Daughter Plants Research Articles

Rhizobacterial consortium differently affects black leaf spot, physiological, morphological, and productive components in two generations of banana plants

Rhizobacteria's effects on commercial banana plants in different generations remain unclear. In the present field-level investigation, we evaluated the effect of three types (injection, edaphic, and foliar) of applications of a local rhizobacterial consortium on Black leaf spot (BLS), chlorophyll content, morphological components, and fruit production in two generations of commercial banana plants cv. Williams. The rhizobacteria-treated mother and daughter plants received one and two applications, respectively, while the untreated plants constituted the control group. Results of the present investigation indicated that the rhizobacteria differently affect the aerial tissues of different generations of banana plants. Regardless of how the rhizobacteria were applied, they reduced an average of 40 % the BLS incidence on leaves (P ≤ 0.0001) and increased an average 9 % the plant height and pseudostem circumference (P ≤ 0.0001 – P = 0.0475) of mother and daughter plants were observed. However, both morphological variables improved even more in daughter plants edaphically treated with rhizobacteria. Leaf pigments like chlorophyll B (P = 0.0262) and the total content (P = 0.0230) only increased an average of 40 % in daughter plants treated with rhizobacteria. Rhizobacteria edaphic application and injection improved bunch weight (P = 0.0048) and hands per bunch (P ≤ 0.0001) in mother plants. Meanwhile, the edaphic application significantly increased the bunch weight (P = 0.0031), hands per bunch (P = 0.0074), and rachis weight (P = 0.023) by 17% on average in edaphically and foliar-treated mother plants, while the finger length (P = 0.0064) increased by 5% on average. Generally, the morphological and productive components increased much more in daughter plants than in mother. These findings demonstrate the potential of edaphically and foliar rhizobacterial applications to enhance plant health and productivity, providing a sustainable management strategy for banana cultivation.

Agronomic potential of nine strawberry cultivars for two consecutive cycles in a greenhouse

The lack of information about strawberry cultivation for more than one production cycle ends up generating high costs for producers to acquire daughter plants to reestablish their crops. Therefore, aiming at technical alternatives for a transition to more sustainable crops, the objective of this work was to investigate whether strawberry cultivars grown in a greenhouse for two cycles differ in terms of yield potential and fruit chemical quality. The treatments were nine strawberry cultivars (‘Albion’, ‘Aromas’, ‘Camarosa’, ‘Camino Real’, ‘Fronteras’, ‘Merced’, ‘Monterey’, ‘Portola’, and ‘San Andreas’) and two production cycles (2019/2020 and 2020/2021), arranged in a randomized block design with six replications. The results showed that in the second cycle the ‘Aromas’, ‘Camarosa’, ‘Camino Real’, ‘Merced’, and ‘Monterey’ cultivars stood out in terms of the highest number of fruits produced. ‘Fronteras’ and ‘Merced’ had the highest total production of strawberries in the second cycle. ‘Merced’ and ‘Monterey’ produced the highest fruits in the first cycle and ‘Fronteras’ produced strawberries with the highest average fresh fruit mass in the second cycle. ‘Albion’ and ‘Camarosa’ stood out for the higher sugar content in the fruits produced. The least acidic and most flavorful strawberries were produced in the first cycle. In conclusion, strawberry cultivars grown in greenhouses for two cycles differ in terms of yield potential and chemical fruit quality. This study indicates that the nine cultivars can be grown for two consecutive cycles without compromising berry production.

Epigenomic and transcriptomic persistence of heat stress memory in strawberry (Fragaria vesca)

BackgroundIn plants, epigenetic stress memory has so far been found to be largely transient. Here, we wanted to assess the heritability of heat stress-induced epigenetic and transcriptomic changes following woodland strawberry (Fragaria vesca) reproduction. Strawberry is an ideal model to study epigenetic inheritance because it presents two modes of reproduction: sexual (self-pollinated plants) and asexual (clonally propagated plants named daughter plants). Taking advantage of this model, we investigated whether heat stress-induced DNA methylation changes can be transmitted via asexual reproduction.ResultsOur genome-wide study provides evidence for stress memory acquisition and maintenance in F. vesca. We found that specific DNA methylation marks or epimutations are stably transmitted over at least three asexual generations. Some of the epimutations were associated with transcriptional changes after heat stress.ConclusionOur findings show that the strawberry methylome and transcriptome respond with a high level of flexibility to heat stress. Notably, independent plants acquired the same epimutations and those were inherited by their asexual progenies. Overall, the asexual progenies can retain some information in the genome of past stresses encountered by their progenitors. This molecular memory, also documented at the transcriptional level, might be involved in functional plasticity and stress adaptation. Finally, these findings may contribute to novel breeding approaches for climate-ready plants.

Arbuscular Mycorrhizal Fungi, Ascophyllum nodosum, Trichoderma harzianum, and Their Combinations Influence the Phyllochron, Phenology, and Fruit Quality of Strawberry Plants

One biostrategy to boost the sustainability of strawberry cultivation is the application of biostimulants to the growing substrate. Here, we investigated whether the use of biostimulants and their combinations affects the strawberry plants’ phyllochron, phenology, and fruit quality. We tested the absence (control) and presence of biostimulants (arbuscular mycorrhizal fungi (AMF), Ascophyllum nodosum (AN), Trichoderma harzianum (TH), AMF + AN, AMF + TH, AN + TH, and AMF + AN + TH). The experimental design used was in completely randomized blocks (four replications). AMF was represented by a multi-species on-farm inoculant; A. nodosum was represented by the commercial product Acadian®; and T. harzianum was represented by the commercial product Trichodermil®. The leaf emission rate, the occurrence and duration of phenological stages, and fruit quality were assessed. The greatest precocity in terms of harvesting the first fruit was observed in plants grown with AMF + TH, which also had the lowest phyllochron (77.52 °C day·leaf−1). Those treated only with AMF were the latest (144.93 °C day·leaf−1). More flavorful fruits were produced by plants grown with AMF + TH. Plants inoculated with the AMF community, whether or not associated with A. nodosum and T. harzianum, had more than 94% mycorrhizal colonization. We conclude that AMF, A. nodosum, T. harzianum, and their combinations influence the phenology, phyllochron, and fruit quality of strawberry plants. In the growing conditions of the Brazilian subtropics, the AMF and T. harzianum combination shortens the strawberry cycle, from transplanting the daughter plants to harvesting the first fruit, and improves the fruit flavor.

Piriformospora indica Enhances Resistance to Fusarium wilt in Strawberry by Increasing the Activity of Superoxide Dismutase, Peroxidase, and Catalase, While Reducing the Content of Malondialdehyde in the Roots

Strawberry Fusarium wilt, mainly caused by Fusarium oxysoporum f. sp. Fragariae (Fof), seriously threatens the yield and quality of strawberry. Piriformospora indica is an endophytic fungus that can colonise the roots of a wide range of plants, promoting plant growth and enhancing plant resistance. Against this background, the positive effects of P. indica on the growth of the daughter plants of ‘Benihoppe’ strawberry (Fragaria × ananassa Duch.) under Fof stress were investigated in this study. The study began by examining the inhibitory effect of P. indica on Fof growth through dual culture on agar plates. Subsequently, a symbiotic system between P. indica and strawberry plantlets was established, and the impact of P. indica on Fusarium wilt resistance and related physiological and biochemical indexes of the plantlets were evaluated. The results indicate that fungus colonization with P. indica significantly enhances the growth indices of strawberries, including plant height, petiole length, petiole diameter, and leaf area. Additionally, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in the leaves of P. indica were increased, and the content of malondialdehyde (MDA) was decreased compared to those without colonization. Under the stress from Fof, the growth indexes of plant height, stem diameter, leaf area, petiole diameter, and root length of strawberry plants colonization with P. indica were significantly higher than those without colonization and the symptoms of wilting were relatively mild. The activities of SOD, POD, and CAT in roots and leaves of plants colonized with P. indica were significantly increased compared to those without colonization. Furthermore, the content of MDA in roots was decreased. These results suggested that P. indica could increase resistance to Fusarium wilt in strawberry by increasing the activity of antioxidant enzymes and reducing the content of MDA.

Ecologically Based Management of Pineapple Mealybug Wilt: Controlling Dysmicoccus brevipes Mealybug Populations with Salicylic Acid Analogs and Plant Extracts

Mealybug wilt of pineapple (MWP) is a destructive disease worldwide caused by a parasitic complex that includes Pineapple Mealybug Wilt-associated Viruses (PMWaVs) and mealybugs (Dysmicoccus brevipes), which concurrently act as vectors for these viruses. Reducing the mealybug population is key to managing MWP, which is achieved in intensive production systems through the use of insecticides. SA (salicylic acid), ASM (acibenzolar-S-methyl), BABA (β-aminobutyric acid), and MeSA (methyl salicylate) are key components of systemic acquired resistance (SAR), the defense mechanism of plants against biotrophic agents such as mealybugs. In this study, these compounds were applied either as pure chemicals and/or as a major constituent of plant extracts. Both the Hawaiian hybrid MD-2 and Queen Victoria tissue culture plants, as well as suckers used for vegetative propagation, were treated with these compounds by direct application on the soil of pineapple pots. Subsequently, five mealybugs were released on each plant or each daughter plant in case of a transgenerational experiment; then, after 45 days, the number of mealybugs was counted. Exogenous SA, ASM, and MeSA reduced the population of mealybugs by a minimum of 50% and up to 80%. These SAR-inducing treatments could be an interesting alternative for controlling mealybugs and are already used in other pathosystems. The SAR mechanisms behind this effect are yet to be confirmed by molecular and enzymatic markers. ASM and MeSA are promising treatments for pineapples using tissue culture plants or traditional shoots.

Seed tuber imprinting shapes the next-generation potato microbiome.

Potato seed tubers are colonized and inhabited by soil-borne microbes, that can affect the performance of the emerging daughter plant in the next season. In this study, we investigated the intergenerational inheritance of microbiota from seed tubers to next-season daughter plants under field condition by amplicon sequencing of bacterial and fungal microbiota associated with tubers and roots, and tracked the microbial transmission from different seed tuber compartments to sprouts. We observed that field of production and potato genotype significantly (P < 0.01) affected the composition of the seed tuber microbiome and that these differences persisted during winter storage of the seed tubers. Remarkably, when seed tubers from different production fields were planted in a single trial field, the microbiomes of daughter tubers and roots of the emerging plants could still be distinguished (P < 0.01) according to the production field of the seed tuber. Surprisingly, we found little vertical inheritance of field-unique microbes from the seed tuber to the daughter tubers and roots, constituting less than 0.2% of their respective microbial communities. However, under controlled conditions, around 98% of the sprout microbiome was found to originate from the seed tuber and had retained their field-specific patterns. The field of production shapes the microbiome of seed tubers, emerging potato plants and even the microbiome of newly formed daughter tubers. Different compartments of seed tubers harbor distinct microbiomes. Both bacteria and fungi on seed tubers have the potential of being vertically transmitted to the sprouts, and the sprout subsequently promotes proliferation of a select number of microbes from the seed tuber. Recognizing the role of plant microbiomes in plant health, the initial microbiome of seed tubers specifically or planting materials in general is an overlooked trait. Elucidating the relative importance of the initial microbiome and the mechanisms by which the origin of planting materials affect microbiome assembly will pave the way for the development of microbiome-based predictive models that may predict the quality of seed tuber lots, ultimately facilitating microbiome-improved potato cultivation.

Binucleate Rhizoctonia AG‐A causing black root rot of strawberry in Albania

AbstractStrawberry production in Albania is very important and growing rapidly, while data on strawberry diseases are lacking. In 2022, symptoms of leaf necrosis, root rot, and wilt were observed on strawberry plants of cultivars ‘Savana’, ‘Sabrina’, and ‘Fortuna’ in greenhouses near Vajkan, Fier, Albania. The disease incidence was estimated at 50%. Only isolates of Rhizoctonia spp. were obtained from symptomatic plants. The isolates formed fast‐growing, white colonies with binucleate, typically branching hyphae and no sclerotia, resembling Rhizoctonia AG‐A. BLAST analyses of the ITS rDNA of isolate RhizAl (accession number OR231136) revealed the highest nt homology of 99%–100% (100% query coverage) with binucleate Rhizoctonia AG‐A isolates, while the neighbour‐joining phylogenetic analyses confirmed the identification. The pathogenicity of the isolate RhizAl was demonstrated by inoculations of disease‐free strawberry daughter plants (cv. ‘Fortuna’) that developed mild wilting and leaf necrosis 45 days after inoculation while plants collapsed with root necrosis 60 days after inoculation. In this study, binucleate Rhizoctonia AG‐A was detected for the first time as a causal agent of black root rot of strawberries in Albania and in general, and studies on the general importance of Rhizoctonia spp. in different crops in Albania are needed.

Diversity and Potential of Undergrowth as Traditional Medicine in Sangtandung Village, North Walenrang sub district, Luwu

The use of undergrowth as medicine has been carried out by many people, especially traditional communities who live far from health services whose use has been passed down from generation to generation. Attention to traditional medicines has shown an increase, this is evident from the use of natural medicine in developed countries reaching 65% while it is estimated that there are 9,600 plant species that have been utilized by 400 various ethnic or ethnic groups in Indonesia. Therefore, this study aims to determine the potential of the undergrowth used as traditional medicine in Sangtandung Village, North Walenrang District, Luwu Regency. There are two stages in this research, namely for species diversity using the method of determining plots for collecting data on species diversity, while the potential for medicine use uses an interview method with respondents who have been determined using a purposive sampling method. Data analysis for species diversity used is an important value index analysis by calculating the values of density, relative density, frequency, relative frequency, while for the potential of undergrowth as medicine using quantitative descriptive analysis. The results showed that there were 18 types of undergrowth identified as potential as traditional medicine in Sangtandung Village and the embarrassed daughter plant (Mimosa pudica Lin) had the highest IVI. Of the total 18 types of undergrowth that have the potential to be used as traditional medicine, there are 9 types that have been used by the community as medicine and 9 types that have not been utilized by the people of Sangtandung Village. Among them are putrimalu (Mimosa pudica Lin), urang aring (Eclita prostrate), sidaguri ( Sida rhombifolia), pakis (Polypodiophyta), bayam duri (Amaranthus Spinosus), bayam malabar (Basella alba), cakar ayam (Selaginella doederleinii), meniran (Phyllanthus urinaria), and gelinggang (Cassia Alata). Generally, the leaves are used by boiling and drinking the boiled water to treat various diseases.

NEMATODES AND ROOT SYSTEM ARE AFFECTED BY RHIZOBACTERIAL CONSORTIUM IN THE THIRD GENERATION OF COMMERCIAL BANANA PLANTS

Rhizobacteria has shown promising results in managing nematodes and improving the root system of banana plants. However, their effects on commercial banana plants in different generations remain unclear. In this study performed under field experiment, we evaluated the effect of three types (injection, edaphic and foliar) of a local rhizobacterial consortium application on the system root, nematode populations, and their damage in the third-generation plants. Only mother and daughter plants were treated twice with the rhizobacteria. Plants not treated with rhizobacteria constituted the control treatment. Our results show that rhizobacteria affect different underground tissues and nematodes in third-generation banana plants. Helicotylenchus spp., Meloidogyne spp., Pratylenchus spp., Radopholus similis, and Rhabditis spp. were the nematodes found in banana roots. R. similis population and the damage in the root system of banana plants were reduced significantly by the rhizobacteria edaphic application. The application of rhizobacteria could be a sustainable management strategy over time to improve the root system and suppress nematodes, and their damage in commercial banana plants.

Adaptive Strategies Employed by Clonal Plants in Heterogeneous Patches

Heterogeneity is widespread in natural environments; as a result, connected clonal ramets often live in areas characterized by patches of different resources. Specifically, clonal plants are frequently affected by conditions of heterogeneous water stress. This raises the question of how clonal plants grow and reproduce in areas with patches of different resources. In this study, we investigated the adaptation mechanisms of clonal plants under heterogeneous environmental conditions. On the one hand, we bore in mind that phenotypic plasticity is abundantly exhibited in clonal plants. Clonal plants respond to water stress mainly through regulation of the size of individuals, the allocation of population biomass, and the number of daughter plants, as well as the extension ability and branching intensity of clonal organs, which directly affect reproduction and population stability in clonal plants. On the other hand, we also considered the physiological integration in clonal plants which has been shown in many studies. Ramets of clonal plants normally stay connected to each other through horizontal connectors (stolons or rhizomes). Communicated substances and resources such as water, mineral nutrition, photosynthetic products, and secondary metabolites are translocated between ramets; by such means, the plant relieves stress caused by heterogeneous patches. In this study, we sought to obtain scientific references to improve our understanding of how clonal plants in natural environments acclimate to stresses caused by soil heterogeneity.

Suppression of Strawberry Anthracnose by Paenibacillus polymyxa TP3 In Situ and from a Distance.

Strawberry is a popular fruit with valuable nutrition and an attractive fragrance, but its production and propagation are limited by various diseases, including anthracnose and gray mold. For disease management, biological control measures are environmentally friendly and good alternatives to fungicides to avoid crop losses, reduce carbon emissions, and improve food safety. In this study, Paenibacillus polymyxa TP3, which originated from the strawberry phyllosphere, was shown to antagonize the anthracnose fungal pathogen Colletotrichum siamense and reduce leaf symptoms on strawberry plants. Several mass spectra corresponding to fusaricidin were detected in the confrontation assay of P. polymyxa TP3 and C. siamense by image mass spectrometry. The transcription of fusA and fusG in the fusaricidin biosynthesis gene cluster increased while P. polymyxa TP3 was cultured in the medium containing the culture filtrate of C. siamense, as detected by reverse-transcription polymerase chain reaction, indicating the involvement of fusaricidins in P. polymyxa TP3 antagonism against the anthracnose pathogen. Further disease control assays demonstrated the time frame and spatial mode of P. polymyxa TP3-induced systemic resistance of strawberry against C. siamense. The transcript level of the marker gene FaPDF1.2 of the jasmonic acid pathway increased in strawberry leaves after drenching treatment with P. polymyxa TP3, and the callose deposition was enhanced by further flg22 treatment. In addition, P. polymyxa TP3 treatments of the strawberry mother plants reduced C. siamense infection in the daughter plants, which would be a potent feature for the application of P. polymyxa TP3 in strawberry nurseries and fields to reduce the impact of diseases, especially anthracnose.

Influence of 'Atlantic' and 'Dakota Pearl' Mother Plants Exposed to Sublethal Glyphosate and Dicamba on Daughter Plants

Influence of 'Atlantic' and 'Dakota Pearl' Mother Plants Exposed to Sublethal Glyphosate and Dicamba on Daughter Plants

Sporodochia Formed by Fusarium oxysporum f. sp. fragariae Produce Airborne Conidia and Are Ubiquitous on Diseased Strawberry Plants in California.

Sporodochia are dense masses of fungal hyphae bearing asexual conidia. For Fusarium oxysporum, sporodochia are known to produce airborne conidia and enhance the dissemination of this otherwise soilborne pathogen. Sporodochia are small and transient, and they are documented for only a few formae speciales of F. oxysporum. This study reports airborne conidia and sporodochia produced by F. oxysporum f. sp. fragariae, the cause of Fusarium wilt of strawberry, in the Monterey Bay region of California. Sporodochia were discovered in 21 of 24 Fusarium wilt-diseased fields surveyed for this study and were readily observed on most symptomatic plants in these fields. Only necrotic tissues bore sporodochia, and they were most frequently observed on petioles and peduncles. Sporodochia covered significantly greater lengths of peduncles than petioles, extending from the base of the plant toward the upper part of the canopy. A stolon hosted the longest stretch of sporodochial growth, found covering the stolon's entire 35-cm length and the base of the daughter plant. Macroconidia were produced by all sporodochia samples, and we did not find microconidia on any samples. An initial series of experiments confirmed the potential for conidia produced by sporodochia to disperse with wind over short distances. The prevalence of sporodochia producing airborne spores of F. oxysporum f. sp. fragariae has great importance for disease management and biosecurity. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

A native parrot as an invasive plant controller

Generalist psittacines (parrots) can adjust to anthropogenic ecosystems by taking advantage of novel opportunities therein, such as by feeding on introduced plant species (Wilson J Ornithol 2008; doi.org/10.1676/07-038.1). In the city of Ilha Solteira (within the state of São Paulo, Brazil), a native blue-and-yellow macaw (Ara ararauna) – shown here – consumes flower buds of the African tulip tree (Spathodea campanulata) to access the calyx water, which is rich in amino acids. Such behavior, considered a dietary innovation (Ornitol Neotrop 2015; doi.org/10.58843/ornneo.v26i2.27), is a case of florivory of a non-native plant by a native animal. Florivory diminishes plant fitness by decreasing, and even eliminating, the chances that fruits and seeds will form (New Phytol 2021; doi.org/10.1111/nph.17670). According to the IUCN's Global Invasive Species Database, the African tulip tree is ranked 88 out of “100 of the World's Worst Invasive Alien Species” (https://bit.ly/3ZvinOX). Outside of its native range in West Africa, the tree can degrade tropical ecosystems not only by altering habitat structure and ecological processes but also by reducing biodiversity (Anthr Sci 2022; doi.org/10.1007/s44177-021-00004-y). Notably, macaws’ florivory provides some degree of biological control, which could be high given that the birds en masse can consume more than 100 flower buds in a single feeding bout lasting only a few minutes. Indeed, since 2014 (when the macaws discovered this food resource), we have rarely observed nearby African tulip trees bearing fruit and thus seeds, thereby limiting daughter plant recruitment.

Morpho-horticultural potential of seven strawberry cultivars for two consecutive cycles

Maintaining plants for two consecutive cycles in strawberry cultivation makes it possible to reduce costs with the acquisition of daughter plants and allows fruit production throughout the year. Thus, the objective of this study was to investigate whether strawberry cultivars grown for two consecutive cycles in a greenhouse change their horticultural potential. The research was carried out in the municipality of Passo Fundo, State of Rio Grande do Sul, Brazil. We tested seven strawberry cultivars (classified as short days and neutral days in terms of flowering) in two production cycles. The cultivars morphology was characterized, and the fruit production and quality were evaluated. The morphological descriptor that most contributed to the divergence among cultivars corresponded to anthocyanin coloration of stipules. ‘Aromas’ stood out for the greater amount of fruit produced in both production cycles. In the first cycle ‘Albion’, ‘Camino Real’, and ‘Monterey’ produced fruits with the highest average fresh masses. Phenolic compounds of the fruits were superior in the second cycle of cultivation in relation to the first cycle. The total flavonoid content was higher in ‘Aromas’, ‘Camarosa’, ‘Camino Real’, and ‘Monterey’. ‘Camarosa’ and ‘San Andreas’ had the highest concentration of total polyphenols. The total antioxidant capacity was higher in ‘Aromas’ and ‘Camarosa’. It is concluded that strawberry cultivars conducted for two consecutive cycles in a greenhouse show variations in their horticultural potential. Producers who want to stagger their crops should choose ‘Aromas’ to obtain greater productive potential (in both cycles) and ‘Camarosa’ to meet the demanding consumer market in fruit quality.

Effects of drought stress treatment on phytochemical contents of strawberry varieties

Drought is nowadays a significant environmental factor limiting plant quality and production. Strawberry (Fragaria x ananassa) is among the most widely grown and consumed fruit species in the world, and it is also extremely sensitive to drought stress. We investigated the effect of mild drought stress (MDS) on phytochemical contents in the strawberry varieties (cv. Festival, Benicia and Monterey). We applied two irrigation regimes (control and MDS). A control irrigation regime was applied to the daughter plant for the first two weeks followed by applying fertigation at the end of the second week by allowing daily drainage fraction of 30%. In MDS regime, half of the water given in the control treatment was applied, and the drainage fraction was kept at around 15%. MDS resulted in an increased content of amino acids (Protein, l-alanin, l-Aspartic acid, l-methionin, l-Glutamic acid, Fenilalanin, Lizin, Histidin, Triozin, Glisin, Valin, Leucine, Threonine, Serin, Prolin and Arjinin) but just IsoLeucine rate was not increased. DS also showed increased contents of total phenolic and total anthocyanin but DPPH level decreased.

Soil saline-alkali heterogeneity is an important factor driving the spatial expansion of clonal plant in grassland

Soil salinity is well known heterogeneous and various within natural soil environment. In Songnen grassland of Northeast China, grazing aggravates the saline-alkali heterogeneity in soil habitat, which led to dominant clonal plant species forming a variety of adaptive strategies. However, based on the previous studies of morphological plasticity and clonal integration in clonal plants, there was a lack of mechanism research on the spatial expansion strategy of clonal plants population subjected to clipping in saline-alkali heterogeneity soil patches. To address this knowledge gap, we carried out an experiment by applying different clipping intensities (0%, 35%, 70% of the above-ground biomass removed) to explore the spatial expansion strategy and morphological plasticity of Leymus chinensis and their belowground rhizomes in different heterogeneous saline-alkali patches. We found that, clipping significantly decreased the plant average height and above-ground biomass in homogeneous patches, especially heavy clipping had a significant adverse impact on plant belowground (rhizome, fine root) biomass and leaf area. However, there was no significant difference in the biomass, average height, and leaf area among the clipping treatments in low saline-alkali heterogeneous patches. In addition, the number of leaves, daughter plants and rhizome internode buds were significantly affected by saline-alkali heterogeneity alone, and low saline-alkali heterogeneity had a positive effect on these parameters. Biomass accumulation and rhizome expansion were gradually inhibited by the increasing of clipping intensity in a homogeneous environment, but the inhibitory effect of clipping was not significant in saline-alkali patches soil. We concluded that L. chinensis can respond to grazing or mowing disturbance by increasing tiller and daughter-plant numbers in a saline-alkali heterogeneous environment. The saline-alkali patches promoted clonal plant population spatial expansion more than grazing or mowing disturbance did. This study emphasizes saline-alkali heterogeneity distribution patterns in grassland soil environment were the primary and important driving factor promoting the spatial expansion of L. chinensis.

Infection Dynamics of Potato Virus Y Isolate Combinations in Three Potato Cultivars.

The United States potato industry has recently experienced a strain shift; recombinant potato virus Y (PVY) strains (e.g., PVYNTN) have emerged as the predominant strains over the long dominant ordinary strain (PVYO), yet both are often found as single infections within the same field and as mixed infections within individual plants. To understand mixed infection dynamics in potato plants and in daughter tubers, three potato varieties varying for PVY resistance, 'Red Maria', 'CalWhite', and 'Pike', were mechanically inoculated either at the pre- or postflowering stage with all possible heterologous isolate combinations of two PVYO and two PVYNTN isolates. Virus titer was determined from leaves collected at different positions on the plant at different times, and tuber-borne infection was determined for two successive generations. PVYNTN accumulated to higher levels than PVYO at nearly all sampling time points in 'Pike' potato. However, both virus strains accumulated to similar amounts in 'Red Maria' and 'CalWhite' potato early in the infection when inoculated preflowering; however, PVYNTN dominated at later stages and in plants inoculated postflowering. Regardless of inoculation time, both virus strains were transmitted to daughter plants raised from the tubers for most isolate combinations. The relative titer of PVYNTN and PVYO isolates at the later stages of mother plant development was indicative of what was found in the daughter plants. Although virus titer differed among cultivars depending on their genetics and virus isolates, it did not change the strain outcome in tuber-borne infection in subsequent generations. Differential virus accumulation in these cultivars suggests isolate-specific resistance to PVY accumulation.

Caracterização morfológica de novos clones-elites de bananeira

Abstract The characterization of clones is a very important step in genetic certification programs, as it describes and recognizes the plant material at every stage of production, allowing the monitoring of genetic quality, improvement and conservation of the germplasm. The aim of this work was to morphologically characterize two elite banana clones. The experimental design applied was in randomized blocks, with four replications, with six plants per parcel. The treatments consisted of two elite banana clones, Prata Gorutuba R1 and Prata Gorutuba R2 and four commercial cultivars: Prata Gorutuba, Prata Ana, Grande Naine and BRS Princesa. The morphological characterization was carried out in the second production cycle (daughter plant), using 23 qualitative descriptors, visually evaluated, classified according to the instructions for carrying out the distinguishability, homogeneity and stability (DHS) tests of banana cultivars. The elite clones Prata Gorutuba R1 and R2 differed from the cultivars Grande Naine and BRS Princesa regarding the descriptors tapering of the pseudostem, predominant color of the pseudostem, intensity of anthocyanin coloration and color of the underside of the basal sheath. The descriptors made it possible to group elite clones into the Prata group, a group that predominates in crops in Brazil, with characteristics already widely accepted by the market.