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The optimization of phosphate (P) fertilizer application strategies to improve the utilization of P fertilizer in farmlands is urgently required. The objective of this study is to evaluate the effect of P fertilizer application rate and position on maize (Zea mays L.) P utilization. A 2‐year field experiment was conducted with P fertilizer application rate (0, 40, 80, and 120 kg ha−1) and position (5 and 10 cm). Compared with the 5‐cm P position, the 10‐cm P position significantly increased the available phosphorus (AP) content in rhizosphere soil. Surprisingly, the rhizosphere AP content increased or remained the same when the amount of P fertilizer was reduced to 80 kg ha−1 at a distance of 5 cm, compared with that when the amount of P fertilizer was 120 kg ha−1 at a distance of 10 cm. Additionally, there was also an improvement in the root weight, root number, biomass, and maize yield in the 5‐cm position compared to the 10‐cm position. The P fertilizer use efficiency was significantly increased at the 5‐cm position compared to the 10‐cm P position, with increases of 8.93% and 4.11% (P40), 6.38% and 5.10% (P80), and 4.72% and 2.36% (P120) in 2021 and 2022, respectively. Our results showed that a closer position increased the available P content in rhizosphere soil, promoted maize growth, and improved P fertilizer utilization and maize yield, suggesting that the agronomy method with proper location of P increases the soil P availability in rhizosphere soil and P utilization in maize. Core Ideas: P fertilizer application strategies can be improved by altering the phosphate position.Rhizosphere phosphorus content of P80 + 5 cmis greater or equal to P120 + 10 cm.Phosphate fertilizer use efficiency can be improved by 2.3%–8.9% at the 5‐cm position compared to the 10‐cm phosphate position. [ABSTRACT FROM AUTHOR]

Drought stress adversely impacts crop development and yield. Maize frequently encounters drought stress during its life cycle. Improvement of drought tolerance is a priority of maize breeding programs. Here, we identified a novel transcription factor encoding gene, APETALA2 (AP2)/Ethylene response factor (ERF), which is tightly associated with drought tolerance in maize seedlings. ZmERF21 is mainly expressed in the root and leaf and it can be highly induced by polyethylene glycol treatment. Genetic analysis showed that the zmerf21 mutant plants displayed a reduced drought tolerance phenotype, accompanied by phenotypical and physiological changes that are commonly observed in drought conditions. Overexpression of ZmERF21 in maize significantly increased the chlorophyll content and activities of antioxidant enzymes under drought conditions. RNA‐Seq and DNA affinity purification sequencing analysis further revealed that ZmERF21 may directly regulate the expression of genes related to hormone (ethylene, abscisic acid) and Ca signaling as well as other stress‐response genes through binding to the promoters of potential target genes. Our results thereby provided molecular evidence of ZmERF21 is involved in the drought stress response of maize. Summary Statement: Drought stress adversely destroys maize development during the whole life cycle, finally reducing its yield and quality. Thus, improving the performance of maize against drought tolerance is a priority of breeding programs. Here, we identified a novel transcription factor ZmERF21 that is tightly associated with drought tolerance in maize seedlings. ZmERF21 is mainly expressed in root and leaf. Mechanistic analysis demonstrated that ZmERF21 could directly bind to the genes involved in hormone (ethylene, abscisic acid) and Ca signaling pathways. Furthermore, overexpression of ZmERF21 in maize significantly increased drought tolerance, evidenced by chlorophyll content and the activities of antioxidant enzymes. Taken together, our results revealed that ZmERF21 is a positive regulator in response to drought stress in maize. [ABSTRACT FROM AUTHOR]

Abstract Nitric oxide (NO) is an important bioactive molecule that functions in regulating diverse abiotic stresses in plants, whereas its molecular mechanism remains obscure. In this study, treatment with 0.1 mM NO donor (sodium nitroprusside, SNP) significantly alleviated the inhibited growth induced by 15% polyethyleneglycol (PEG)-stimulated water deficiency (WD) for 3 days in maize seedlings, manifested by less decreased plant total fresh weight and dry weight. Comprehensive proteome analysis was further used to measure the expression profiles of leaf proteins of SNP-pretreated maize seedlings under WD conditions to explore the molecular mechanisms of NO-induced WD tolerance. Using 2-DE method, 135 protein spots showed significantly enhanced or reduced abundance, of which 102 spots were successfully identified MALDI-TOF/TOF MS. The identified protein species were associated with diverse functions, and most (52/83, 62.7%) of known protein species were related to photosynthetic processes. Compared to alone PEG treatment, the abundance of 25 identified protein species in SNP + PEG treatment were enhanced among the identified photosynthesis-related protein species. In addition, exogenous SNP application dramatically regulated chlorophyll α fluorescence kinetics e.g. the increase of maximum quantum yield of PSII (F v /F m), photosynthetic performance index (PI), and IP phase, whereas it remarkably reduced the polyphasic OJIP fluorescence transient, the accumulation of reactive oxygen species (H 2 O 2 and O 2 • - ) and malondialdehyde (MDA). These findings suggest that the NO-induced WD tolerance could be associated with improved photosynthetic capability in higher plants. Highlights • mM SNP was the optimum concentration for improving maize growth. • SNP treatment enhances tolerance of maize seedlings to PEG-stimulated water deficiency. • 102 protein species were identified and could be related to NO-induced tolerance. • NO-induced water deficiency tolerance could be associated to photosynthesis. [ABSTRACT FROM AUTHOR]

Transitory starch in cereal plant leaves is synthesized during the day and remobilized at night to provide a carbon source for growth and grain filling, but its mechanistic basis is still poorly understood. The objective of this study is to explore the regulatory mechanism for starch biosynthesis and degradation in plant source organs. Using transmission electron microscopy, we observed that during the day after anthesis, starch granules in mesophyll cells of wheat flag leaves accumulated in chloroplasts and the number of starch granules gradually decreased with wheat leaf growth. During the night, starch granules synthesized in chloroplasts during the day were completely or partially degraded. The transcript levels of 26 starch synthesis-related genes and 16 starch breakdown-related genes were further measured using quantitative real-time reverse transcription polymerase chain reaction. Expression profile analysis revealed that starch metabolism genes were clustered into two groups based on their temporal expression patterns. The genes in the first group were highly expressed and presumed to play crucial roles in starch metabolism. The genes in the other group were not highly expressed in flag leaves and may have minor functions in starch metabolism in leaf tissue. The functions of most of these genes in leaves were further discussed. The starch metabolism-related genes that are predominantly expressed in wheat flag leaves differ from those expressed in wheat grain, indicating that two different pathways for starch metabolism operate in these tissues. This provides specific information on the molecular mechanisms of transitory starch metabolism in higher plants., (© 2014 Scandinavian Plant Physiology Society.)