep band at 45 DAS, 60 DAS, and 115 DAS. Significantly greater agronomy N use efficiency, partial factor productivity, and N use efficiency were exhibited under the Deep band than under the Side band and Broadcast at N150P75 and N187P75, but at N150P60 and N187P60 for NUE only. In addition, leaf, stem, seed, and root N concentrations positively correlated with their own N accumulations or soil N concentrations at the tasseling and harvest stages. Our results demonstrate that a synchronized N150P60, N187P60, N150P75, or N187P75 fertilization rate with Deep band placement can improve soil N availability and root N uptake, and thereby, increase aboveground N accumulation, N use efficiency, and yield production of maize, which is particularly practical for small-holder farmers globally.

Integration of metabolome and transcriptome analyses reveals the mechanism of anthocyanin accumulation in purple radish leaves.

Anthocyanins are natural pigments and play significant roles in multiple growth, development, and stress response processes in plants. The vegetables with high anthocyanin content have better colours, higher antioxidant activity than green vegetables and are potent antioxidants with health benefits. However, the mechanism of anthocyanin accumulation in purple and green leaves of Raphanus sativus (radish) is poorly understood and needs further investigation. In the present study, the pigment content in a green leaf cultivar "RA9" and a purple-leaf cultivar "MU17" was characterized and revealed that the MU17 had significantly increased accumulation of anthocyanins and reduced content of chlorophyll and carotenoid compared with that in RA9. Meanwhile, these two cultivars were subjected to a combination of metabolomic and transcriptome studies. A total of 52 massively content-changed metabolites and 3463 differentially expressed genes were discovered in MU17 compared with RA9. In addition, the content of significantly increased flavonoids (such as pelargonidin and cyanidin) was identified in MU17 compared to RA9 using an integrated analysis of metabolic and transcriptome data. Moreover, the quantitative real-time polymerase chain reaction results also confirmed the differences in the expression of genes related to pathways of flavonoids and anthocyanin metabolism in MU17 leaves. The present findings provide valuable information for anthocyanin metabolism and further genetic manipulation of anthocyanin biosynthesis in radish leaves. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01245-w.

Funneliformis mosseae Improves Growth and Nutrient Accumulation in Wheat by Facilitating Soil Nutrient Uptake under Elevated CO2 at Daytime, Not Nighttime.

The concurrent effect of elevated CO2 (eCO2) concentrations and arbuscular mycorrhizal fungi (AMF) on plant growth, carbon (C), nitrogen (N), phosphorus (P) and potassium (K) accumulations in plant and soil is largely unknown. To understand the mechanisms of eCO2 and mycorrhization on wheat (Triticum aestivum) performance and soil fertility, wheat seedlings were grown under four different CO2 environments for 12 weeks, including (1) ambient CO2 (ACO2, 410/460 ppm, daytime/nighttime), (2) sole daytime eCO2 (DeCO2, 550/460 ppm), (3) sole nighttime eCO2 (NeCO2, 410/610 ppm), and (4) dual or continuous daytime/nighttime eCO2 ((D + N)eCO2, 550/610 ppm), and with or without AMF (Funneliformis mosseae) colonization. DeCO2, NeCO2 and (D + N)eCO2 generally significantly increased shoot and root biomass, plant C, N, P and K accumulation, soil invertase and urease activity, but decreased shoot and root N, P and K concentrations, and soil available N, P and K. Compared with non-AMF, AMF effects on above-mentioned characteristics were significantly positive under ACO2, DeCO2 and (D + N)eCO2, but negative on plant biomass, C, N, P and K accumulation under NeCO2. Overall, AMF colonization alleviated soil nutrient constraints on plant responses to DeCO2, while NeCO2 decreased AMF's beneficial effects on plants. These results demonstrated that an integration of AMF's benefits to plants under factual field DeCO2 and/or NeCO2 will be critical for managing the long-term consequence of future CO2 rising on global cropping systems.

Arbuscular Mycorrhization Enhances Nitrogen, Phosphorus and Potassium Accumulation in Vicia faba by Modulating Soil Nutrient Balance under Elevated CO2.

Effects of arbuscular mycorrhizal fungi (AMF), elevated carbon dioxide (eCO2), and their interaction on nutrient accumulation of leguminous plants and soil fertility is unknown. Plant growth, concentrations of tissue nitrogen (N), phosphorus (P), and potassium (K) in 12-week-old nodulated faba bean (Vicia faba, inoculated with Rhizobium leguminosarum bv. NM353), and nutrient use efficiency were thus assessed under ambient CO2 (410/460 ppm, daytime, 07:00 a.m.-19:00 p.m./nighttime, 19:00 p.m.-07:00 a.m.) and eCO2 (550/610 ppm) for 12 weeks with or without AM fungus of Funneliformis mosseae inoculation. eCO2 favored AMF root colonization and nodule biomass production. eCO2 significantly decreased shoot N, P and K concentrations, but generally increased tissue N, P and K accumulation and their use efficiency with an increased biomass production. Meanwhile, eCO2 enhanced C allocation into soil but showed no effects on soil available N, P, and K, while AM symbiosis increased accumulation of C, N, P, and K in both plant and soil though increased soil nutrient uptake under eCO2. Moreover, plant acquisition of soil NO3--N and NH4+-N respond differently to AMF and eCO2 treatments. As a result, the interaction between AM symbiosis and eCO2 did improve plant C accumulation and soil N, P, and K uptake, and an alternative fertilization for legume plantation should be therefore taken under upcoming atmosphere CO2 rising. Future eCO2 studies should employ multiple AMF species, with other beneficial fungal or bacterial species, to test their interactive effects on plant performance and soil nutrient availability in the field, under other global change events including warming and drought.

Daytime, Not Nighttime, Elevated Atmospheric Carbon Dioxide Exposure Improves Plant Growth and Leaf Quality of Mulberry (Morus alba L.) Seedlings.

Almost all elevated atmospheric CO2 concentrations (eCO2) studies have not addressed the potential responses of plant growth to different CO2 in daytime and nighttime. The present study was to determine the impact of daytime and/or nighttime eCO2 on growth and quality of mulberry (Morus alba L.), a perennial multipurpose cash plant. Six-month-old mulberry seedlings were hence grown in environmentally auto-controlled growth chambers under four CO2 concentrations: (1) ambient CO2 (ACO2, 410 µmol mol-1 daytime/460 µmol mol-1 nighttime), (2) sole daytime elevated CO2 (DeCO2, 710 µmol mol-1/460 µmol mol-1), (3) sole nighttime elevated CO2 (NeCO2, 410 µmol mol-1/760 µmol mol-1), and (4) continuous daytime and nighttime elevated CO2 (D + NeCO2, 710 µmol mol-1/760 µmol mol-1). Plant growth characteristics, nutrient uptake, and leaf quality were then examined after 120 days of CO2 exposure. Compared to control, DeCO2 and (D + N)eCO2 increased plant biomass production and thus the harvest of nutrients and accumulation of leaf carbohydrates (starch, soluble sugar, and fatty acid) and N-containing compounds (free amino acid and protein), though there were some decreases in the concentration of leaf N, P, Mg, Fe, and Zn. NeCO2 had no significant effects on leaf yield but an extent positive effect on leaf nutritional quality due to their concentration increase in leaf B, Cu, starch, and soluble sugar. Meanwhile, (D + N)eCO2 decreased mulberry leaf yield and harvest of nutritious compounds for silkworm when compared with DeCO2. The reason may be associated to N, P, Mg, Fe, and Zn that are closely related to leaf pigment and N metabolism. Therefore, the rational application of mineral nutrient (especially N, P, Fe, Mg, and Zn) fertilizers is important for a sustainable mulberry production under future atmosphere CO2 concentrations.

Identification and characterization of BoPUB3: a novel interaction protein with S-locus receptor kinase in Brassica oleracea L.

Armadillo repeat containing 1 (ARC1) is phosphorylated by S-locus receptor kinase (SRK) and functions as a positive regulator in self-incompatibility response of Brassica. However, ARC1 only causes partial breakdown of the self-incompatibility response, and other SRK downstream factors may also participate in the self-incompatibility signaling pathway. In the present study, to search for SRK downstream targets, a plant U-box protein 3 (BoPUB3) was identified from the stigma of Brassica oleracea L. BoPUB3 was highly expressed in the stigma, and its expression was increased with the stigma development and reached to the highest level in the mature-stage stigma. BoPUB3, a 76.8-kDa protein with 697 amino acids, is a member of the PUB-ARM family and contains three domain characteristics of BoARC1, including a U-box N-terminal domain, a U-box motif, and a C-terminal arm repeat domain. The phylogenic tree showed that BoPUB3 was close to BoARC1. The synteny analysis revealed that B. oleracea chromosomal region containing BoPUB3 had high synteny with the Arabidopsis thaliana chromosomal region containing AtPUB3 (At3G54790). In addition, the subcellular localization analysis showed that BoPUB3 primarily localized in the plasma membrane and also in the cytoplasm. The combination of the yeast two-hybrid and in vitro binding assay showed that both BoPUB3 and BoARC1 could interact with SRK kinase domain, and SRK showed much higher level of ß-galactosidase activity in its interaction with BoPUB3 than with BoARC1. These results implied that BoPUB3 is a novel interactor with SRK, which lays a basis for further research on whether PUB3 participates in the self-incompatibility signaling pathway.

Impaired electron transfer accounts for the photosynthesis inhibition in wheat seedlings (Triticum aestivum L.) subjected to ammonium stress.

No single mechanism can provide an adequate explanation for the inhibition of photosynthesis when plants are supplied with ammonium (NH4 + ) as the sole nitrogen (N) source. We performed a hydroponic experiment using two N sources [5 mM NH4 + and 5 mM nitrate (NO3 - )] to investigate the effects of NH4 + stress on the photosynthetic capacities of two wheat cultivars (NH4 + -sensitive AK58 and NH4 + -tolerant XM25). NH4 + significantly inhibited the growth and light-saturated photosynthesis (Asat ) of both cultivars, but the extent of such inhibition was greater in the NH4 + -sensitive AK58. The CO2 concentration did not limit CO2 assimilation under NH4 + nutrition; though both stomatal and mesophyll conductance were significantly suppressed. Carboxylation efficiency (CE), light-saturated potential rate of electron transport (Jmax ), the quantum efficiency of PSII (ΦPSII ), electron transport rate through PSII [Je(PSII)], and Fv /Fm were significantly reduced by NH4 + . As a result, NH4 + nutrition resulted in a significant increase in the production of hydrogen peroxide (H2 O2 ) and superoxide anion radicals (O2 •- ), but these symptoms were less severe in the NH4 + -tolerant XM25, which had a higher capacity of removing elevated reactive oxygen species (ROS). Thus, NH4 + N sources might decreased electron transport efficiency and increased the production of ROS, exacerbating damage to the electron transport chain, leading to a reduced plant photosynthetic capacity.

Dissecting Pistil Responses to Incompatible and Compatible Pollen in Self-Incompatibility Brassica oleracea Using Comparative Proteomics.

Angiosperms have developed self-incompatibility (SI) systems to reject self-pollen, thereby promoting outcrossing. The Brassicaceae belongs to typical sporophytic system, having a single S-locus controlled SI response, and was chosen as a model system to study SI-related intercellular signal transduction. In this regard, the downstream factor of EXO70A1 was unknown. Here, protein two-dimensional electrophoresis (2-DE) method and coupled with matrix-assisted laser desorption ionization/time of flight of flight mass spectrometry (MALDI-TOF -MS) and peptide mass fingerprinting (PMF) was used to further explore the mechanism of SI responses in Brassica oleracea L. var. capitata L. at protein level. To further confirm the time point of protein profile change, total proteins were collected from B. oleracea pistils at 0 min, 1 h, and 2 h after self-pollination. In total 902, 1088 and 1023 protein spots were separated in 0 min, 1 h and 2 h 2-DE maps, respectively. Our analyses of self-pollination profiles indicated that proteins mainly changed at 1 h post-pollination in B. oleracea. Moreover, 1077 protein spots were separated in cross-pollinated 1 h (CP) pistil 2-DE map. MALDI-TOF-MS and PMF successfully identified 34 differentially-expressed proteins (DEPs) in SP and CP 1 h 2-DE maps. Gene ontology and KEGG analysis revealed an array of proteins grouped in the following categories: stress and defense response (35%), protein metabolism (18%), carbohydrate and energy metabolism (12%), regulation of translation (9%), pollen tube development (12%), transport (9%) and cytoskeletal (6%). Sets of DEPs identified specifically in SP or only up-regulated expressed in CP pistils were chosen for funther investigating in floral organs and during the process of self- and cross-pollination. The function of these DEPs in terms of their potential involvement in SI in B. oleracea is discussed.

N-terminal domains of ARC1 are essential for interaction with the N-terminal region of Exo70A1 in transducing self-incompatibility of Brassica oleracea.

Self-incompatibility (SI) is an important mating system to prevent inbreeding and promote outcrossing. ARC1 and Exo70A1 function as the downstream targets of the S-locus receptor kinase and play conservative roles in Brassica SI signaling. Based on the sequence homology, Exo70A1 is divided into four subdomains: leucine zipper (Leu(128)-Leu(149)), hypervariable region (Ser(172)-Leu(197)), SUMO modification motif (Glu(260)-Ile(275)), and pfamExo70 domain (His(271)-Phe(627)). ARC1 contains four domains as follows: leucine zipper (Leu(116)-Leu(137)), coiled-coil domain (Thr(210)-Val(236)), U-box (Asp(282)-Trp(347)) motif, and ARM (Ala(415)-Thr(611)) domain. Bioinformatics analysis, yeast two-hybrid screening and pull-down assays show that leucine zipper and coiled-coil motifs of ARC1116-236 are required for the interaction with Exo70A1, while the addition of ARM motif results in loss of the interaction with Exo70A1. Meanwhile, the N-terminal of Exo70A1 without any domains shows a weak interaction with ARC1, and the level of LacZ expression increases with addition of leucine zipper and reaches the maximum value with hypervariable region and SUMO modification motif, indicating that hypervariable region and SUMO modification motif of Exo70A1172-275 is mainly responsible for the binding with ARC1, whereas pfamExo70 domain has little affinity for ARC1. Lys(181) located in the Exo70A1 hypervariable region may be the ubiquitination site mediating the interaction between ARC1 and Exo70A1. Therefore, both the leucine zipper with coiled-coil structure of ARC1116-236, and the hypervariable region and SUMO modification motif of Exo70A1172-275 are the core interaction domains between ARC1 and Exo70A1. Any factors affecting these core domains would be the regulators of ARC1 mediating ubiquitin degradation in self-incompatible system.

Arbuscular Mycorrhizal Fungus Species Dependency Governs Better Plant Physiological Characteristics and Leaf Quality of Mulberry (Morus alba L.) Seedlings.

Understanding the synergic interactions between arbuscular mycorrhizal fungi (AMF) and its host mulberry (Morus alba L.), an important perennial multipurpose plant, has theoretical and practical significance in mulberry plantation, silkworm cultivation, and relevant textile industry. In a greenhouse study, we compared functional distinctions of three genetically different AMF species (Acaulospora scrobiculata, Funneliformis mosseae, and Rhizophagus intraradices) on physiological and growth characteristics as well as leaf quality of 6-month-old mulberry seedlings. Results showed that mulberry was AMF-species dependent, and AMF colonization significantly increased shoot height and taproot length, stem base and taproot diameter, leaf and fibrous root numbers, and shoot and root biomass production. Meanwhile, leaf chlorophyll a or b and carotenoid concentrations, net photosynthetic rate, transpiration rate and stomatal conductance were generally significantly greater, while intercellular CO2 concentration was significantly lower in AMF-inoculated seedlings than in non-AMF-inoculated counterparts. These trends were also generally true for leaf moisture, total nitrogen, all essential amino acids, histidine, proline, soluble protein, sugar, and fatty acid as they were significantly increased under mycorrhization. Among these three tested AMFs, significantly greater effects of AMF on above-mentioned mulberry physiological and growth characteristics ranked as F. mosseae > A. scrobiculata > R. intraradices, whilst on mulberry leaf quality (e.g., nutraceutical values) for better silkworm growth as F. mosseae ≈A. scrobiculata > R. intraradices. In conclusion, our results showed that greater mulberry biomass production, and nutritional quality varied with AMF species or was AMF-species dependent. Such improvements were mainly attributed to AMF-induced positive alterations of mulberry leaf photosynthetic pigments, net photosynthetic rate, transpiration rate, and N-containing compounds (methionine, threonine, histidine, and proline). As a result, application of Funneliformis mosseae or A. scrobiculata in mulberry plantation could be a promising management strategy to promote silkworm cultivation and relevant textile industry.

Identification of a novel MLPK homologous gene MLPKn1 and its expression analysis in Brassica oleracea.

M locus protein kinase, one of the SRK-interacting proteins, is a necessary positive regulator for the self-incompatibility response in Brassica. In B. rapa, MLPK is expressed as two different transcripts, MLPKf1 and MLPKf2, and either isoform can complement the mlpk/mlpk mutation. The AtAPK1B gene has been considered to be the ortholog of BrMLPK, and AtAPK1B has no role in self-incompatibility (SI) response in A. thaliana SRK-SCR plants. Until now, what causes the MLPK and APK1B function difference during SI response in Brassica and A. thaliana SRKb-SCRb plants has remained unknown. Here, in addition to the reported MLPKf1/2, we identified the new MLPKf1 homologous gene MLPKn1 from B. oleracea. BoMLPKn1 and BoMLPKf1 shared nucleotide sequence identity as high as 84.3 %, and the most striking difference consisted in two fragment insertions in BoMLPKn1. BoMLPKn1 and BoMLPKf1 had a similar gene structure; both their deduced amino acid sequences contained a typical plant myristoylation consensus sequence and a Ser/Thr protein kinase domain. BoMLPKn1 was widely expressed in petal, sepal, anther, stigma and leaf. Genome-wide survey revealed that the B. oleracea genome contained three MLPK homologous genes: BoMLPKf1/2, BoMLPKn1 and Bol008343n. The B. rapa genome also contained three MLPK homologous genes, BrMLPKf1/2, BraMLPKn1 and Bra040929. Phylogenetic analysis revealed that BoMLPKf1/2 and BrMLPKf1/2 were phylogenetically more distant from AtAPK1A than Bol008343n, Bra040929, BraMLPKn1 and BoMLPKn1, Synteny analysis revealed that the B. oleracea chromosomal region containing BoMLPKn1 displayed high synteny with the A. thaliana chromosomal region containing APK1B, whereas the B. rapa chromosomal region containing BraMLPKn1 showed high synteny with the A. thaliana chromosomal region containing APK1B. Together, these results revealed that BoMLPKn1/BraMLPKn1, and not the formerly reported BoMLPKf1/2 (BrMLPKf1/2), was the orthologous genes of AtAPK1B, and no ortholog of BoMLPKf1/2 (BrMLPKf1/2) was found in the A. thaliana genome. We speculated that Brassica MLPKf1/2 might have emerged after speciation of Brassica and A. thailiana, and that it was recruited to the SRK-triggered SI signaling cascade in Brassica.

Sublocalization of Rab23, a mediator of Sonic hedgehog signaling pathway, in hepatocellular carcinoma cell lines.

The novel member of the Rab family of GTPases, Rab23, is an essential negative regulator of the Sonic hedgehog (Shh) signaling pathway. Loss of function mutation of the Rab23 gene causes abnormal development of the neural tube in mice and in certain human congenital diseases. The aberrant overexpression of Rab23 has been associated with various diseases, such as gastric, hepatocellular and lung cancer. The exact function of Rab23 in hepatocellular carcinomas (HCCs), however, remains unknown. Previously, we reported the abnormal sublocalization of Rab23 in lung cancers. In the current study, we investigated the role of Rab23 in HCCs. We report the distinct sublocalization pattern of Rab23 in HCC cell lines. This difference depends on the GDP/GTP-binding form, and inhibition of the Rab23 cycle decreases the expression and nuclear localization of Gli1.