Increasing Plant Size Research Articles

Endophyte Community Changes in the Seeds of Eight Plant Species following Inoculation with a Multi-Endophytic Bacterial Consortium and an Individual Sphingomonas wittichii Strain Obtained from Noccaea caerulescens.

Noccaea caerulescens, a hyperaccumulator plant species known for its metal tolerance and accumulation abilities, harbours a microbiome of interest within its seed. These seed-associated bacteria, often referred to as seed endophytes, play a unique role in seed germination and plant growth and health. This work aimed to address how inoculating seeds of eight different plant species-Medicago sativa (alfalfa), Zea mays (corn), Raphanus sativus (radish), Helianthus annus (sunflower), Cucurbita pepo subsp. pepo (squash), Beta vulgaris subsp. cicla (rainbow chard), Arabidopsis thaliana (thale cress), and Noccaea caerulescens (penny cress)-with a bacterial consortium made from the seed endophytes of N. caerulescens would affect the seed microbiome of each test plant species, as well as inoculation with a strain of the bacterium Sphingomonas wittichii, which was previously isolated from seeds of N. caerulescens. Additionally, we aimed to offer preliminary plant tests in order to determine the best seed treatment plan for future research. The results showed that inoculation with the bacterial consortium held the most potential for increasing plant size (p < 0.001) and increasing germination rate (p < 0.05). The plant that responded best to inoculation was N. caerulescens (penny cress), likely because the microbes being introduced into the seed were not foreign. This paper also offers the first insight into the seed endophytes of Beta vulgaris subsp. cicla, highlighting an abundance of Proteobacteria, Firmicutes, and Actinobacteriota.

Expression of the plastocyanin gene PETE2 in Camelina sativa improves seed yield and salt tolerance

Plastocyanin functions as an electron carrier in the photosynthetic electron transport chain, located at the thylakoid membrane. In several species, endogenous plastocyanin levels are correlated with the photosynthetic electron transport rate. Overexpression of plastocyanin genes in Arabidopsis thaliana increases plant size, but this phenomenon has not been observed in crop species. Here, we investigated the effects of heterologous expression of a gene encoding a plastocyanin isoform from Arabidopsis, AtPETE2, in the oil seed crop Camelina sativa under standard growth conditions and under salt stress. AtPETE2 heterologous expression enhanced photosynthetic activity in Camelina, accelerating plant development and improving seed yield under standard growth conditions. Additionally, CsPETE2 from Camelina was induced by salt stress and AtPETE2 expression lines had larger primary roots and more lateral roots than the wild type. AtPETE2 expression lines also had larger seeds and higher total seed yield under long-term salt stress compared with non-transgenic Camelina. Our results demonstrate that increased plastocyanin levels in Camelina can enhance photosynthesis and productivity, as well as tolerance to osmotic and salt stresses. Heterologous expression of plastocyanin may be a useful strategy to mitigate crop stress in saline soils.

Nutrient enrichment triggers contrasting sexual reproductive responses in native and invasive plants in a saltmarsh

The effect of nutrient enrichment on the size differences between invasive and native plants has been widely documented, but the effect on their reproductive differences is less clear. We hypothesized that, under nutrient enrichment, the positive size-dependent response (increase as a consequence of the increased plant size) should dominate for invasive species, while the plastic response (decrease resulting from an altered reproductive allometric trajectory) should be stronger for noninvasive native species, resulting in an increase in the invasive species’ reproductive advantage. In a 2-year control experiment, we studied the effects of nutrient enrichment on the growth and reproduction (both sexual and clonal) of the dominant native and invasive plants from the low-marshes of Yangtze estuary in their respective monocultures and mixtures. Here we show that, nutrient enrichment generally reduced the reproduction of the native plant but increased that of the invasive plant. The disparity in reproductive responses between the two species can be attributed to the overriding effect of negative plastic response in the native plant, compared to the positive size-dependent response observed in the invasive plant. This study proposes that nutrient enrichment can confer the invasive plant an advantage in reproduction due to its difference in both size-dependent and plastic responses from the native competitor, demonstrating an overlooked pathway that nutrient enrichment hasten biological invasions.

A malformation of sex-changing plant Arisaema serratum (Araceae) produces both male and female inflorescences

ABSTRACT The genus Arisaema (Araceae) can change sex expression between male and female with increasing plant size (sequential hermaphrodism). As most Arisaema species have only one inflorescence on each individual, sex expression is seemingly determined at the individual level. However, malformations with male and female inflorescences have occasionally been observed. Unfortunately, their developmental origin is unclear because of a lack of detailed descriptions of the shoot structure. To estimate the unit of sex determination in Arisaema, we observed the morphology of an aberrant individual of Arisaema serratum (Thunberg) Schott with multiple inflorescences for three years. In the second year, the aberrant individual produced pure male and female inflorescences. Based on the phyllotactic pattern of this malformation, we estimated that the inflorescences were duplicated due to a broadening of the apical meristem via fasciation. Contrary to other Arisaema plants with multiple inflorescences reported previously, the corm of the aberrant individual did not subdivide nor branch spontaneously after the growing season for three years. Thus, duplicated inflorescences presumably shared the resource supply without physiological partitioning during sex determination. These results imply that sex expression is determined at the inflorescence level but not at the individual or floret levels in dioecious Arisaema.

Construction and expression of Wee1 recombinant protein in Escherichia coli strain BL21 (DE3)

Wee1 is a gene encoding for protein kinase that is located in the nucleus and it plays an essential role in determining the timing of mitosis. Overexpression of Wee1 in rice is resulting in increased plant size. However, the increasing plant size due to the increase of Wee1 protein expression is not elucidated. Immunodiagnostic using specific antibodies against Wee1 protein should be conducted to determine the role of the protein on cell division. This experiment was directed to construct Wee1 in an expression vector for synthesis of recombinant Wee1 protein using three strategies of construction. The three strategies were construction of full length (FL), deletion of putative binding site (BS), and deletion of N-terminal domain (ΔN) of Wee1. Restriction analysis with BamH1/Sal1 of FL-Wee1, BS-Wee1, and ΔN-Wee1 construct resulted in the different DNA fragments with molecular size at 1239, 1176, and 960bp, respectively. This result indicated that the Wee1 fragments have been successfully inserted in the expression plasmid which was further confirmed using DNA sequencing. Colony PCR analysis showed that Escherichia coli strain BL21 (DE3) has been transformed with the constructs. The protein analysis using SDS-PAGE revealed that the recombinant protein of Wee1 synthesized in the E.coli containing ΔN-Wee1 construct, but not in FL-Wee1 and BS-Wee1 constructs. The ΔN-Wee1 protein was synthesized in an insoluble fraction with a molecular size of 38.8 kDa which is the same as the size estimated using the software ExPASy. Interestingly, the level of synthesized ΔN-Wee1 protein was not induced by IPTG concentration. Collectively, the results indicated that the DNA construct of ΔN-Wee1 is suitable for recombinant protein production.

Precipitation regime changes alter allometry and plasticity of meristem allocation in annual herbaceous plants in a semiarid sandy grassland, northern China

AbstractThe three principal fates of axillary meristem in flowering plants are growth (G), reproduction (R), and inactivity (I). The allocation relationships between each meristem and plant size in annual herbaceous plants tend to change with altered precipitation (P) patterns in arid and semiarid grasslands. Here, we examined the allometry and plasticity of meristem allocation in three dominant annual herbaceous plants: Setaria viridis, Corispermum macrocarpum, and Bassia dasyphylla in a semiarid sandy grassland in northern China. We determined the range of plant sizes for each of the three species in the following treatments: ambient environment (Amb), P increased by 30% (P[+]) and by 60% (P[++]), P decreased by 30% (P[−]) and by 60% (P[− −]), drought for 46 days from May 1st to June 15th (D1) and from July 1st to August 15th (D2). We found that meristem allocation to branching intensity increased while allocation to apical dominance decreased with increasing plant size under decreased precipitation and seasonal drought. Decreased precipitation and seasonal drought caused the slope of allometry of meristem allocation in the three species to be significantly different from 1. Plasticity of meristem allocation to G, R, and I in S. viridis tended to be significantly greater in August under P(+) and P(++) while in C. macrocarpum tended to be greater in July under P(−), P(− −), D1, and D2. Our findings are important components of an adaptive strategy in annual herbaceous plants throughout the development stage, which will contribute to predict their developmental dynamics in the semiarid sandy grassland under future climate change.

Flowering Response of Cannabis sativa L. ‘Suver Haze’ under Varying Daylength-Extension Light Intensities and Durations

Daylength-extension lighting (DE) is used in the cannabis industry to increase plant size and produce cuttings by regulating flowering and extending the vegetative stage. Growers have reported incomplete or transitional inflorescences in several Cannabis cultivars even when exposed to long photoperiods. Cannabis sativa L. ‘Suver Haze’ has been reported to develop incomplete inflorescences in North Carolina nurseries using photoperiods of 15 h. The objectives of this study were to investigate the required light intensity and photoperiod to inhibit the flowering of ‘Suver Haze’. In Experiment 1, DE of 1.0, 2.5, 5.8, and 10.3 µmol·m−2·s−1 of photosynthetic photon flux density from incandescent lamps were used to extend the photoperiod of ‘Suver Haze’ from 9 to 15 h. A 9 h photoperiod control was included. The results showed that all DE treatments stopped the full transition to flowering compared to the control; however, all DE-treated plants showed the presence of incomplete inflorescences. In Experiment 2, three photoperiod treatments of 15 h, 18 h, and 21 h were tested. ‘Suver Haze’ under 18 h and 21 h photoperiods did not develop incomplete inflorescences in contrast to plants in 15 h photoperiod. Therefore, a light intensity of at least 1.0 µmol·m−2·s−1 PPFD and an 18 h photoperiod are required to prevent incomplete inflorescences and flowering of ‘Suver Haze’.

Size dependent allocation to vegetative and reproductive organs of the orchid &lt;i&gt;Lankesterella ceracifolia&lt;/i&gt; (Spiranthinae)

How functional organ traits vary with increasing plant size reveals the strategies of plants to acquire, store and utilize resources that ensure vegetative growth and reproduction. Plant size can influence fitness; thus, the relationships of organ traits should be evaluated together with reproductive allocation, but this is rarely the case. The relationship among plant size, functional organ traits (number and size of roots, leaves and flowers, and scape size), and dry mass partitioning was analyzed intraspecifically using 35 reproductive individuals of the epiphytic orchid Lankesterella ceracifolia. The relationships between vegetative and reproductive organ traits were evaluated using different regression models. Size-dependent allocation to reproduction was evaluated through reproductive versus vegetative (RV) regressions for the entire inflorescence and separately for scape and flowers. The four regression models included simple (slope only), linear (slope and intercept), allometric (without intercept), and non-linear (allometric with intercept), were fitted to RV and compared via a log likelihood-ratio test. Preferential allocation to leaves instead of roots influenced how rosette frontal area changed with increasing plant size. Flower dry mass represented 70% of the inflorescence dry mass, an unusual result as scape dry mass generally represents most of the reproductive structure in plants. The allometric model was suitable for the entire inflorescence or only the scape, while the isometric model was best for flowers. Dry mass investment in the scape influenced the final reproductive allometry found for the orchid L. ceracifolia.

Do larger plants produce more and better seeds and seedlings? Testing the hypothesis in a globose cactus, Wigginsia sessiliflora

In iteroparous plants, an increase in allocation to reproduction is expected with increasing plant size. The aim of this study was to analyze how plant diameter is related to total produced seed mass, seed number, mean seed mass, percentage and mean germination time (MGT), and seedling size and shape in Wigginsia sessiliflora (Hook.) D.M. Porter (Cactaceae), a slow-growing globose species from central Argentina. Plant diameter was measured in a population of 185 individuals, and fruits were collected. We counted all seeds to obtain seed number, and weighed them to get seed mass and total seed mass. Seeds were germinated and data of germination percentage and MGT were collected. We also measured the size (height and width) and shape of seedlings (height/width relationship). Fifty-four percent of the plants did not produce fruits. Plant diameter was unimodally related to fruit number, total seed mass, and seed number, i.e., intermediate-sized plants presented the highest values. Height and shape of seedlings were positively related to plant diameter. Surprisingly, plant diameter was related in a unimodal way to reproductive outputs. As plants grow, surface–volume ratio decreases, meaning that respiratory losses would be higher than the increase in photosynthetic capacity; therefore, fewer resources may be available for reproduction.

How seeds and growth dynamics influence plant size and yield: Integrating trait relationships into ontogeny

Abstract Seeds, growth rates and duration of growth influence plant development. However, we lack a mechanistic understanding of how they lead to larger and higher‐yielding plants, as these traits have not yet been explicitly studied in combination and across ontogeny. Seed size and growth dynamics have evolved differently during domestication and improvement. Nevertheless, it remains unclear whether the relationships between these traits and their contribution to plant size and yield have also changed over the course of crop evolution. Here we grew wild, landrace and improved accessions of 18 annual herbaceous crops in a glasshouse. For each plant, we measured seed mass, growth rate and duration of vegetative growth. We also measured plant size at three ontogenetic stages: seedling, juvenile and mature, and reproductive output. Using path analyses, we tested causal relationships between the traits and quantified their relative importance in determining mature plant size and yield. Seed mass and duration of vegetative growth were more important than growth rates in explaining variations in mature plant size and yield among species. Domesticated plants were larger, had heavier seeds and higher yields, but did not grow faster or for longer time‐spans than their wild progenitors. Trait relationships did not differ between the wild, landrace and improved accessions. Our results suggest that annual herbs reach larger sizes primarily through a combination of heavier seeds and longer vegetative growth periods. Moreover, domestication has increased plant size only through the heavy‐seed causal pathway, via cascading effects during ontogeny. However, the high yields of modern crops hardly be explained by the traits considered here, suggesting the importance of other drivers, such as roots and their microbiome. Synthesis. We provide a better mechanistic understanding of the size axis of global plant trait variation and emphasise the role of growth duration in explaining the diversity of mature plant sizes. Seeds and growth dynamics are highly functionally coordinated with plant size, and this coordination has changed little during crop evolution. Our results highlight that multi‐trait relationships throughout plant ontogeny play a key role in governing how domestication has influenced plant size and crop yields.

Fabric Containers Increased Irrigation Demand but Decreased Leachate Loss of Nitrogen and Phosphorus Compared With Conventional Plastic Containers During Production of Dwarf Burford Holly

Fabric containers (FAB), due to their root-pruning properties, can be used as an alternative to conventional plastic containers (PLA) in container nurseries. Because sidewall evaporation in FAB has been shown to reduce container substrate temperatures, our objective was to determine if FAB would reduce the release rate of controlled-release fertilizer (CRF), resulting in less leachate loss of nitrogen (N) and phosphorus (P) and greater CRF longevity. Dwarf Burford holly were grown in 36-cm-diameter (18-L substrate) FAB or PLA in a bark-peat substrate with incorporated CRF. Spray stake irrigation was routinely adjusted to a target leaching fraction of 25%. Maximum daily substrate temperature, measured 3 cm from southwest-facing container wall, averaged 6 °C lower in FAB than in PLA. For two 31-week experiments where leachate was continuously collected and sampled weekly, FAB reduced leachate N loss by 30% and P loss by 47% despite requiring 66% more irrigation water and collecting 31% more leachate than with PLA. FAB reduced average N loss from 114 to 78 kg·ha−1 and average P loss from 16.0 to 8.6 kg·ha−1. FAB increased plant size by 8% and shoot dry weight by 12% for one experiment but had no effect in the other. We concluded that compared with PLA, the use of FAB can decrease leachate loss of N and P but require considerably more irrigation water to offset water loss via sidewall evaporation.

Nitrogen Fertigation Rate and Foliar Urea Spray Affect Plant Growth, Nitrogen, and Carbohydrate Compositions of Encore Azalea ‘Chiffon’ Grown in Alternative Containers

The objective of this study was to investigate the plant vegetative growth, flower production, nitrogen (N) concentration, and carbohydrate compositions of Encore® azalea ‘Chiffon’ when fertigated with five N rates—0, 5, 10, 15, and 20 mM N—and grown in two types of containers, a black plastic and a biodegradable container, during one growing season. Foliar urea of 3% was applied to half of the plants in late fall to investigate its effect on plant N and carbohydrate concentrations. The paper biocontainers resulted in superior plant growth, increased plant size, dry weights, root length and surface area compared with the plastic containers with N rates of 10, 15, and 20 mM. The paper biocontainers also increased N uptake and carbohydrate concentrations mainly by increasing plant biomass. High N rates of 10 to 20 mM combined with urea spray and biocontainers generally resulted in the highest plant N concentrations. Foliar urea application in late fall tended to increase plant N concentration but decreased carbohydrates, including starch, glucose, fructose, and sucrose, to varying degrees, likely due to increased N assimilation. Fall foliar urea spray can be effective in improving the N status of azalea plants without affecting plant biomass.

Shrubification decreases soil organic carbon mineralization and its temperature sensitivity in alpine meadow soils

Shrubification is widespread in global grasslands. However, whether shrubification promotes the mineralization of soil organic carbon (SOC) remains uncertain. We compared sizes and compositions of soil non-cellulosic and amino sugar pools, soil stoichiometry, SOC decomposition and its temperature sensitivity between herbaceous and shrubby patches in alpine meadows on the Qinghai-Tibetan Plateau. The SOC content and soil stoichiometric C/P and N/P ratios in shrubby patches markedly increased with increasing plant size compared with herbaceous areas, indicating the increased P limitation to microorganisms relative to C and N with SOC accumulation under shrubs. The mass ratio of galactose plus mannose to arabinose plus xylose in the non-cellulosic carbohydrate pool of plant input was higher under shrubs than under grasses but was generally similar in soils between herbaceous and shrubby patches. This suggests the retarded microbial transformation of plant-derived carbohydrates under shrubs. Shrubs decreased accumulation of microbial necromass in SOC but increased the proportion of fungal origin in the microbial necromass. Lower total CO2 efflux per unit mass of SOC at either 15 °C or 25 °C from shrubby than from herbaceous patches over the 76-day incubation was mainly associated with the increased soil C/P or N/P ratio under shrubs. Shrubs decreased temperature sensitivity of SOC decomposition compared with grasses only at 20–40 cm soil depth, where microbial-synthesized substances had greater dominance over organic matter than at 0–20 cm depth and were less abundant under shrubs relative to grasses. Our findings show that increased P limitation to microorganisms in shrubification resulted in the decreased SOC decomposability and indicate that microbial-synthesized substances determined the temperature sensitivity of SOC mineralization. Therefore, shrubification mitigates CO2 emissions in grasslands by decreasing SOC mineralization and its temperature sensitivity in the context of global warming.

Size-dependent and environment-mediated shifts in leaf traits of a deciduous tree species in a subtropical forest.

AimsUnderstanding the joint effects of plant development and environment on shifts of intraspecific leaf traits will advance the understandings of the causes of intraspecific trait variation. We address this question by focusing on a widespread species Clausena dunniana in a subtropical broad‐leaved forest.MethodsWe sampled 262 individuals of C. dunniana at two major topographic habitat types, the slope and hilltop, within the karst forests in Maolan Nature Reserve in southwestern China. We measured individual plant level leaf traits (i.e., specific leaf area (SLA), leaf area, leaf dry‐matter content (LDMC), and leaf thickness) that are associated with plant resource‐use strategies. We adopted a linear mixed‐effects model in which the plant size (i.e., the first principal component of plant basal diameter and plant height) and environmental factors (i.e., topographic habitat, canopy height, and rock‐bareness) were used as independent variables, to estimate their influences on the shifts of leaf traits.Key ResultsWe found that (1) plant size and the environmental factors independently drove the intraspecific leaf trait shifts of C. dunniana, of which plant size explained less variances than environmental factors. (2) With increasing plant size, C. dunniana individuals had increasingly smaller SLA but larger sized leaves. (3) The most influential environmental factor was topographic habitat; it drove the shifts of all the four traits examined. Clausena dunniana individuals on hilltops had leaf traits representing more conservative resource‐use strategies (e.g., smaller SLA, higher LDMC) than individuals on slopes. On top of that, local‐scale environmental factors further modified leaf trait shifts.ConclusionsPlant size and environment independently shaped the variations in intraspecific leaf traits of C. dunniana in the subtropical karst forest of Maolan. Compared with plant size, the environment played a more critical role in shaping intraspecific leaf trait variations, and potentially also the underlying individual‐level plant resource‐use strategies.

Uji Cara Aplikasi PGPR dalam Menekan Kejadian Penyakit Antraknosa pada Tanaman Cabai Hiyung di Lahan Rawa

Chili Hiyung is a local chili variety typical of South Kalimantan. At this time began to be exposed to a lot of anthracnose disease. Control using pesticides needs to be avoided by finding more convenient control methods. Area-friendly disease control includes using PGPR (Plant Growth Promoting Rhizobacteria). The use of PGPR for chili plants in the swamp land of Hiyung village has not been studied, meanwhile its potential has been tested on several other plants. This research aims to identify the effect of PGPR in suppressing anthracnose disease in Chili Hiyung in the swamp land of Hiyung Village. The design used was a single aspect Completely Randomized Design (CRD) based on 4 (four) treatments, namely the leak, spray, or spray and leak methods. The results of the research show that the PGPR application does not affect the incidence of anthracnose disease in Hiyung chili plants in Hiyung village. But the PGPR application can increase plant size and fruit weight per branch.

Shape Matters: Plant Architecture Affects Chemical Uniformity in Large-Size Medical Cannabis Plants.

Since plant organs sense their environment locally, gradients of micro-climates in the plant shoot may induce spatial variability in the physiological state of the plant tissue and hence secondary metabolism. Therefore, plant architecture, which affects micro-climate in the shoot, may considerably affect the uniformity of cannabinoids in the Cannabis sativa plant, which has significant pharmaceutical and economic importance. Variability of micro-climates in plant shoots intensifies with the increase in plant size, largely due to an increase in inter-shoot shading. In this study, we therefore focused on the interplay between shoot architecture and the cannabinoid profile in large cannabis plants, ~2.5 m in height, with the goal to harness architecture modulation for the standardization of cannabinoid concentrations in large plants. We hypothesized that (i) a gradient of light intensity along the plants is accompanied by changes to the cannabinoid profile, and (ii) manipulations of plant architecture that increase light penetration to the plant increase cannabinoid uniformity and yield biomass. To test these hypotheses, we investigated effects of eight plant architecture manipulation treatments involving branch removals, defoliation, and pruning on plant morpho-physiology, inflorescence yield, cannabinoid profile, and uniformity. The results revealed that low cannabinoid concentrations in inflorescences at the bottom of the plants correlate with low light penetration, and that increasing light penetration by defoliation or removal of bottom branches and leaves increases cannabinoid concentrations locally and thereby through spatial uniformity, thus supporting the hypotheses. Taken together, the results reveal that shoot architectural modulation can be utilized to increase cannabinoid standardization in large cannabis plants, and that the cannabinoid profile in an inflorescence is an outcome of exogenous and endogenous factors.

Rhizobacterial Bacillus mycoides functions in stimulating the antioxidant defence system and multiple phytohormone signalling pathways to regulate plant growth and stress tolerance.

To analyse effects and mechanisms of plant growth promotion mediated by Bacillus mycoides strain A3 (BmA3), in Arabidopsis thaliana seedlings. Bacillus mycoides strain A3 (BmA3) isolated from the bamboo rhizosphere produced phytohormones, including indole-3-acetic acid (IAA) and gibberellic acid (GA), and exhibited phosphate solubilization and radical scavenging activities. A. thaliana seedlings inoculated with BmA3 exhibited an altered root architecture including an increased number of lateral roots and root hairs. Likewise, enhanced photosynthetic efficiency through the accumulation of higher levels of chlorophyll and starch, and increased plant size and fresh weight were observed in the BmA3-treated seedlings. This bacterial inoculation stimulated the antioxidant defence system by increasing the activities of catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and phenylalanine ammonia-lyase (PAL). Secondary metabolites, including phenolic compounds, flavonoids and glucosinolates, were induced to higher levels in the BmA3-treated plants. Under drought and heat stresses, lower levels of H2 O2 , malondialdehyde (MDA) and electrolyte leakage were noticed in the treated seedlings. Genes involved in the signalling pathway of jasmonic acid (JA) including MYC2 and lipoxygenase 1 (LOX1) and salicylic acid (SA) including SAR DEFICIENT 1 (SARD1) and CAM-BINDING PROTEIN 60-LIKE G (CBP60G), and the antioxidant defence system including Ascorbate peroxidase (AtAPX) and alternative oxidase (AOX) were upregulated in BmA3-treated plants. Moreover, pathogenesis-related protein 1 (PR-1) and PR-2, marker genes for disease resistance, as well as DREB2A and HsFA2, which function in abiotic stress regulation, were also upregulated. BmA3 was able to activate JA and SA signalling pathways to induce plant growth and abiotic stress tolerance in A. thaliana seedlings. The plant growth promotion and increased stress tolerance induced by BmA3 were the result of the combined effects of microbial metabolites and activated host plant responses, including phytohormone signalling pathways and antioxidant defence systems.

Interspecific interactions regulate plant reproductive allometry in cereal–legume intercropping systems

Abstract Calls for the application of ecological principles in agriculture have gained momentum. Intercropping systems are designed by growing two, or more, annual crop species in the same field, aiming for a better resource use efficiency. However, assembly rules for their design are lacking. Notably, it is unknown whether species performances are maximized during both the vegetative and reproductive phases given the sensitivity of reproductive allocation rules to resource limitation. Interestingly, ecological theory provides expectations regarding putative invariance of plant reproductive allometry (PRA) under non‐limiting conditions for plant growth. Here we examined whether and how PRA changes in response to plant–plant interactions in intercropping systems, which can inform both ecological theory and the understanding of the functioning of intercropping systems. We analysed a dataset of 28 field cereal–legume intercropping trials from various climatic and management conditions across Western Europe. PRA was quantified in both mixing and single‐species situations. Plant reproductive allometry was positively impacted in specific management conditions, leading to a greater increase in yield for a given increase in plant size. Variations in PRA were more beneficial to legumes grown in unfertilized mixtures, which explains their use as a key component in actual intercropping systems. The response for cereals was similar but less pronounced in magnitude, and was greater under resource‐limiting conditions. Focusing on intercropping conditions, hierarchical competition (indicated by biomass difference between intercropped species) appears as a strong driver of the reproductive output of a given species. Synthesis and applications. Plant reproductive allometry (PRA) behaves in crop species in the same way as it does in wild species. However, contrary to theoretical expectations about an overall invariance of PRA, we highlighted taxon‐specific and context‐dependent effects of plant–plant interactions on PRA. This systematic deviation to PRA expectations could be leveraged to cultivate each species up to its reproductive optimum while accounting for the performance of the other, whether farmer's objective is to favour one species or to reach an equilibrium in seed production. Sowing density and cultivar choice could regulate the biomass of each component, with specific targets derived from allometric relationships, aiming for an optimal reproductive allocation in mixtures.

Coordination between growth and stress responses by DELLA in the liverwort Marchantia polymorpha

Plant survival depends on the optimal use of resources under variable environmental conditions. Among the mechanisms that mediate the balance between growth, differentiation, and stress responses, the regulation of transcriptional activity by DELLA proteins stands out. In angiosperms, DELLA accumulation promotes defense against biotic and abiotic stress and represses cell division and expansion, while the loss of DELLA function is associated with increased plant size and sensitivity toward stress.1 Given that DELLA protein stability is dependent on gibberellin (GA) levels2 and GA metabolism is influenced by the environment,3 this pathway is proposed to relay environmental information to the transcriptional programs that regulate growth and stress responses in angiosperms.4,5 However, DELLA genes are also found in bryophytes, whereas canonical GA receptors have been identified only in vascular plants.6-10 Thus, it is not clear whether these regulatory functions of DELLA predated or emerged with typical GA signaling. Here, we show that, as in vascular plants, the only DELLA in the liverwort Marchantia polymorpha also participates in the regulation of growth and key developmental processes and promotes oxidative stress tolerance. Moreover, part of these effects is likely caused by the conserved physical interaction with the MpPIF transcription factor. Therefore, we suggest that the role in the coordination of growth and stress responses was already encoded in the DELLA protein of the common ancestor of land plants, and the importance of this function is underscored by its conservation over the past 450 million years.

Heterologous expression of ZmGS5 enhances organ size and seed weight by regulating cell expansion in Arabidopsis thaliana.

Maize ZmGS5 was reported to be positively associated with kernel-related traits, however, its regulatory mechanism on plant development and seed size remains unknown. In this study, ZmGS5 was demonstrated to be widely expressed in various maize tissues with the highest expression level in developing embryos, indicating its critical roles in early kernel development process. The ZmGS5 protein was subcellularly localized to both the nucleus and cytoplasm. Transgenic Arabidopsis plants overexpressing ZmGS5 under the control of either the constitutive maize Ubiquitin1 promotor or native ZmGS5 promoter resulted in increased plant size, biomass, seed size and weight, although no significant difference was observed between transgenic lines harboring the two constructs. In contrast, the antisense-ZmGS5 transgene resulted in opposite phenotypes. Our cytological data suggested that ZmGS5 enlarged petal size through enhancing cell expansion. Quantitative RT-PCR analysis indicated that ZmGS5 might enhance cell expansion and grain filling by upregulating expression levels of particular EXPA or SWEET genes. Collectively, these findings help us further understand the biological function and regulatory mechanism of ZmGS5 in improving organ size and seed weight, which imply its great potential for high-yield breeding in the future.