Functional Plant Biology最新文献

Soybean (Glycine max ) is the world's most widely grown seed legume. One of the most important pests that decrease seed quality and reduce yield of soybean crops is the southern green stink bug (Nezara viridula ). Insect damage triggers accumulation of defensive compounds such as protease inhibitors (PIs), isoflavonoids and reactive oxygen species, which are regulated by the lipoxygenase (LOX)-regulated jasmonic acid (JA) to stop insect feeding. This study identified and characterised the role of LOX isoforms in the modulation of chemical defences in seeds of field-grown soybean that decreased digestive enzyme activities of N. viridula after insect attack. Stink bugs attack increased LOX 1 and LOX 2 expression, and activities of LOX 1 and LOX 3 isoenzymes in developing soybean seeds. In addition, stink bug damage and methyl jasmonate application induced expression and activity of both cysteine PIs and trypsin PIs in developing soybean seeds, suggesting that herbivory induced JA in soybean seeds. High PI activity levels in attacked seeds decreased cysteine proteases and α-amylases activities in the gut of stink bugs that fed on field-grown soybean. We demonstrated that LOX isoforms of seeds are concomitantly induced with JA-regulated PIs by stink bugs attack, and these PIs inhibit the activity of insect digestive enzymes. To our knowledge, this is the first study to investigate the participation of LOX in modulating JA-regulated defences against stink bugs in seeds of field-grown soybean, and our results suggest that soybean PIs may inhibit α-amylase activity in the gut of N. viridula .

Chickpea (Cicer arietinum ) is a grain crop that is an important source of protein, vitamins, carbohydrates and minerals. It is highly sensitive to salt stress, and salt damage to cellular homeostasis and protein folding affects production. Plants have several mechanisms to prevent cellular damages under abiotic stresses, such as proteins in the endoplasmic reticulum (protein isulfide somerases (PDIs) and PDI-like proteins), which help prevent the build-up of mis-folded proteins that are damaged under abiotic stresses. In this study, we completed initial comprehensive genome-wide analysis of the chickpea PDI gene family. We found eight PDI genes are distributed on six out of eight chromosomes. Two pairs of paralogous genes were found to have segmental duplications. The phylogenetic analysis showed that the PDI s have a high degree of homology in C. arietinum, Cicer reticulatum, Lens culinaris, Phaseolus acutifolius, Pisum sativum and Oryza sativa . The gene structure analysis displayed that CaPDI1-CaPDI8 have 9-12 exons except for CaPDI5 , which has 25 exons. Subcellular localisation indicated accumulation of CaPDIs in endoplasmic reticulum. Protein-conserved motifs and domain analysis demonstrated that thioredoxin domains of PDI family is present in all CaPDIs. CaPDI proteins have strong protein-protein interaction. In silico expression analysis showed that four out of eight PDI genes (CPDI2, CaPDI6, CaPDI7 and CaPDI8 ) were expressed under salt stress. Of these, expression of CaPDI2 and CaPDI8 was the highest. This work indicated that PDI genes are involved in salt stress tolerance in chickpea and the CaPDIs may be further studied for their role of inducing salt tolerance.

Flooding significantly hampers global forage production. In flood-prone regions, Lotus tenuis and Lotus corniculatus are common forage legumes, yet little is known about their responses to partial or complete submergence. To address this, we evaluated 10 Lotus accessions subjected to 11days of either partial or complete submergence, analysing growth traits related to tolerance and recovery after de-submergence. Principal component analyses revealed that submergence associated growth parameters were linked to L. corniculatus accessions, whereas recovery was associated with L. tenuis accessions. Notably, in L. tenuis , recovery from complete submergence positively correlated with leaf mass fraction but negatively with root mass fraction, showing an opposite pattern than in L. corniculatus . Encouragingly, no trade-off was found between inherent growth capacity and submergence tolerance (both partial and complete) or recovery ability, suggesting genetic selection for increased tolerance would not compromise growth potential. L. tenuis exhibited accessions with both partial and complete submergence tolerance, making them versatile for flood-prone environments, whereas L. corniculatus accessions were better suited for partial submergence. These findings offer valuable insights to enhance forage production in flood-prone areas and guide the selection of appropriate Lotus accessions for specific flood conditions.

Plants perceive N-acetyl-d-glucosamine-containing oligosaccharides that play a role in the interaction with bacteria and fungi, through cell-surface receptors containing a tight bundle of three LysM domains in their extracellular region. However, the identification of LysM domains of receptor-like kinases (RLK)/receptor-like proteins (RLP) using sequence based methods has led to some ambiguity, as some proteins have been annotated with only one or two LysM domains. This missing annotation was likely produced by the failure of the LysM hidden Markov model (HMM) from the Pfam database to correctly identify some LysM domains in proteins of plant origin. In this work, we provide improved HMMs for LysM domain detection in plants, that were built from the structural alignment of manually curated LysM domain structures from the Protein Data Bank and AlphaFold Protein Structure Database. Furthermore, we evaluated different sets of ligand-specific HMMs that were able to correctly classify a limited set of fully characterised RLK/Ps by their ligand specificity. In contrast, the phylogenetic analysis of the extracellular region of RLK/Ps, or of their individual LysM domains, was unable to discriminate these proteins by their ligand specificity. The HMMs reported here will allow a more sensitive detection of plant proteins containing LysM domains and help improve their characterisation.

Viscum schimperi is an evergreen hemiparasitic plant that can grow on stems and branches of several tree species. It penetrates the host tissues and forms a vascular bridge (haustorium) to withdraw the nutritive resources. Its relationships with hosts remain unknown. This study aimed to investigate the physiological and biochemical attributes of the host-hemiparasite association Acacia gerrardii -Viscum schimperi . The hemiparasite exhibited 2.4- and 3.0-fold lower photosynthetic activity and water use efficiency, and 1.2- and 4.1-fold higher transpiration rate and stomatal conductance. Equally, it displayed 4.9- and 2.6-fold greater water potential and osmotic potential, and in least 3.0times more accumulated 39 K, 85 Rb and 51 V, compared to the host. Nevertheless, it had no detrimental effect on photosynthetic activity, water status and multi-element accumulations in the host. Based on metabolome profiling, V. schimperi could use xanthurenic acid and propylparaben to acquire potassium from the host, and N -1-naphthylacetamide and N -Boc-hydroxylamine to weaken or kill the distal part of the infected branch and to receive the total xylem contents. In contrast, A. gerrardii could used N -acetylserotonin, arecoline, acetophenone and 6-methoxymellein to defend against V. schimperi infection.

Barley (Hordeum vulgare ) is the world's fourth most important cereal crop, and is particularly well adapted to harsh environments. However, lodging is a major productivity constraint causing 13-65% yield losses. Gibberellic acid (GA) homeostatic genes such as HvGA20ox, HvGA3ox and HvGA2ox are responsible for changes in plant phenotype for height and internodal length that contribute towards lodging resistance. This study explored the expression of different HvGAox transcripts in two contrasting barley genotypes (5-GSBON-18, lodging resistant; and 5-GSBON-70, lodging sensitive), which were sown both under controlled (hydroponic, completely randomised factorial design) and field conditions (split-plot, completely randomised block design) with two irrigation treatments (normal with three irrigation events; and water deficit with one irrigation event). In the hydroponic experiment, expression analysis was performed on seedlings at 0, ¾, 1½, 3 and 6h after application of treatment. In the field experiment, leaf, shoot nodes and internodes were sampled. Downregulation of HvGA20ox.1 transcript and 2-fold upregulation of HvGA2ox.2 transcript were observed in 5-GSBON-18 under water deficit conditions. This genotype also showed a significant reduction in plant height (18-20%), lodging (<10%), and increased grain yield (15-18%) under stress. Utilisation of these transcripts in barley breeding has the potential to reduce plant height, lodging and increased grain yield.

Pigeonpea (Cajanus cajan ) production can be affected by the spotted pod borer (Maruca vitrata ). Here, we identified biochemical changes in plant parts of pigeonpea after M. vitrata infestation. Two pigeonpea genotypes (AL 1747, moderately resistant; and MN 1, susceptible) were compared for glyoxalase and non-glyoxalase enzyme systems responsible for methylglyoxal (MG) detoxification, γ-glutamylcysteine synthetase (γ-GCS), glutathione-S-transferase (GST) and glutathione content in leaves, flowers and pods under control and insect-infested conditions. MN 1 had major damage due to M. vitrata infestation compared to AL 1747. Lower accumulation of MG in AL 1747 was due to higher activities of enzymes of GSH-dependent (glyoxylase I, glyoxylase II), GSH-independent (glyoxalase III) pathway, and enzyme of non-glyoxalase pathway (methylglyoxal reductase, MGR), which convert MG to lactate. Decreased glyoxylase enzymes and MGR activities in MN 1 resulted in higher accumulation of MG. Higher lactate dehydrogenase (LDH) activity in AL 1747 indicates utilisation of MG detoxification pathway. Higher glutathione content in AL 1747 genotype might be responsible for efficient working of MG detoxification pathway under insect infestation. Higher activity of γ-GCS in AL 1747 maintains the glutathione pool, necessary for the functioning of glyoxylase pathway to carry out the detoxification of MG. Higher activities of GST and GPX in AL 1747 might be responsible for detoxification of toxic products that accumulates following insect infestation, and elevated activities of glyoxylase and non-glyoxylase enzyme systems in AL 1747 after infestation might be responsible for reducing reactive cabanoyl stress. Our investigation will help the future development of resistant cultivars.

Floods and droughts are becoming more frequent as a result of climate change and it is imperative to find ways to enhance the resilience of staple crops to abiotic stresses. This is crucial to sustain food production during unfavourable conditions. Here, we analyse the current knowledge about suberised and lignified outer apoplastic barriers, focusing on the functional roles of the barrier to radial O2 loss formed as a response to soil flooding and we discuss whether this trait also provides resilience to multiple abiotic stresses. The barrier is composed of suberin and lignin depositions in the exodermal and/or sclerenchyma cell walls. In addition to the important role during soil flooding, the barrier can also restrict radial water loss, prevent phytotoxin intrusion, salt intrusion and the main components of the barrier can impede invasion of pathogens in the root. However, more research is needed to fully unravel the induction pathway of the outer apoplastic barriers and to address potential trade-offs such as reduced nutrient or water uptake. Nevertheless, we suggest that the outer apoplastic barriers might act as a jack of all trades providing tolerance to multiple abiotic and/or biotic stressors.

Flooding is a predominant abiotic stress for cultivated plants, including barley. This cereal crop shows a large adaptability to different environmental conditions, suggesting the presence of key traits to tolerate adverse conditions. During germination, genetic variations account for dissimilarities in flooding tolerance. However, differences in the seed microbiota may also contribute to tolerance/sensitivity during seedling establishment. This work investigated differences in microbiome among the grains of barley accessions. Two barley phenotypes were compared, each either tolerant or sensitive to a short submergence period followed by a recovery. The study used a metataxonomic analysis based on 16S ribosomal RNA gene sequencing and subsequent functional prediction. Our results support the hypothesis that bacterial microbiota inhabiting the barley seeds are different between sensitive and tolerant barley accessions, which harbour specific bacterial phyla and families. Finally, bacteria detected in tolerant barley accessions show a peculiar functional enrichment that suggests a possible connection with successful germination and seedling establishment.

Underwater germination could risk seedling survival, suggesting the need for control through seed perception of environmental cues. These cues include diurnally alternating temperatures tied to drained soils or shallow water tables. We examined high-amplitude alternating temperatures impact on underwater germination. Besides, the conditions experimented by seeds in the soil (e.g. hydration/dehydration phases) change their germinability so we tested if osmopriming could affect underwater germination. We worked with Echinochloa colona seedlots from extensive crop fields, exposing seeds to sequential submergence and drained treatments in combination with cues that promote germination. While a 10°C difference between maximum and minimum daily temperatures maximised germination in drained conditions, higher amplitudes (>15°C) alternating temperatures promoted E. colona underwater germination under hypoxic water (pO2 <4.1kPa). KNO3 osmopriming in drained conditions promoted later underwater germination even under hypoxic water; however, PEG 6000 osmopriming induced seeds to enter secondary dormancy inhibiting underwater germination. KNO3 improved E. colona underwater germination under air-equilibrated floodwater (pO2 : 16.5-17.4kPa) yet not under hypoxic conditions. This suggests that germination can proceed in flooded nitrate-fertile soils as long as it remains aerobic. Hypoxic submergence did not inhibit the induction of hypersensitivity to light in E. colona seeds. This research expands our understanding of wetland seed germination ecophysiology, shedding light on the inducible nature of underwater germination in hydrophyte weeds.