Shoot Growth Research Articles

Effect of Supplemental UV-B Radiation and Water Limitation on Plant Growth, Yield and Berry Composition of the Greek Grapevine Cultivar “Romeiko” Under Mediterranean Field Conditions

This work aims to evaluate the performance of the grapevine (Vitis vinifera L.) cultivar Romeiko under the influence of limited water availability and additional UV-B radiation exposure, applied alone or in combination. Three-year-old grapevines were exposed to two water regimes (well watered and water stressed) and two levels of UV-B radiation (ambient UV-B and ambient plus 15% UV-B). Predawn leaf water potential (ΨPD) and leaf relative water content (RWC) were significantly higher in well watered plants and on the other hand, no significant effect of UV-B on leaf tissue hydration was revealed. Both abiotic stressors significantly affected shoot growth rate (SGR), leaf fresh weight (FW) and leaf dry eight (DW), with the effect of water shortage on vegetative growth being more pronounced. Deficit irrigation had negative effects on yield both because of the reduced berry fresh weight and the lesser number of berries per cluster, while the yield response (quantity and quality attributes) of cv. Romeiko was similar between the two UV-B radiation regimes. In summary, limited water supply had a high potential for restricting vegetative growth and yield, whereas the effects of enhanced UV-B radiation were less evident on allometric parameters and nonexistent on fruit yield and quality characteristics. In addition, the combination of supplemental UV-B and deficit irrigation did not cause any pronounced effects compared to the single application of limited water supply.

Application of Ozonated Water to the Roots Increases Growth and Secondary Metabolite Accumulation in Brassicaceae Plants in a Hydroponics System

ABSTRACT This study aimed to analyze changes in growth parameters and secondary metabolites by intermittently applying ozonated water (OW) to the roots of red mustard, leaf mustard, and kale, grown in a nutrient film technique hydroponic system. During the period when the plants were cultivated for 3 weeks, OW at concentrations of 1 and 3 μL·L− 1 was flushed for 0, 1, 2, 4, and 8 minutes, twice a week, for a total of six treatments. In red mustard, the 1 μL·L− 1 OW treatment for 2 minutes resulted in the most significant increases in shoot fresh weight, shoot dry weight, leaf area, and an elevated shoot/root ratio. For leaf mustard, both the 1 and 3 μL·L− 1 treatments led to notable improvements in shoot fresh weight, total glucosinolate (GSL) content, and shoot/root ratio. During the two concentrations of OW, kale exhibited substantial significant increases in total GSL content, total anthocyanin content, total phenolic content, and shoot/root ratio. These results suggest that flushing OW to the plant roots in hydroponics systems, particularly at a concentration of 1 μL·L− 1 applied for 2 minutes, can effectively enhance shoot growth, secondary metabolite synthesis, and the shoot/root ratio in Brassicaceae plants.

Western corn rootworm resistance in maize persists in the absence of jasmonic acid.

Larva growth, survival, and development speed were not affected by the absence of jasmonic acid (JA) indicating that JA does not have a direct role in maize resistance to western corn rootworm. Jasmonic acid (JA) is a plant hormone that regulates multiple physiological processes including defense against herbivory by chewing insects. Previous research showed its importance for resistance to aboveground herbivory. While few studies have investigated the role of JA in resistance to belowground root-feeding herbivores, none has directly tested the role of JA in such resistance. In this study, we used an opr7opr8 double mutant to directly test the role of JA in resistance to western corn rootworm (Diabrotica virgifera virgifera, WCR), a devastating and specialist pest of maize. The opr7opr8 double mutant is deficient in JA accumulation as we found that it does not accumulate JA nor JA-Ile independently of exposure to WCR. We found no significant difference in growth (body mass), survival, and development of WCR larvae in response to JA deficiency, suggesting that disruption of JA biosynthesis does not impact resistance in maize roots to WCR. Additionally, we observed no significant effect on loss of root tissue caused by WCR associated with JA deficiency, while we found a reduction in shoot growth (mass) associated with WCR herbivory in the opr7opr8 mutant that was not observed in the wildtype. This suggested a role for JA in aboveground growth response to WCR herbivory rather than resistance to WCR.

Expansion of Pleioblastus amarus in tea plantations significantly enhances the appearance and nutritional composition of bamboo shoots but adversely affects palatability

The expansion of Pleioblastus amarus into tea plantations introduces environmental heterogeneity, significantly influencing the growth and quality of bamboo shoots. This study examined the effects of bamboo expansion on the appearance, nutrition, and palatability of bamboo shoots, utilizing partial least squares structural equation modeling (PLS-SEM) to identify key influencing factors. Results revealed that bamboo expansion increased shoot diameter, length, and fresh weight, enhancing overall size and edibility, particularly in the tea-bamboo mixed forest center zone (TBC), where appearance quality peaked. Nutritional analysis revealed substantial increases in protein, fat, starch, and vitamin C content after bamboo expansion, along with the improvements in amino acid score (AAS), essential amino acid index (EAAI), and nutritional index (NI), indicating elevated nutritional value. However, despite the rise in soluble sugars and flavor-enhancing amino acids, higher levels of total acids, oxalic acid, tannins, and cellulose diminished the palatability, notably in TBC site. PLS-SEM further indicated that while bamboo expansion positively influenced shoot appearance and nutrition, soil factors predominantly drove these changes and concurrently detracted from overall palatability. These findings provide a framework for enhancing bamboo shoot quality and optimizing management practices in tea plantation ecosystems.

The Effect of Selenium Sources and Rates on Cowpea Seed Quality

Selenium (Se) is a beneficial element for plants and is essential for human nutrition. In plants, it plays an important role in the formation of selenocysteine and selenomethionine and in the activation of hydrolytic enzymes, which can aid in seed germination and reduce abiotic stress during germination. The objective of this study was to evaluate the effects of the application of selenium sources and rates to the soil on the physiological quality of cowpea seeds. The experimental design was a randomized block with four replications and a factorial scheme (7 × 2). Two sources of Se (sodium selenate and sodium selenite) and seven rates (0, 2.5, 5, 10, 20, 40 and 60 g ha−1) were used. Physiological characterization was carried out by first counting of germination, germination, emergence, accelerated aging, cold testing, electrical conductivity, length and dry biomass of shoots and roots. Germination after accelerated aging increased with selenate, even at higher rates, whereas selenite provided benefits at lower rates. Selenation linearly increased germination after the cold test and linearly reduced electrolyte leakage as the Se rate increased. The soil application of Se is beneficial for cowpea seed quality. Compared with those treated with sodium selenite, cowpea plants treated with sodium selenate through the soil produce more vigorous seeds. The application of 10 g ha−1 Se in the form of sodium selenate provides seedlings with faster germination and root development and is an alternative for rapid stand establishment.

Plant growth promoting properties of Methylobacterium brachiatum B0021T and its influence on the growth and short-term thermal stress resistance of Lactuca sativa L

Abstract The paper describes the investigation of the effect of inoculation by Methylobacterium brachiatum B0021T on both the growth lettuce plants and their resistance to short-term thermal stress which was made for the first time. The ability of strain B0021T to synthesize indole derivatives, siderophores, to solubilize insoluble phosphates was revealed. It was shown that inoculation of lettuce plants by strain B0021T improved of shoot growth and development, formation of the root system. It had a positive effect on the work of the photosynthetic apparatus, and also increased resistance to short-term temperature stress in vegetation experiments. The obtained results indicate the potential of using the studied strain to improve the yield of agricultural crops, as well as to protect plants from unfavorable environmental conditions.

Rooting for Success: The Role of Microorganisms in Promoting Growth and Resilience in Black Alder Seedlings.

Polycyclic aromatic hydrocarbons (PAHs) pose a global environmental risk, impacting human health. Enhancing phytoremediation with microbial-plant interactions could help mitigate these pollutants. However, tree responses to PAHs are unclear, necessitating controlled studies before field experiments. This study examined how PAH-degrading microbes affect black alder (Alnus glutinosa L.) seedlings grown hydroponically, hypothesizing that specific microbes improve growth and stress tolerance. Two half-sib families (41-65-7 K, 13-99-1 K) were inoculated with Rhodotorula sphaerocarpa (R.s.), Pseudomonas putida (P.p.), and Sphingobium yanoikuyae (S.y.). Results showed family-dependent and microbe-specific effects, with family 41-65-7 K showing enhanced shoot growth (threefold increase by R.s.) and higher carotenoid levels. Antioxidant enzyme activities varied: R.s. elevated superoxide dismutase activity by 4.8-fold in 13-99-1 K, while catalase activity increased but decreased in 41-65-7 K. Principal component analysis revealed distinct phytochemical clustering based on microbial treatment, highlighting genotype-specific modulations. Each microorganism had unique plant growth-promoting traits, with P.p. producing the most phytohormone and S.y. fixing nitrogen. These findings support targeted microbial inoculation for effective remediation of PAH-contaminated environments.

Enhancing phosphorus-solubilizing microorganism potential for alleviating plant phosphorus limitation through amino acid co-application

Phosphorus-solubilizing microorganisms (PSMs) are recognized as a sustainable ecological strategy to mitigate plant phosphorus (P) limitation. However, their efficacy in real-world production scenarios is not as consistent as observed in controlled laboratory conditions. To deepen our comprehension of PSMs in mitigating plant P limitation and evaluate the efficacy of combined amino acids (AA) and PSMs application in optimizing plant nutritional environments, we conducted a study, aiming to preliminary delineate the model of plant-microbe-soil interactions facilitated by this joint approach. Phyllostachys edulis seedlings were cultivated in phosphorus-limited soil with or without AA and PSMs application. We assessed treatment impacts on plant growth and soil nutrient conditions through plant biomass, root morphology, tissue nitrogen (N) and P content, soil N and P contents, rhizosphere microbial communities, and soil enzyme activities. Application of AA and PSMs significantly enhanced shoot growth of P. edulis seedlings, reduced root ratio, modified root morphology, increased N and P content in plant tissues, facilitated conversion of soil insoluble P to active forms, and raised total soil N, alkali-hydrolysable N, ammonium N, and nitrate content. Moreover, it influenced the structure and function of the soil microbial community. Notably, soil enzyme activities under the combined application exhibited distinctions from individual applications, demonstrating greater similarity to the treatment without AA and PSMs, which received no additional amendments. Our findings underscored the significant positive impact of the combined AA and PSMs application on P. edulis seedling growth, improving soil nutrient status, enriching plant growth-promoting rhizobacteria, and reducing soil diseases. However, plant-soil-microbe interactions induced by the combined application might differ from those observed with individual applications, necessitating further experimentation for a comprehensive understanding.

From intercropping to monocropping: the effects of Pseudomonas strain to facilitate nutrient efficiency in peanut and soil

As an oilseed crop, the yield and quality of peanuts are severely constrained by nutrient deficiencies, particularly in calcareous soils in northern China. Maize-peanut intercropping is an effective strategy to enhance mineral nutrient efficiency in peanuts via plant-microbe interaction, but the underlying mechanisms remain elusive. Here, we conducted experiments using a Pseudomonas strain (Pse.IP6) with diverse beneficial characteristics, which was isolated from the rhizosphere of intercropped peanuts. Additionally, Pse.IP6 exhibits high phylogenetic similarity with the Amplicon Sequence Variants 48 (ASV48) which belongs to Pseudomonas and is positively correlated with Fe in plants and soil in intercropping. To confirm the plant growth-promoting potential of Pse.IP6 and its role in intercropping advantage, we constructed pot experiments. Results revealed that Pse.IP6 promoted shoot growth and root development, as well significantly enhanced SPAD value, net photosynthetic rate, stomatal conductance, and transpiration rate of peanut leaves. Moreover, the application of Pse.IP6 resulted in a notable accumulation of nitrogen (N), phosphorus (P), and potassium (K) in shoot and active iron (Fe) in leaves, accompanied by an increased K-N ratio. The primary reason for the nutrient promotion is the enhancement of the bioavailability of nitrate, ammonium, P, K, and Fe in the rhizosphere. Collectively, our findings demonstrate that Pse.IP6, enriched in intercropping peanut, is a plant growth-promoting bacteria, represented by transferring the intercropping advantage on nutrients activation to monocropping peanuts. Our results offer insights into plant-rhizobacteria interaction mechanisms and therefore provide a rhizobacteria-based pathway to improve nutrient efficiency and productivity of crops.

Photosynthetic Daily Light Integral Effects on Rooting and Vegetative Growth of Cuttings of Six Foliage Plants

Recently, millennials, social media, and the COVID-19 pandemic have spurred the demand for indoor foliage plants. Between 2019 and 2022, the wholesale value of foliage plants in the United States increased by 45% to $1 billion. However, few propagation protocols are available for greenhouse growers in temperate climates. Additionally, the mechanisms by which shade and succulent crops photosynthesize, root, and accumulate biomass in response to environmental parameters are largely unknown. Therefore, the objective of this study was to determine the photosynthetic daily light integral (DLI) that leads to uniform, high-quality, and rapid rooting of foliage crop cuttings. Vegetative shoot tip cuttings of Curio peregrinus ‘String of Thai Dolphins’ (dolphin plant), Curio rowleyanus ‘String of Pearls’ (string-of-pearls), Curio herreianus ‘String of Pearls Big Bead’ (string-of-pearls big bead), Peperomia obtusifolia ‘Emerald Isle’ (baby rubber plant), Peperomia ferreyrae ‘Happy Bean’ (pincushion peperomia), and Sedum makinoi ‘Tornado’ (stonecrop) were excised from stock plants. Then, the cuttings were inserted in plug trays filled with a propagation medium consisting of a 1:1 (v/v) of half 70% peatmoss, 21% perlite, and 9% vermiculite and half medium perlite. Then, the cuttings were placed under a DLI of approximately 5 mol·m−2·d−1 for 7 days of callus induction, and subsequently under shading of 70% (2.9–3.4 mol·m−2·d−1), 50% (4.5–6.5 mol·m−2·d−1), 30% (7.8–11.2 mol·m−2·d−1), or 0% (10.2–16.4 mol·m−2·d−1), resulting in DLIs ranging from 2.9 to 16.4 mol·m−2·d−1. After 21 days, the stem length of stonecrop and pincushion peperomia rooted cuttings decreased as the DLI increased from 2.9 to 16.4 mol·m−2·d−1. However, the stem length of string-of-pearls and string-of-pearls big beads rooted cuttings increased after 28 days as the DLI increased from 2.9 to 16.4 mol·m−2·d−1. As the DLI increased from 2.9 to 16.4 mol·m−2·d−1, the shoot dry mass of dolphin plant and baby rubber plant significantly increased by 168% and 189%, respectively. Additionally, the root dry mass of dolphin plant and baby rubber plant significantly increased by 376% and 50%, respectively. The quality index of all five cultivars was greatest under DLIs of 10.2 to 16.4 mol·m−2·d−1, with the exception of pincushion peperomia, which had the highest quality index under DLIs of 2.9 to 4.6 mol·m−2·d−1. Our findings indicate that higher DLIs benefit shoot growth during rooting, but not necessarily root biomass accumulation of all genera investigated.

F1 Hybrid Seed Can Enhance Cannabis Crop Uniformity and Yield

Cannabis (Cannabis sativa) growers seek greater crop uniformity and yield; however, use of vegetatively propagated plants has several drawbacks. There is increased interest in F1 hybrid seed, especially for flower production. Plant growth and performance of inbred lines of the cultivars Wife (WF) and Wilhelmina (WH), produced from one to four rounds of selfing (S1 to S4), and three F1 hybrid lines (WF S1 × WH S1, WF S2 × WH S2, and WF S3 × WH S3) were evaluated. As selfing increased from S1 to S4, within line plant variation did not change substantially for most measures for WF, but variation progressively decreased for plant height, total shoot length and plant dry weight for WH. S4 plants of WH were uniformly diminutive and likely exhibited inbreeding depression. F1 hybrids between WF and WH were larger than WH plants for all measures because WH is photoperiod insensitive (autoflowering) and dwarf. Compared with WF self-lines, F1 WF × WH hybrid lines exhibited greater uniformity, plant dry weight, flower dry weight, and percent cannabidiol and tetrahydrocannabinol. F1 WF × WH hybrid plants were able to achieve similar height and shoot growth to WF self-lines, even though they had a dwarf parent in WH. It is likely that heterosis is responsible for the growth enhancements observed in the F1 WF × WH hybrids. These findings indicate that F1 hybridization can produce uniform, stable, and high-yielding cannabis plants from seed.

The phenology of flowering in Spiranthes sinensis s.s.

The native Spiranthes sinensis s.s. of Taiwan is an emerging ornamental potted orchid. This study aims to understand the conditions for floral differentiation and life cycle to facilitate artificial cultivation and commercial production of S. sinensis. Every August, new leaves appeared from the dwarf stem, during which the old roots acted as a nutrient source, providing the energy needed for the initial foliation phase. In November, the apical bud enters the floral initiation. In January, the apical bud began to transform into the primary inflorescence of the plant, while the lateral bud apical meristem began to differentiate into floral meristem. The plant produced a main spike in February, followed by the lateral bud inflorescences; the plant bloomed from March to May. Changes in sugar and starch contents were associated with inflorescence development. A higher soluble sugar level was noted in the roots and stems from January to April at the time of anthesis. Starch began to accumulate in the roots from February to August. The growth cycle restarted in August every year with new shoot formation, with the roots providing the initial nutrients for shoot growth to restart a new growing cycle. The influence of temperature changes on inflorescence development and flowering is discussed.

Comparative study of the effect of moderate and strong sodium chloride salinization on growth and photosynthetic apparatus of cultivated cereals

In a controlled environment, the effect of moderate (100 mM) and strong (200 mM) sodium chloride salinity on seed germination, seedling growth and the state of the photosynthetic apparatus (PSA) of barley (Hordeum vulgare L.) varieties Nur and wheat (Triticum aestivum L.) varieties Zlata was studied. It was found that with moderate salinization, the seeds of both species successfully germinated, but the growth of shoots and the accumulation of aboveground biomass were inhibited, which was partly due to a slowdown in the rate of photosynthesis. With strong salinity, distinct interspecific differences were observed in the response of plants. In particular, the number of germinated seeds decreased in barley, while in wheat it remained at the control level. In barley, shoot growth was inhibited to a greater extent, whereas in wheat, the accumulation of aboveground biomass was. The content of pigments in barley plants decreased, and the content of wheat increased. At the same time, stomatal conductivity decreased in both species and the rate of photosynthesis slowed down. It is concluded that based on the energy of germination and germination of seeds, it is possible to determine the salt resistance of species only to a high level of salinity (200 mM NaCl). Morphometric indicators of shoot growth make it possible to assess the resistance of plants to salinity already at lower salt concentrations (100 mM NaCl). For a more accurate comparative assessment of the salt resistance of species (varieties, varietals, genotypes) of cereals, not one, but several indicators should be used, reflecting not only the growth potential of plants, but also photosynthetic activity.

Invertase of the cell wall controls the growth of both the apical and vegetative organs of the tomato

Researchers have intensively studied how external factors like temperature, humidity, soil structure, and fertilizer affect tomato plant growth. However, little is known about how internal factors, particularly cell wall invertase, affect plant growth. This study aims to determine how the activity of the cell wall invertase enzyme regulates the apical and vegetative growth of plants. The study utilized four tomato plants, consisting of two transgenic and two wild-type plants. The transgenic plants in one set exhibit lower levels of the cell wall invertase, known as TLINA. Another set of transgenic plants, known as TINHI, exhibited higher levels of the cell wall invertase. We named both wild types of plants, WLINA and WINHI, respectively, and used them as the control plant. The study's results revealed that the transgenic plants (TLINA) ceased their apical shoot growth, leading to the growth of an axial shoot to take the place of the apical shoot. t. Also, the TLINA plants grew lower than wild-type plants. Interestingly, the vegetative organs of TINHI plants grew higher than both wild types and TLINA plants. This evidence suggested that cell wall invertase regulates the apical and vegetative organs of plants.

Arbuscular mycorrhizal fungi improve morphological and yield performance of Eragrostis tef genotypes in Tigray, Ethiopia

Arbuscular mycorrhizal fungi (AMF) form beneficial partnerships with most plant species, helping to improve crop resilience in tough environmental conditions. This paper analyzed how different genotypes responded to AMF inoculation, focusing on root colonization percentage (RCP) and the impact of AMF on above-ground agronomic traits. However, RCP alone may not fully explain genotype variation, and AMF effects cannot be judged solely on above-ground traits. This research aims to explore the variation in ninety tef genotypes under AMF conditions and assess how AMF and genotypes affect root and shoot morphology traits. Genotypes were sorted into six cluster groups, showing varied responsiveness to AMF, with RCP ranging from 25.03 to 72.29%. Despite similar RCP, variations in morphological traits were observed, and groups with lower RCP exhibited important traits not found in those with higher RCP, indicating RCP alone cannot indicate genotype variability. Wider Mahalanobis distance (D2) between clusters IV and VI, I and VI, and V and VI were crucial for developing different varieties and advancing root traits through hybridization. Among the tested genotypes, Wehni and Tsaeda zezew, followed by Gureaza, exhibited higher scores for plant height (PH), panicle length (PL), shoot biomass yield (SBY), root length (RL), and specific root length (SRL) compared to Simada. However, Wehni, Tsaeda zezew, and Gureaza showed similar results for days to maturity (DM), grain yield (GY), harvest index (HI), root dry weight (RDW), and root depth distribution (RDD) but differed from Simada genotype. Moreover, the inoculated Wehni genotype increased in days to panicle emergence (DPE) by 72%, DM by 84.11%, PH by 73.93%, PL by 73.68%, SBY by 144.17%, GY by 254.58%, HI by 133.33%, RL by 74.16%, RDW by 216.92%, SRL by 220%, and RDD by 93.28% as compared to the non-inoculated Simada. Improved performance of inoculated genotypes despite genotype variability could be because AMF enhances nutrient and water uptake by increasing root and shoot growth and the inherent growth strategy of the genotypes. Small-seeded crops planted shallowly benefit from AMF, which promotes deeper root growth for better nutrient and water uptake.

Unveiling the ecological dominance of button mangrove (Conocarpus erectus L.) through microstructural and functional traits modifications across heterogenic environmental conditions

BackgroundThe button mangrove (Conocarpus erectus L.) is regarded as a peripheral species within mangrove communities. This particular species has the ability to thrive in regions that are arid or semiarid, where there is limited availability of nutrients. This study provides evidence of the ecological dominance of Conocarpus erectus across various habitats, highlighting its adaptability and success throughout the country of Pakistan. We collected twelve populations from four distinct ecological regions, including artificial forest plantations, agricultural fields, roadsides, and wastelands, offering a comprehensive assessment of C. erectus adaptability across diverse environmental contexts.ResultsForest plantation populations exhibited impressive shoot growth and moderate root lengths, with plants generally tall and well-weighted. Physiologically, they had moderate chlorophyll content and low carotenoid levels, with a balanced chlorophyll a/b ratio, indicating stable photosynthetic activity. Anatomically, these populations had thicker epidermal and cortical root layers but smaller vascular bundles and phloem regions. Stem and leaf structures were generally moderate in size, with thicker midribs and cortical layers in the leaves. Agricultural field populations showed robust shoot and root systems with balanced fresh and dry biomass. They exhibited high chlorophyll and carotenoid levels, indicating strong photosynthetic capacity. Root and stem anatomy revealed larger root areas, thicker cortex, and wide vascular bundles, reflecting enhanced structural development. Leaves from these populations had moderate midrib and cortical thickness, with larger stomatal areas, promoting efficient gas exchange. Roadside populations displayed deeper roots and reduced biomass production. These populations adapted to environmental stress through leaf expansion, with high leaf numbers and areas. Physiologically, populations had high chlorophyll content, with a high chlorophyll a/b ratio. Root and stem anatomy showed compact structures with smaller vascular bundles, indicating adaptation to harsher conditions. Leaf anatomy was moderate, with smaller vascular bundles and reduced water transport capacity. Wasteland populations exhibited poor growth and high shoot biomass despite small leaves. Physiologically, these populations had the highest total soluble protein and proline contents, reflecting stress adaptation. Anatomically, root and stem structures were variable, with some populations showing reduced cortical cell areas and smaller vascular bundles, indicating limited resource transport. Leaf structures had thicker lamina, thinner epidermal layers, and lower stomatal densities, reflecting adaptation to nutrient-poor soils.ConclusionThis study reveals the adaptability and thriving potential of Conocarpus erectus across varied habitats, providing key insights into its resilience and survival strategies. Understanding these adaptive traits can support habitat restoration, conservation planning, and improve species management in diverse environmental conditions, especially in response to climate change and habitat degradation.

Endophytic bacterial community dynamics in sweet cherry in vitro shoot culture and their role in shoot adaptation after cryopreservation

BackgroundIn vitro cultivation and cryopreservation techniques are essential tools for genetic diversity conservation and pathogen-free plant propagation of horticultural crops. The optimisation of cryopreservation protocols typically focuses on minimising the negative effects of pretreatment with cryoprotectors (CPs), cryogenic freezing (CF) treatment, and recovery procedures on explants. However, the impact of in vitro and CF techniques on plant-associated microbiota remains poorly understood, and their potential to improve plant adaptation after cryopreservation is underexplored. The aim of the present study was to investigate in vitro shoot culture and cryopreservation-induced changes in the endophytic bacterial diversity of two sweet cherry cultivars and to assess the potential of an inoculum of bacterial isolates to improve the growth of shoot culture after CF.ResultsCultivars ‘Sunburst’ and ‘Mindaugė’ showed different responses to cold hardening preconditioning as well as different survival and regrowth rates after cryopreservation. Metataxonomic analysis revealed variation in the abundance and taxonomic composition of bacteria assigned to 35 families in samples of field-grown tree leaves, dormant buds, and in vitro shoot culture before and after CF treatment. Bacillaceae and Enterobacteriaceae bacteria were predominant in the leaf samples of both cultivars. For ‘Sunburst’, Pseudomonadaceae and Sphingomonadaceae bacteria were dominant in dormant buds and in vitro shoots, respectively, while Burkholderiaceae was largely predominant in the shoots following CF treatment. Conversely, ‘Mindaugė’ tissues exhibited more consistent colonisation by Bacillaceae and Enterobacteriaceae across the experimental groups, except for in vitro shoots where Mycobacteriaceae prevailed. A pure bacterial isolate inoculum was applied to the ‘Mindaugė’ shoot culture to counter the CF treatment-induced suppression of shoot growth (~ 40%). Cocultivation with Brevibacterium sp. S1-2, Bacillus cereus S1-3, or B. toyonensis Nt18 increased the shoot leaf area from 48 to 75%.ConclusionsThis study revealed that endophytic bacterial diversity is significantly reduced under in vitro conditions, often leading to a genotype-specific increase in the abundance and dominance of bacteria attributed to a single bacterial family. Moreover, shoot cocultivation with endophytic bacterial isolates has potential for improving the recovery of in vitro shoots after cryopreservation.

Allelopathic effects of leaf extracts of Eucalyptus camaldulensis Dehnh. on morphological, physiological, and yield traits of Ethiopian wheat (Triticum durum L.) cultivars

Allelochemicals released into the soil from the leaves of eucalyptus species affect the growth and physiology of various crops. This study aimed to evaluate the allelopathic effects of aqueous and methanolic leaf extracts from Eucalyptus camaldulensis on three Ethiopian wheat cultivars (Assasa, Mukiye and Ude) of Triticum durum L. It was conducted as a pot experiment, and it utilized four concentrations of the extracts (Control (0%), 10%, 15%, and 20%) in a completely randomized design with three replicates. Results indicated that both extracts inhibited plant growth, biomass, and yield, with the methanolic extract showing stronger inhibitory effects. For instance, a concentration of 20% methanolic leaf extracts decreased chlorophyll fluorescence in the Assasa, Ude, and Mukiye cultivars by 53.97%, 36.36%, and 36.51%, respectively. The growth of both shoots and roots in Assasa, Ude, and Mukiye was significantly reduced at higher concentrations. Increasing concentrations of the extracts led to greater reductions in seedling traits and overall crop yield, with significant impacts observed (p ≤ 0.05). The findings suggest that eucalyptus should not be planted on agricultural land due to its negative impact on crop productivity.

Protein Phosphatase PP2C19 Controls Hypocotyl Phototropism Through the Phosphorylation Modification of NPH3 in Arabidopsis.

Plants exhibit shoot growth in the direction of the light source to facilitate photosynthesis, known as positive phototropism. In Arabidopsis hypocotyl phototropism, it is thought that a gradient of the signal intensity of the blue light photoreceptor phototropin1 (phot1) between the light-irradiated and shaded sides leads to the differential growth of hypocotyls. The intensity of phot1 signal is regulated not only by the protein kinase activity of phot1 but also by the phosphorylation status of the NONPHOTOTROPIC HYPOCOTYL3 (NPH3) protein, which has a dark form and a blue light form of the phosphorylation modification. Previous studies have shown that phot1 drives the forward reaction from the dark form to the blue light form of NPH3. However, the molecular mechanism underlying the reverse reaction remains unknown. Here, we show that protein phosphatase PP2C19 controls the reverse reaction that converts the blue light form of NPH3 to the dark form of NPH3. The PP2C19 protein possesses the PP2C domain, two cNMP-binding domains, and the protein kinase domain. Similar to phot1 and NPH3, PP2C19 localizes to the plasma membrane, and its PP2C domain is necessary and sufficient for PP2C19 function in hypocotyl phototropism. The pp2c19 mutants show abnormalities in second positive hypocotyl phototropism with a delay in the reverse reaction of NPH3 phosphorylation modification. The present study suggests that continuous blue light irradiation induces an equilibrium state of the reversible reaction of NPH3 phosphorylation, which acts as a phot1 signaling gradient with phot1 kinase activity to induce the second positive phototropism.

Postharvest pruning as a strategy to decrease shoot vigor and drying in a high-density pecan orchard

High-density pecan orchards may improve production and mitigate shading issues with the use of pruning. The period in which it is carried out may influence shoot vigor, branch drying, fructification and fruit quality. This study aimed at evaluating vegetative growth, production and fruit quality by conducting hedge and central pruning in a high-density pecan orchard for two cycles. The cultivar Pitol 1 was subject to the following treatments, which were evaluated in two cycles: no pruning, postharvest hedge pruning, dry hedge pruning, postharvest central pruning and dry central pruning. Variables under analysis were shoot growth, dry branches, production efficiency and fruit quality. Postharvest pruning decreased vigor and, consequently, shoot growth. The number of dry branches decreased after central pruning in both pruning periods whereas hedge pruning did not mitigate the problem. Production and production efficiency just increased after pruning in the second cycle. Fruit borne by trees that were subject to postharvest pruning got heavier but only the ones borne by trees subject to central pruning got larger. Central pruning resulted in lighter and yellowish kernels. Postharvest pruning is an alternative solution to get less vigorous shoot in high-density pecan orchards and its response is similar to the one of the winter pruning regarding reduction in dry branches. Postharvest central pruning is the treatment that increases fruit quality more than the others, in terms of size and weight.