More N fertilizer, more maize, and less alfalfa: maize benefits from its higher N uptake per unit root length.

Root plasticity is fundamental to soil nutrient acquisition and maximizing production. Different soil nitrogen (N) levels affect root development, aboveground dry matter accumulation, and N uptake. This phenotypic plasticity is well documented for single plants and specific monocultures but is much less understood in intercrops in which species compete for the available nutrients. Consequently, the study tested whether the plasticity of plant roots, biomass and N accumulation under different N levels in maize/alfalfa intercropping systems differs quantitatively. Maize and alfalfa were intercropped for two consecutive years in large soil-filled rhizoboxes and fertilized with 6 different levels of N fertilizer (0, 75, 150, 225, 270, and 300 kg ha-1). Root length, root surface area, specific root length, N uptake and yield were all increased in maize with increasing fertilizer level, whereas higher N rates were supraoptimal. Alfalfa had an optimal N rate of 75-150 kg ha-1, likely because the competition from maize became more severe at higher rates. Maize responded more strongly to the fertilizer treatment in the second year when the alfalfa biomass was much larger. N fertilization contributes more to maize than alfalfa growth via root plasticity responses. Our results suggest that farmers can maximize intercropping yield and economic return by optimizing N fertilizer management.

Plant root plasticity during drought and recovery: What do we know and where to go?

Aims: Drought stress is one of the most limiting factors for agriculture and ecosystem productivity. Climate change exacerbates this threat by inducing increasingly intense and frequent drought events. Root plasticity during both drought and post-drought recovery is regarded as fundamental to understanding plant climate resilience and maximizing production. We mapped the different research areas and trends that focus on the role of roots in plant response to drought and rewatering and asked if important topics were overlooked. Methods: We performed a comprehensive bibliometric analysis based on journal articles indexed in the Web of Science platform from 1900-2022. We evaluated a) research areas and temporal evolution of keyword frequencies, b) temporal evolution and scientific mapping of the outputs over time, c) trends in the research topics analysis, d) marked journals and citation analysis, and e) competitive countries and dominant institutions to understand the temporal trends of root plasticity during both drought and recovery in the past 120 years. Results: Plant physiological factors, especially in the aboveground part (such as "photosynthesis", "gas-exchange", "abscisic-acid") in model plants Arabidopsis, crops such as wheat and maize, and trees were found to be the most popular study areas; they were also combined with other abiotic factors such as salinity, nitrogen, and climate change, while dynamic root growth and root system architecture responses received less attention. Co-occurrence network analysis showed that three clusters were classified for the keywords including 1) photosynthesis response; 2) physiological traits tolerance (e.g. abscisic acid); 3) root hydraulic transport. Thematically, themes evolved from classical agricultural and ecological research via molecular physiology to root plasticity during drought and recovery. The most productive (number of publications) and cited countries and institutions were situated on drylands in the USA, China, and Australia. In the past decades, scientists approached the topic mostly from a soil-plant hydraulic perspective and strongly focused on aboveground physiological regulation, whereas the actual belowground processes seemed to have been the elephant in the room. There is a strong need for better investigation into root and rhizosphere traits during drought and recovery using novel root phenotyping methods and mathematical modeling.

Identification and Functional Characterization of a Low-Density Lipoprotein Receptor Gene Pathogenic Variant in Familial Hypercholesterolemia.

We report a single-point variant of low-density lipoprotein receptor (LDLR) in a Chinese proband with a clinical diagnosis of familial hypercholesterolemia (FH) with a comprehensive functional analysis. Target exome capture-based next-generation sequencing was used for sequencing and identification of genomic variants in the LDLR gene. The expression, cellular location, and function of the mutant LDLR were analyzed. Sequencing of LDLR in FH patients indicated a point variant of single-base substitution (G < A) at a position of 2389 in the 16th exon, which led to a loss of the 16th exon in the LDLR messenger RNA. This genomic variant was found to cause exon 16 deletion in the mutant LDLR protein. Subsequent functional analyses showed that the mutant LDLR was retained in the Golgi apparatus and rarely expressed in the cellular membranes of HepG2 cells. Accordingly, the intake ability of HepG2 cells with the mutant LDLR was significantly reduced (P < 0.05). In conclusion, our results suggest that a mutant with a single-base substitution (c. 2389G > A) in the 16th exon of the LDLR gene was associated with miscleavage of messenger RNA and the retention of mutant LDLR in the Golgi apparatus, which revealed a pathogenic variant in LDLR underlying the pathogenesis of FH.

Motherly care: How Leymus chinensis ramets support their offspring exposed to saline-alkali and clipping stresses.

BACKGROUND: While clonal integration can improve the performance of rhizomatous plants, it remains unclear whether their clonal integration strategy changes under contrasting clipping and saline-alkali homogeneous and heterogeneous environments. Leymus chinensis is a clonal grass native to the Songnen grassland where heavy grazing and patchy saline-alkali stress are serious environmental and ecological problems. We hypothesized that L. chinensis overcomes these stresses through clonal integration, in particular the transfer of nitrogen and carbohydrates. METHODS: A pot experiment was carried out with 15N isotope soil labeling method to study clonal integration strategy in the connected mother and daughter ramets of L. chinensis. The connected ramet pairs were grown in homogeneous (both connected ramets were treated) and heterogeneous (only daughter ramets were treated) environments with four treatments: control, clipping (60% aboveground biomass removal), saline-alkali (3.45 g of NaCl, NaHCO3, and Na2CO3 per pot), and clipping × saline-alkali. RESULTS: A significant amount (22.5%) of 15N was transferred from mother to daughter ramets under non-stressed conditions. When homogeneously stressing both mother and daughter ramets, N transfer was significantly reduced to 8.5--14.6%, independent of the nature of the stress. When only daughters were stressed (heterogeneous stress), saline-alkali stress led to a division of labor where daughters had enhanced photosynthesis, and mother ramets had increased 15N uptake and growth. Clipping only daughters reduced biomass and 15N uptake of both daughter and mother ramets. CONCLUSIONS: Our results demonstrated that clonal integration also occurs in homogeneous favorable environments but is reduced under homogeneous stress. In heterogeneous environments, clonal integration is used to translocate resource after clipping and a division of labor is established to overcome saline-alkali stress. Clonal integration continued even when daughters were severely stressed by the combined treatments. Our findings suggest that these mechanisms are key to the success of L. chinensis in the Songnen grassland.

Quantitative metabolome and transcriptome analysis reveals complex regulatory pathway underlying photoinduced fiber color formation in cotton.

As an important plant single cell model and textile application materials, poorly known about fiber color formation in cotton, which is sensitively regulated by environmental signals. Our studies underline the importance of photo signal on sensitive fiber color formation and characterize fiber color early initiation (15 DPA) and late accumulated metabolites (45 DPA) in different lighting condition. The results revealed 236 differential metabolites between control and shading, of which phenylpropanoids metabolites accounted for 20%, including uncharacterized novel metabolites and pathways. Furthermore, the early initiation specific genes respond to the absence of light are highly correlated with phenylpropanoid metabolites related to pigmentation. The current study reveals the complex pathways involving early initiation regulation and late metabolic pathways. In addition, the collection composed of uncharacterized photoinduced metabolites and early initiation signaling/regulatory genes were identified, which are important resources for understanding fiber color formation. This report provides new insight into molecular regulatory and biochemical basis underlying photoinduced fiber color formation in cotton.

Ectopic Expressions of the GhLETM1 Gene Reveal Sensitive Dose Effects on Precise Stamen Development and Male Fertility in Cotton.

The homologous leucine zipper/EF-hand-containing transmembranes (LETMs) are highly conserved across a broad range of eukaryotic organisms. The LETM functional characteristics involved in biological process have been identified primarily in animals, but little is known about the LETM biological function mode in plants. Based on the results of the current investigation, the GhLETM1 gene crucially affects filament elongation and anther dehiscence of the stamen in cotton. Both excessive and lower expression of the GhLETM1 gene lead to defective stamen development, resulting in shortened filaments and indehiscent anthers with pollen abortion. The results also showed that the phenotype of the shortened filaments was negatively correlated with anther defects in the seesaw model under the ectopic expression of GhLETM1. Moreover, our results notably indicated that the gene requires accurate expression and exhibits a sensitive dose effect for its proper function. This report has important fundamental and practical significance in crop science, and has crucial prospects for genetic engineering of new cytoplasmic male sterility lines and breeding of crop hybrid varieties.

Lead Tolerance and Enrichment Characteristics of Several Ornamentals Under Hydroponic Culture.

The growth response, tolerance, and enrichment characteristics of six ornamental species, Chlorophytum comosum, Calendula officinalis, Iris lacteal, Belamcanda chinensis, Saponaria officinalis, and Polygonum lapathifolium were studied under hydroponic culture with lead (Pb) concentrations ranging from 0 to 1000 mg/L. The results showed that the growth of the tested ornamental species under Pb stress was inhibited. Belamcanda chinensis presented the largest tolerance index (0.75), and Calendula officinalis had the highest toxicity threshold (500 mg/L) under Pb stress. The highest Pb contents in the shoots were detected in Iris lacteal and Belamcanda chinensis. The enrichment coefficients in the shoots of Iris lacteal and Belamcanda chinensis were significantly higher than those in the other ornamental species. In conclusion, Iris lacteal and Belamcanda chinensis are the most tolerant and have the greatest Pb enrichment and translocation abilities under Pb stress, and thus, they have a strong potential to restore Pb-contaminated water bodies and soils.