查看更多>>摘要：Summary Gravity is one of the fundamental environmental cues that affect plant development. Indeed, the plant architecture in the shoots and roots is modulated by gravity. Stems grow vertically upward, whereas lateral organs, such as the lateral branches in shoots, tend to grow at a specific angle according to a gravity vector known as the gravitropic setpoint angle (GSA). During this process, gravity is sensed in specialised gravity‐sensing cells named statocytes, which convert gravity information into biochemical signals, leading to asymmetric auxin distribution and driving asymmetric cell division/expansion in the organs to achieve gravitropism. As a hypothetical offset mechanism against gravitropism to determine the GSA, the anti‐gravitropic offset (AGO) has been proposed. According to this concept, the GSA is a balance of two antagonistic growth components, that is gravitropism and the AGO. Although the nature of the AGO has not been clarified, studies have suggested that gravitropism and the AGO share a common gravity‐sensing mechanism in statocytes. This review discusses the molecular mechanisms underlying gravitropism as well as the hypothetical AGO in the control of the GSA.
查看更多>>摘要：Summary Iron (Fe) homeostasis is essential for both plant development and human nutrition. The maintenance of Fe homeostasis involves a complex network in which Fe signaling nodes and circuits coordinate tightly Fe transporters, ferric reductases, H+‐ATPases, low‐molecular‐mass metal chelators, and transporters of chelators and Fe–chelate complexes. Early‐stage studies have revealed different strategies for Fe homeostasis between graminaceous and nongraminaceous plants. Recent progress has refreshed our understanding of previous knowledge, especially on the uptake, phloem transport and systemic signaling of Fe. This review attempts to summarize recent exciting and potentially influential studies on the various routes of Fe uptake and distribution in plants, focusing on breakthroughs that have changed our understanding of plant Fe nutrition.
Yu WangSamantha S. StutzDonald R. OrtRyan A. Boyd...
15页
查看更多>>摘要：Summary Use of a complete dynamic model of NADP‐malic enzyme C4 photosynthesis indicated that, during transitions from dark or shade to high light, induction of the C4 pathway was more rapid than that of C3, resulting in a predicted transient increase in bundle‐sheath CO2 leakiness (?). Previously, ? has been measured at steady state; here we developed a new method, coupling a tunable diode laser absorption spectroscope with a gas‐exchange system to track ? in sorghum and maize through the nonsteady‐state condition of photosynthetic induction. In both species, ? showed a transient increase to >?0.35 before declining to a steady state of 0.2 by 1500?s after illumination. Average ? was 60% higher than at steady state over the first 600?s of induction and 30% higher over the first 1500?s. The transient increase in ?, which was consistent with model prediction, indicated that capacity to assimilate CO2 into the C3 cycle in the bundle sheath failed to keep pace with the rate of dicarboxylate delivery by the C4 cycle. Because nonsteady‐state light conditions are the norm in field canopies, the results suggest that ? in these major crops in the field is significantly higher and energy conversion efficiency lower than previous measured values under steady‐state conditions.
查看更多>>摘要：Summary The lack of field‐based data in the tropics limits our mechanistic understanding of the drivers of net primary productivity (NPP) and allocation. Specifically, the role of local edaphic factors – such as soil parent material and topography controlling soil fertility as well as water and nutrient fluxes – remains unclear and introduces substantial uncertainty in understanding net ecosystem productivity and carbon (C) stocks. Using a combination of vegetation growth monitoring and soil geochemical properties, we found that soil fertility parameters reflecting the local parent material are the main drivers of NPP and C allocation patterns in tropical montane forests, resulting in significant differences in below‐ to aboveground biomass components across geochemical (soil) regions. Topography did not constrain the variability in C allocation and NPP. Soil organic C stocks showed no relation to C input in tropical forests. Instead, plant C input seemingly exceeded the maximum potential of these soils to stabilize C. We conclude that, even after many millennia of weathering and the presence of deeply developed soils, above‐ and belowground C allocation in tropical forests, as well as soil C stocks, vary substantially due to the geochemical properties that soils inherit from parent material.
Ludi WangZongcheng LinJosé CarliAgnieszka Gladala‐Kostarz...
17页
查看更多>>摘要：Summary Self‐incompatibility (SI) involves specific interactions during pollination to reject incompatible (‘self’) pollen, preventing inbreeding in angiosperms. A key event observed in pollen undergoing the Papaver rhoeas SI response is the formation of punctate F‐actin foci. Pollen tube growth is heavily energy‐dependent, yet ATP levels in pollen tubes have not been directly measured during SI. Here we used transgenic Arabidopsis lines expressing the Papaver pollen S‐determinant to investigate a possible link between ATP levels, cytosolic pH ([pH]cyt) and alterations to the actin cytoskeleton. We identify for the first time that SI triggers a rapid and significant ATP depletion in pollen tubes. Artificial depletion of ATP triggered cytosolic acidification and formation of actin aggregates. We also identify in?vivo, evidence for a threshold [pH]cyt of 5.8 for actin foci formation. Imaging revealed that SI stimulates acidic cytosolic patches adjacent to the plasma membrane. In conclusion, this study provides evidence that ATP depletion plays a pivotal role in SI upstream of programmed cell death and reveals a link between the cellular energy status, cytosolic acidification and alterations to the actin cytoskeleton in regulating Papaver SI in pollen tubes.
查看更多>>摘要：Summary Ribosomal RNAs (rRNAs) undergo many modifications during transcription and maturation; homeostasis of rRNA modifications is essential for chloroplast biogenesis in plants. The chloroplast acts as a hub to sense environmental signals, such as cold temperature. However, how RNA modifications contribute to low temperature responses remains unknown. Here we reveal that pseudouridine (Ψ) modification of rice chloroplast rRNAs mediated by the pseudouridine synthase (OsPUS1) contributes to cold tolerance at seedling stage. Loss‐function of OsPUS1 leads to abnormal chloroplast development and albino seedling phenotype at low temperature. We find that OsPUS1 is accumulated upon cold and binds to chloroplast precursor rRNAs (pre‐rRNAs) to catalyse the pseudouridylation on rRNA. These modifications on chloroplast rRNAs could be required for their processing, as the reduction of mature chloroplast rRNAs and accumulation of pre‐rRNAs are observed in ospus1‐1 at low temperature. Therefore, the ribosome activity and translation in chloroplasts is disturbed in ospus1‐1. Furthermore, transcriptome and translatome analysis reveals that OsPUS1 balances growth and stress‐responsive state, preventing excess reactive oxygen species accumulation. Taken together, our findings unveil a crucial function of Ψ in chloroplast ribosome biogenesis and cold tolerance in rice, with potential applications in crop improvement.
NSTL
Wiley