Arbuscular mycorrhiza influences carbon‐use efficiency and grain yield of wheat grown under pre‐ and post‐anthesis salinity stress

• Soil salinity severely affects and constrains crop production worldwide. Salinity causes osmotic and ionic stress, inhibiting gas exchange and photosynthesis, ultimately impairing plant growth and development. Arbuscular mycorrhiza (AM) have been shown to maintain light and carbon use efficiency under stress, possibly providing a tool to improve salinity tolerance of the host plants. Thus, it was hypothesized that AM will contribute to improved growth and yield under stress conditions.
• Wheat plants (Triticum aestivum L.) were grown with (AMF+) or without (AMF?) arbuscular mycorrhizal fungi (AMF) inoculation. Plants were subjected to salinity stress (200 mm NaCl) either at pre‐ or post‐anthesis or at both stages. Growth and yield components, leaf chlorophyll content as well as gas exchange parameters and AMF colonization were analysed.
• AM plants exhibited a higher rate of net photosynthesis and stomatal conductance and lower intrinsic water use efficiency. Furthermore, AM wheat plants subjected to salinity stress at both pre‐anthesis and post‐anthesis maintained higher grain yield than non‐AM salinity‐stressed plants.
• These results suggest that AMF inoculation mitigates the negative effects of salinity stress by influencing carbon use efficiency and maintaining higher grain yield under stress.

     

Arbuscular mycorrhiza‐mediated resistance in tomato against Cladosporium fulvum‐induced mould disease

Root colonization with arbuscular mycorrhizal fungi (AMF) enhances plant resistance particularly against soil‐borne pathogenic fungi. In this study, mycorrhizal inoculation with Glomus mosseae (Gm) significantly alleviated tomato mould disease caused by the air‐borne fungal pathogen, Cladosporium fulvum (Cf). The disease index (DI) in local leaves (receiving pathogen inoculation) and systemic leaves (just above the local leaf without pathogen inoculation) was 36.4% and 11.7% in mycorrhizal plants, respectively, whereas DI was 59.6% and 36.4% in the corresponding leaves of AMF non‐inoculated plants, after 50 days of Gm inoculation, corresponding to 15 days after Cf inoculation by leaf infiltration. Foliar spray inoculation with Cf also revealed that AMF pre‐inoculated plants had a higher resistance against subsequent pathogen infection, where the DI was 41.3% in mycorrhizal plants vs. 64.4% in AMF non‐inoculated plants. AMF‐inoculated plants showed significantly higher fresh and dry weight than non‐inoculated plants under both control (without pathogen) and pathogen treatments. AMF‐inoculated plants exhibited significant increases in activities of superoxide dismutase and peroxidase, along with decreases in levels of H₂O₂ and malondialdehyde, compared with non‐inoculated plants after pathogen inoculation. AMF inoculation led to increases in total chlorophyll contents and net photosynthesis rate as compared with non‐inoculated plants under control and pathogen infection. Pathogen infection on AMF non‐inoculated plants led to decreases in chlorophyll fluorescence parameters. However, pathogen infection did not affect these parameters in mycorrhizal plants. Taken together, these results indicate that AMF colonization may play an important role in plant resistance against air‐borne pathogen infection by maintaining redox poise and photosynthetic activity.     

Potential of efficient and resistant plant growth‐promoting rhizobacteria in lead uptake and plant defence stimulation in Lathyrus sativus under lead stress

• The ability of plant growth‐promoting rhizobacteria (PGPR) to enhance Lathyrus sativus tolerance to lead (Pb) stress was investigated.
• Ten consortia formed by mixing four efficient and Pb‐resistant PGPR strains were assessed for their beneficial effect in improving Pb (0.5 mM) uptake and in inducing the host defence system of L. sativus under hydroponic conditions based on various physiological and biochemical parameters.
• Lead stress significantly decreased shoot (SDW) and root (RDW) dry weight, but PGPR inoculation improved both dry weights, with highest increases in SDW and RDW of plants inoculated with I5 (R. leguminosarum (M5) + P. fluorescens (K23) + Luteibacter sp. + Variovorax sp.) and I9 (R. leguminosarum (M5) + Variovorax sp. + Luteibacter sp. + S. meliloti) by 151% and 94%, respectively. Additionally, inoculation significantly enhanced both chlorophyll and soluble sugar content, mainly in I5 inoculated leaves by 238% and 71%, respectively, despite the fact that Pb decreased these parameters. We also found that PGPR inoculation helps to reduce oxidative damage and enhances antioxidant enzyme activity, phenolic compound biosynthesis, carotenoids and proline content. PGPR inoculation increased Pb uptake in L. sativus, with highest increase in shoots of plants inoculated with I5 and I7, and in roots and nodules of plants inoculated with I1. Moreover, PGPR inoculation enhanced mineral homeostasis for Ca, Cu and Zn under Pb stress, mainly in plants inoculated with I1, I5, I7 and I9.
• Results of our study suggest the potential of efficient and Pb‐resistant PGPR in alleviating harmful effects of metal stress via activation of various defence mechanisms and enhancing Pb uptake that promotes tolerance of L. sativus to Pb stress.

     

Enterobacter asburiae KE17 association regulates physiological changes and mitigates the toxic effects of heavy metals in soybean

This study aimed to elucidate the role played by Enterobacter asburiae KE17 in the growth and metabolism of soybeans during copper (100 μm Cu) and zinc (100 μm Zn) toxicity. When compared to controls, plants grown under Cu and Zn stress exhibited significantly lower growth rates, but inoculation with E. asburiae KE17 increased growth rates of stressed plants. The concentrations of plant hormones (abscisic acid and salicylic acid) and rates of lipid peroxidation were higher in plants under heavy metal stress, while total chlorophyll, carotenoid content and total polyphenol concentration were lower. While the bacterial treatment reduced the abscisic acid and salicylic acid content and lipid peroxidation rate of Cu‐stressed plants, it also increased the concentration of photosynthetic pigments and total polyphenol. Moreover, the heavy metals induced increased accumulation of free amino acids such as aspartic acid, threonine, serine, glycine, alanine, leucine, isoleucine, tyrosine, proline and gamma‐aminobutyric acid, while E. asburiae KE17 significantly reduced concentrations of free amino acids in metal‐affected plants. Co‐treatment with E. asburiae KE17 regulated nutrient uptake by enhancing nitrogen content and inhibiting Cu and Zn accumulation in soybean plants. The results of this study suggest that E. asburiae KE17 mitigates the effects of Cu and Zn stress by reprogramming plant metabolic processes.     

The speciation and distribution characteristics of Cu in Phragmites australis (Cav.) Trin ex. Steudel

• Heavy metal allocation and the mechanism(s) of metal sequestration in different clonal organs, micro‐domains and subcellular structures has not been systematically studied for rhizomatous perennial plants. It is thus pertinent to investigate knowledge of the speciation and distribution characteristics of Cu in Phragmites australis to elucidating the mobility of metals in wetland plants after their uptake via root systems so as to facilitate development of strategies to enhance Cu tolerance.
• This study investigated the distributions of Cu in P. australis root, stem and leaf using ICP‐MS, synchrotron‐based X‐ray micro‐fluorescence and X‐ray absorption spectroscopy, then evaluated the effects of Cu on cellular structure and ultrastructure via transmission electron microscopy.
• The results indicate a clear preferential localisation of Cu in the roots as compared with the shoots (stems and leaves). The intensity of Cu in the vascular bundles was higher than that in the surrounding epidermis and the endodermis and parenchyma outside the medullary cavity. The dominant chemical form of Cu in P. australis was similar to Cu citrate.
• The results suggest that although Cu can be easily transported into the vascular tissues in roots and stems via Cu citrate, most of the metal absorbed by plants is retained in the roots because if its high binding to the cell wall, thus preventing metal translocation to aerial parts of the plants. Therefore, P. australis showed a high capacity to accumulate Cu in roots, being therefore a suitable species for phytostabilisation interventions.

     

Mechanism of application nursery cultivation arbuscular mycorrhizal seedling in watermelon in the field

Arbuscular mycorrhizal fungi (AMF) colonisation of plant root facilitates the absorption of nutrients such as phosphorus (P) and enhances plant biotic and abiotic resistance generally. However, arbuscular mycorrhiza (AM) colonisation decreases with application of chemical fertiliser. Here, we investigated whether AMF inoculation in nurseries would facilitate AM colonisation and take physiological and ecological functions in watermelon (Citrullus lanatus) in the field. Pot experiments were carried out to study the change of AMF colonised seedling on physiology and gene expression in nursery site. Field experiments were performed to investigate the effect of nursery AMF inoculation on yield, quality and disease resistance of watermelon in the field. The results showed that nursery‐inoculated seedlings produced more dry matter and root surface area than non‐inoculated seedlings. Expression of the secretory purple acid phosphatase (PAP) genes ClaPAP10 and ClaPAP26 was up‐regulated following AMF colonisation. Accordingly, acid phosphatase activities at the root surface and P concentrations in seedling were enhanced. After transplantation to the field, the shoot dry matter and P concentration in old stem were higher in the nursery AMF inoculated seedlings than that in non‐AMF inoculated seedling. AMF inoculation also induced increase of yields and decrease of wilt disease indexes and soluble sugar content. In addition, acid phosphatase activities and AMF spore densities were increased by nursery‐inoculation in watermelon rhizosphere soil in the field. In conclusion, nursery colonisation AMF seedling enhanced watermelon growth and yield by improving the root growth and P acquisition in nursery cultivating stage, as well as optimised soil properties in the field. Nursery cultivation of watermelon seedling with AMF was an effective technique to reduce wilt disease in continuous cropped management in watermelon.     

Effects of Preconditioning Through Mycorrhizal Inoculation on the Control of Melon Root Rot and Vine Decline Caused by Monosporascus cannonballus

The use of inoculum of arbuscular mycorrhizal fungi (AMF) in nursery represents a promising field in horticulture because of its known benefits in terms of plant growth and bioprotection. The present work was undertaken to determine the effect of mycorrhizal inoculation with Rhizophagus irregularis in a nursery medium on the containment of melon root rot and vine decline (MRRVD) caused by the soil‐borne pathogen Monosporascus cannonballus. The percentage of mycorrhization, biomass and yield following mycorrhizal inoculation were also evaluated. Biocontrol activity was assessed in greenhouse pot experiments upon artificial inoculation of M. cannonballus and in a two‐season field experiment under production conditions in an unheated greenhouse with a history of MRRVD. On the basis of the mycorrhization parameters, the interaction appeared to be established within 30 days after inoculation. The total shoot growth in the mycorrhized plants was significantly higher when compared to the control, while the root growth was unaffected. Upon artificial inoculation of M. cannonballus, mycorrhization provided complete protection against the pathogen. Greenhouse experiments under production conditions during spring cropping season showed that pretransplanting inoculation with R. irregularis significantly decreased the severity of the disease. Also, the average fruit weight of mycorrhized plants was significantly higher than the untreated control. Nevertheless, in summer crop, the bioprotection activity of AMF failed. Present results indicate that the use of AMF in a nursery setting can contribute to the prevention of the onset of this problematic soil‐borne disease within a sustainable and integrated soil‐borne disease management.     

Piriformospora indica inoculation alleviates the adverse effect of NaCl stress on growth,gas exchange and chlorophyll fluorescence in tomato (Solanum lycopersicum L.)

• Salinity is now an increasingly serious environmental issue that affects the growth and yield of many plants.
• In the present work, the influence of inoculation with the symbiotic fungus, Piriformospora indica, on gas exchange, water potential, osmolyte content, Na/K ratio and chlorophyll fluorescence of tomato plants under three salinity levels (0, 50, 100 and 150 mm NaCl) and three time periods (5, 10 and 15 days after exposure to salt) was investigated.
• Results indicate that P. indica inoculation improved growth parameters of tomato under salinity stress. This symbiotic fungus significantly increased photosynthetic pigment content under salinity, and more proline and glycine betaine accumulated in inoculated roots than in non‐inoculated roots. P. indica further significantly improved K⁺ content and reduced Na⁺ level under salinity treatment. After inoculation with the endophytic fungus, leaf physiological parameters, such as water potential, net photosynthesis, stomatal conductance and transpiration, were all higher under the salt concentrations and durations compared with controls without P. indica. With increasing salt level and salt treatment duration, values of F₀ and qP increased but F_m, F_v/F_m, F′_v/F′_m and NPQ declined in the controls, while inoculation with P. indica improved these values.
• The results indicate that the negative effects of NaCl on tomato plants were alleviated after P. indica inoculation, probably by improving physiological parameters such as water status and photosynthesis.

     

Melatonin mitigates cadmium and aluminium toxicity through modulation of antioxidant potential in Brassica napus L

• Melatonin has emerged as an essential molecule in plants, due to its role in defence against metal toxicity. Aluminium (Al) and cadmium (Cd) toxicity inhibit rapeseed seedling growth.
• In this study, we applied different doses of melatonin (50 and 100 µm ) to alleviate Al (25 µm ) and Cd (25 µm ) stress in rapeseed seedlings. Results show that Al and Cd caused toxicity in rapeseed seedling, as evidenced by a decrease in height, biomass and antioxidant enzyme activity.
• Melatonin increased the expression of melatonin biosynthesis‐related Brassica napus genes for caffeic acid O‐methyl transferase (BnCOMT) under Al and Cd stress. The genes BnCOMT‐1, BnCOMT‐5 and BnCOMT‐8 showed up‐regulated expression, while BnCOMT‐4 and BnCOMT‐6 were down‐regulated during incubation in water. Melatonin application increased the germination rate, shoot length, root length, fresh and dry weight of seedlings. Melatonin supplementation under Al and Cd stress increased superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, proline, chlorophyll and anthocyanin content, as well as photosynthesis rate. Both Cd and Al treatments significantly increased hydrogen peroxide and malondialdehyde levels in rapeseed seedlings, which were strictly counterbalanced by melatonin. Analysis of Cd and Al in different subcellular compartments showed that melatonin enhanced cell wall and soluble fractions, but reduced the vacuolar and organelle fractions in Al‐ and Cd‐treated seedlings.
• These results suggest that melatonin‐induced improvements in antioxidant potential, biomass, photosynthesis rate and successive Cd and Al sequestration play a pivotal role in plant tolerance to Al and Cd stress. This mechanism may have potential implications in safe food production.

     

西南桦幼苗接种丛枝菌根真菌的生长与光合生理响应

为了解丛枝菌根真菌(arbuscular mycorrhiza,AMF)对西南桦幼苗生长和光合生理的影响,对西南桦(Betula alnoides)优良无性系接种AMF菌株后的生长、光合参数、叶绿素含量和荧光参数进行了研究。结果表明,6个AMF菌株均能与西南桦无性系幼苗形成共生体,接种根内球囊霉(Glomus intraradices)菌株(AMF5)和摩西球囊霉(G.mosseae)HUN03B菌株(AMF3)显著提高了幼苗生长量、净光合速率、水分利用效率、叶绿素含量和荧光参数(P0.05),显示出AMF5、AMF3与幼苗的亲和力明显优于其他菌株。西南桦4个无性系间的菌根侵染率差异不显著(P0.05),但AMF对无性系FB4、BY1的促生效应显著优于FB4+和A5。因此,适合与西南桦共生的优良菌株为AMF5和AMF3,这为西南桦菌根化育苗提供理论依据。     

干旱胁迫下AMF对云南蓝果树幼苗生长和光合特征的影响

采用盆栽试验与称重控水法,将土壤相对含水量分别控制在田间最大持水量的100%、91.68%、82.85%、60.00%、41.86%和21.28%,并在这6个不同的土壤相对含水量条件下,分别设添加苯菌灵(杀真菌剂)(低AMF)和不添加苯菌灵(高AMF)处理,研究干旱胁迫下AMF对极小种群野生植物云南蓝果树幼苗生长和光合特征的影响,揭示云南蓝果树濒危的微生物学机制,为云南蓝果树保护措施的制定与实施奠定基础。结果表明,添加苯菌灵处理显著降低了不同水分条件下的AMF侵染率,说明试验中AMF处理的实生苗在生长和光合特征上的差异是苯菌灵处理下侵染率下降导致的;随着干旱胁迫的加剧,云南蓝果树幼苗的根部AMF侵染率显著降低、叶面积等生长指标和净光合速率(Pn)等光合参数都发生显著变化;高AMF处理可以显著增加水分充足和轻度干旱胁迫条件下云南蓝果树幼苗的大部分生长指标和光合参数,而对重度胁迫下的云南蓝果树幼苗没有显著影响,说明重度干旱胁迫对其影响大于AMF的影响;另外,整合了可塑性指数分析和隶属函数分析两种方法对其抗旱性进行评价,云南蓝果树幼苗基本上无法通过调节形态和光合能力来适应水分环境的变化,但是高AMF处理可使云南蓝果树幼苗具有较强的可塑性和更强的抗旱性。实验结果为云南蓝果树的科学保育及种苗繁育提供了理论依据。     

干旱胁迫条件下AMF促进小马鞍羊蹄甲幼苗生长的机理研究

采用温室水分控制试验,在干旱胁迫条件下,定量化研究优势丛枝菌根真菌(AMF)影响优势乡土植物小马鞍羊蹄甲(Bauhinia faberi var.microphylla)幼苗生长的机理,主要通过研究干旱胁迫条件下摩西球囊霉菌(Funneliformis mosseae)与小马鞍羊蹄甲的共生关系,阐明AMF在植物生长初期的作用。结果表明,干旱胁迫条件下,摩西球囊霉菌能够很好地侵染幼苗,侵染率高达89%—97%,并且不受水分条件影响。接种的幼苗最大光合速率、水分利用效率随着干旱胁迫程度从重度到轻度(水分从低到高)逐渐增大,相反地,叶片脯氨酸含量逐渐减小。接种显著地促进幼苗株高、叶片数、叶面积、根长、根面积等生长指标,提高幼苗各部分生物量、地上地下磷(P)含量。当含水量为60%田间持水量时,AMF促进小马鞍羊蹄甲幼苗吸收P的效果最好。接种还显著影响幼苗的生物量分配,在重度干旱胁迫时影响P分配,水分条件也显著影响幼苗的生物量分配。此外,接种和水分的交互作用对叶生物量、总生物量、生长指标以及地上部氮(N)总量影响显著。结果表明干旱胁迫条件下菌根效应显著,并在干旱条件下显著促进了小马鞍羊蹄甲幼苗的生长,这为进一步干旱河谷植被恢复提供了理论依据。     

Brassinosteroids are involved in ethylene‐induced Pst DC3000 resistance in Nicotiana benthamiana

• Plant immunity is regulated by a huge phytohormone regulation network. Ethylene(ET) and brassinosteroids (BRs) play critical roles in plant response to biotic stress; however, the relationship between BR and ET in plant immunity is unclear.
• We used chemical treatments, genetic approaches and inoculation experiments to investigate the relationship between ET and BR in plant defense against Pst DC3000 in Nicotiana benthamiana.
• Foliar applications of ET and BR enhanced plant resistance to Pst DC3000 inoculation, while treatment with brassinazole (BRZ, a specific BR biosynthesis inhibitor) eliminated the ET induced plant resistance to Pst DC3000. Silencing of DWARF 4(DWF4, a key BR biosynthetic gene), BRASSINOSTEROID INSENSITIVE 1 (BRI1, aBR receptor) and BRASSINOSTEROID-SIGNALING KINASE 1 (BSK1, downstream of BRI1) also neutralised the ET‐induced plant resistance to Pst DC3000. ET can induce callose deposition and reactive oxygen species (ROS) accumulation to resistPst DC3000, BRZ‐treated and gene‐silenced were completely eliminate this response.
• Our results suggest BR is involved in ET‐induced plant resistance, the involvement of ET in plant resistance is possibly by the induction of callose deposition and ROS accumulation, in a BR‐dependent manner.

     

Physio‐biochemical assessment and expression analysis of genes associated with drought tolerance in sugarcane (Saccharum spp. hybrids) exposed to GA3 at grand growth stage

• Drought is one of the most serious environmental factors limiting production of sugarcane worldwide. In order to assess the influence of gibberellins (GA₃) on drought and plant growth, along with associated physio‐biochemical attributes, expression of eight drought‐responsive genes were quantified and analysed.
• At grand growth stage (120 DAP) two sugarcane varieties (CoLk94184, CoPK05191) were exposed to drought by withholding irrigation. GA₃ (35 ppm) was applied using battery‐operated uniform controlled dispensing sprayer twice at 1‐week intervals on 2‐week drought‐stressed plants. Physio‐biochemical attributes including antioxidant enzyme activities were estimated following standard protocols. RT‐PCR was performed to visualise the drought‐associated gene expression patterns.
• Drought triggered a reduction in RWC and chlorophyll content but these recovered when droughted plants were exposed to GA₃. Proline content increased many fold in both varieties under stress, but decreased under the influence of GA₃. There was a mixed response of antioxidant enzyme activity, which distinctly declined after GA₃ exposure, together with a lesser reduction in dry matter content over that of control plants. With increasing stress, expression of pyrroline‐5‐carboxylase synthetase (P5CS) and betaine‐aldehyde dehydrogenase genes was observed, selectively up‐regulated in CoPK05191. Expression of proline oxidase/transporter was high in CoPK05191 but diminished along with proline content after exposure to GA_3. CoLk94184 showed no significant difference in P5CS gene expression under stress condition, whereas expression of betaine‐aldehyde dehydrogenase gene was unchanged in response to stress.
• Results demonstrated that exposure of droughted plants to GA₃ not only led to recovery of activity of drought‐associated physio‐biochemical attributes, but also minimised impact on cane dry weight and quality. Further, GA₃ application caused differential gene expression that possibly triggers increased responsiveness towards drought tolerance in sugarcane.

     

不同水分处理下双接种丛枝菌根真菌和根瘤菌对疏叶骆驼刺生长及氮素转移的影响

以疏叶骆驼刺为研究对象,设定3个水分梯度正常水分(土壤相对含水量(70±5)%)、干旱胁迫(土壤相对含水量(20±5)%)和复水处理(干旱胁迫60天后恢复至正常水分)与四组接种处理(单接种丛枝菌根真菌(AMF)、单接种根瘤菌、双接种AMF+根瘤菌和不接种),分析不同水分条件下双接种丛枝菌根真菌和根瘤菌对疏叶骆驼刺的生长以及供、受体疏叶骆驼刺之间氮素转移的影响。结果表明,正常水分处理时,双接种疏叶骆驼刺的AMF侵染率、地上生物量、地下生物量、总生物量以及氮含量均要高于单接种处理;根瘤数量、最大荧光(Fm)、初始荧光(Fo)、最大光化学效率(Fv/Fm)与单接种处理之间无差异;在遭遇干旱胁迫时,双接种疏叶骆驼刺的AMF侵染率、总生物量、Fv/Fm均小于单接种处理;地上生物量、地下生物量、根瘤数、Fm、Fo以及氮含量与单接种之间无差异。复水后,双接种疏叶骆驼刺的地上生物量、地下生物量、总生物量、根瘤数均优于单接种;AMF侵染率、氮含量低于单接种;Fm、Fo、Fv/Fm均与单接种之间无差异。在氮素转移方面,正常水分时,双接种与单接种的氮素转移率无差异,在遭遇干旱胁迫时,双接种疏叶骆驼刺的氮素转...     

Life‐history trade‐offs vary with resource availability across the geographic range of a widespread plant

• Trade‐offs between reproduction, growth and survival arise from limited resource availability in plants. Environmental stress is expected to exacerbate these negative correlations, but no studies have evaluated variation in life‐history trade‐offs throughout species geographic ranges. Here we analyse the costs of growth and reproduction across the latitudinal range of the widespread herb Plantago coronopus in Europe.
• We monitored the performance of thousands of individuals in 11 populations of P. coronopus, and tested whether the effects of growth and reproduction on a set of vital rates (growth, probability of survival, probability of reproduction and fecundity) varied with local precipitation and soil fertility. To account for variation in internal resources among individuals, we analysed trade‐offs correcting for differences in size.
• Growth was negatively affected by previous growth and reproduction. We also found costs of growth and reproduction on survival, reproduction probability and fecundity, but only in populations with low soil fertility. Costs also increased with precipitation, possibly due to flooding‐related stress. In contrast, growth was positively correlated with subsequent survival, and there was a positive covariation in reproduction between consecutive years under certain environments, a potential strategy to exploit temporary benign conditions.
• Overall, we found both negative and positive correlations among vital rates across P. coronopus geographic range. Trade‐offs predominated under stressful conditions, and positive correlations arose particularly between related traits like reproduction investment across years. By analysing multiple and diverse fitness components along stress gradients, we can better understand life‐history evolution across species’ ranges, and their responses to environmental change.

     

The outer membrane Omp85‐like protein P39 influences metabolic homeostasis in mature Arabidopsis thaliana

• The Omp85 proteins form a large membrane protein family in bacteria and eukaryotes. Omp85 proteins are composed of a C‐terminal β‐barrel‐shaped membrane domain and one or more N‐terminal polypeptide transport‐associated (POTRA) domains. However, Arabidopsis thaliana contains two genes coding for Omp85 proteins without a POTRA domain. One gene is designated P39, according to the molecular weight of the encoded protein. The protein is targeted to plastids and it was established that p39 has electrophysiological properties similar to other Omp85 family members, particularly to that designated as Toc75V/Oep80.
• We analysed expression of the gene and characterised two T‐DNA insertion mutants, focusing on alterations in photosynthetic activity, plastid ultrastructure, global expression profile and metabolome.
• We observed pronounced expression of P39, especially in veins. Mutants of P39 show growth aberrations, reduced photosynthetic activity and changes in plastid ultrastructure, particularly in the leaf tip. Further, they display global alteration of gene expression and metabolite content in leaves of mature plants.
• We conclude that the function of the plastid‐localised and vein‐specific Omp85 family protein p39 is important, but not essential, for maintenance of metabolic homeostasis of full‐grown A. thaliana plants. Further, the function of p39 in veins influences the functionality of other plant tissues. The link connecting p39 function with metabolic regulation in mature A. thaliana is discussed.