Petioles Of Plants Research Articles

Genome-wide identification of R2R3-MYB transcription factors in Betula platyphylla and functional analysis of BpMYB95 in salt tolerance

The Myeloblastosis (MYB) transcription factor (TF) family is one of the largest transcription factor families in plants and plays an important role in various physiological processes. At present, there are few reports on birch (Betula platyphylla Suk.) of R2R3-MYB-TFs, and most BpMYBs still need to be characterized. In this study, 111 R2R3-MYB-TFs with conserved R2 and R3 MYB domains were identified. Phylogenetic tree analysis showed that the MYB family members of Arabidopsis thaliana and birch were divided into 23 and 21 subgroups, respectively. The latter exhibited an uneven distribution across 14 chromosomes. There were five tandem duplication events and 17 segmental duplication events between BpMYBs, and repeat events play an important role in the expansion of the family. In addition, the promoter region of MYBs was rich in various cis-acting elements, and MYB-TFs were involved in plant growth and development, light responses, biotic stress, and abiotic stress. RNA-sequencing (RNA-seq) and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) results revealed that most R2R3-MYB-TFs in birch responded to salt stress. In particular, the expression of BpMYBs in the S20 subfamily was significantly induced by salt, drought, abscisic acid, and methyl jasmonate stresses. Based on the weighted co-expression network analysis of physiological and RNA-seq data of birch under salt stress, a key MYB-TF BpMYB95 (BPChr12G24087), was identified in response to salt stress, and its expression level was induced by salt stress. BpMYB95 is a nuclear localization protein with transcriptional activation activity in yeast and overexpression of this gene significantly enhanced salt tolerance in Saccharomyces cerevisiae. The qRT-PCR and histochemical staining results showed that BpMYB95 exhibited the highest expression in the roots, young leaves, and petioles of birch plants. Overexpression of BpMYB95 significantly improved salt-induced browning and wilting symptoms in birch leaves and alleviated the degree of PSII photoinhibition caused by salt stress in birch seedlings. In conclusion, most R2R3-MYB-TFs found in birch were involved in the salt stress response mechanisms. Among these, BpMYB95 was a key regulatory factor that significantly enhanced salt tolerance in birch. The findings of this study provide valuable genetic resources for the development of salt-tolerant birch varieties.

Advancing tomato crop protection: Green leaf volatile-mediated defense mechanisms against Nesidiocoris tenuis plant damage

Although Nesidiocoris tenuis is highly effective as a biological control agent, it can also damage tomato plants due to its zoophytophagous behavior. When N. tenuis pierces the stems and petioles of tomato plants with its stylets, it triggers callose deposition and subsequent cell death, resulting in blocked nutrient transport, floral abortions, or wilting of tender shoots. Recently, it has been shown that exposure of tomato plants to the green leaf volatile (Z)-3-hexenyl propanoate [(Z)-3-HP] activates defensive mechanisms, including the regulation of genes involved in the synthesis and degradation of callose. In this study, conducted under greenhouse conditions, we tested the hypothesis that damage caused by N. tenuis could be reduced by exposing tomato plants to (Z)-3-HP through polymeric dispensers. Tomato plants exposed to (Z)-3-HP and non-exposed control plants were inoculated with N. tenuis. Nesidiocoris tenuis established in both groups with no significant differences between the two treatments. However, as hypothesized, the damage caused by N. tenuis was significantly lower in the plants exposed to (Z)-3-HP. Gene expression analysis of salicylic, jasmonic, and abscisic acids, along with histochemical staining methods, was used to compare the defensive responses of tomato plants infested solely with N. tenuis versus those infested with N. tenuis and exposed to (Z)-3-HP. Our findings confirm the influence of (Z)-3-HP exposure on differential defensive activation between treatments and reduced callose deposition in (Z)-3-HP-exposed plants. These results pave the way for improved management of N. tenuis by enhancing the plant's defenses based on inter-plant communication.

The Short Inflorescence Mutation in Diploid Strawberry Fragaria vesca Affects Inflorescence Architecture and Runner Elongation

Mutants are useful for determining the genes that underlie a given trait. This information is highly useful for developing molecular markers for breeding and is the foundational knowledge required for future genomic crop improvements. The dessert strawberry, Fragaria ×ananassa, is a valuable crop with high potential for increased use in controlled environment agriculture. The genome of the woodland strawberry Fragaria vesca is the dominant genome of the four diploid strawberry subgenomes that contribute to the octoploid F. ×ananassa genome. F. vesca is therefore a useful reference system for determining gene function and should be a useful source of gene diversity for breeding of F. ×ananassa. Chemical mutagenesis of the inbred F. vesca line H4 F7-3 resulted in one M2 line with a smaller stature overall and which produces flowers on very short peduncles close to the crown. This line was named short inflorescence (sin). The sin phenotype results from a single gene recessive mutation that is pleiotropic in that the mutation also affects internode lengths of runners as well as petiole elongation of sin plants. Microscopic characterization revealed that sin peduncles are most likely short because of a failure of cells to elongate. Inflorescences, runners, and petioles of sin plants were found to elongate in response to exogenous gibberellin, indicating that sin could be a gibberellin biosynthesis or transport mutant. A brief characterization of sin plants is presented to facilitate collaborative studies of the line.

Antibacterial and antioxidant activity of endophytic fungi extracts isolated from the petiole of sungkai plant (Peronema canescens)

Abstract. Oktiansyah R, Elfita, Widjajanti H, Salni, Setiawan A. 2023. Antibacterial and antioxidant activity of endophytic fungi extracts isolated from the petiole of sungkai plant (Peronema canescens). Biodiversitas 24: 6516-6526. Indonesia has a diverse number of medicinal plants that are very helpful in preventing infectious diseases. Sungkai (Peronema canescens) is a medicinal plant of the family Verbenaceae that is often used and found in Indonesia. Its leaves possessed antibacterial and antioxidant properties that boost immunity and lessen the signs of infectious disorders. This study explored the types of endophytic fungi found in sungkai petioles and examined their relationship to previously reported sungkai leaf endophytic fungal isolates and spectrum of compounds contained them. Endophytic fungal were isolated from fresh leaf petioles of host plants, and their morphological and molecular characteristics were determined. Endophytic fungal extracts were tested for antibacterial and antioxidant properties. Utilizing the paper disk diffusion technique, the antibacterial characteristics were ascertained, while the DPPH method was used to determine antioxidant activity. Molecular identification was carried out on the fungal isolate with the most potential, and chemical compounds were isolated using column chromatography. The structures of the compounds were determined using spectroscopy, including 1D and 2D NMR. Eight endophytic fungal isolates were obtained from sungkai leaf stalks (RA1-RA8) of various species of the genus Trichoderma. Differences in the diversity of endophytic fungi found in leaf stalks and endophytic fungi from leaves were identified. RA1 showed the strongest antibacterial and antioxidant activity and was molecularly identified as T. harzianum. Spectroscopic analysis showed that the pure compound contained within was 9-hydroxy-7-methylenebenzo[c]oxepin-3(7H)-one (1), which had never previously been found in sungkai plants and endophytic fungi. The antibacterial activity of Compound 1 is in the strong category (MIC = 64 µg/mL) but is not active as an antioxidant. In terms of producing medicinal ingredients from endophytic fungi, T. harzianum in extract form has more potential to be developed.

The Absence of Malvidin-3-Glucoside in Petiole Tissue Predicts Rare Red-Type Flower of Eastern Redbud (Cercis canadensis L.)

Eastern redbud, Cercis canadensis L., is a popular ornamental tree in the U.S. and has flower colors of purple-type, red-type, and white-type. Most redbuds cultivars have purple-type flowers. Red-types and white-types are much less common. These unusual flower colors have become an important trait for incorporation into novel redbud cultivars. Eastern redbud seedlings require 3–5 years before blooming, making flower color selection a slow and expensive process. The ability to select seedlings for flower color type would significantly increase the efficiency of the breeding process. Redbud flower color is dominated by anthocyanin content; leaf petioles often show visible pink to purple color, indicating the potential presence of anthocyanin. In this study, anthocyanin profiles of 14 cultivars and 25 progenies of ‘Appalachian Red’ (red-type) × ‘Oklahoma’ (purple-type) were determined using HPLC. The petiole anthocyanin profiles were strongly indicative of plant flower-color types. Both peonidin-3-glucoside and malvidin-3-glucoside were dominant in petioles from all purple-type plants. In contrast, malvidin-3-glucoside was absent from petioles of red-type plants, and neither peonidin-3-glucoside nor malvidin-3-glucoside was detected among white-type cultivars. These results indicate that the presence or absence of peonidin-3-glucoside and malvidin-3-glucoside in petioles can be a physiological marker for identifying redbud flower color types.

Rapid metabolite response in leaf blade and petiole as a marker for shade avoidance syndrome

BackgroundShade avoidance syndrome (SAS) commonly occurs in plants experiencing vegetative shade, causing morphological and physiological changes that are detrimental to plant health and consequently crop yield. As the effects of SAS on plants are irreversible, early detection of SAS in plants is critical for sustainable agriculture. However, conventional methods to assess SAS are restricted to observing for morphological changes and checking the expression of shade-induced genes after homogenization of plant tissues, which makes it difficult to detect SAS early.ResultsUsing the model plant Arabidopsis thaliana, we introduced the use of Raman spectroscopy to measure shade-induced changes of metabolites in vivo. Raman spectroscopy detected a decrease in carotenoid contents in leaf blades and petioles of plants with SAS, which were induced by low Red:Far-red light ratio or high density conditions. Moreover, by measuring the carotenoid Raman peaks, we were able to show that the reduction in carotenoid content under shade was mediated by phytochrome signaling. Carotenoid Raman peaks showed more remarkable response to SAS in petioles than leaf blades of plants, which greatly corresponded to their morphological response under shade or high plant density. Most importantly, carotenoid content decreased shortly after shade induction but before the occurrence of visible morphological changes. We demonstrated this finding to be similar in other plant species. Comprehensive testing of Brassica vegetables showed that carotenoid content decreased during SAS, in both shade and high density conditions. Likewise, carotenoid content responded quickly to shade, in a manner similar to Arabidopsis plants.ConclusionsIn various plant species tested in this study, quantification of carotenoid Raman peaks correlate to the severity of SAS. Moreover, short-term exposure to shade can induce the carotenoid Raman peaks to decrease. These findings highlight the carotenoid Raman peaks as a biomarker for early diagnosis of SAS in plants.

Correlations between lignin content and structural robustness in plants revealed by X-ray ptychography

Lignin is a heterogeneous aromatic polymer responsible for cell wall stiffness and protection from pathogen attack. However, lignin represents a bottleneck to biomass degradation due to its recalcitrance related to the natural cell wall resistance to release sugars for fermentation or further processing. A biological approach involving genetics and molecular biology was used to disrupt lignin pathway synthesis and decrease lignin deposition. Here, we imaged three-dimensional fragments of the petioles of wild type and C4H lignin mutant Arabidopsis thaliana plants by synchrotron cryo-ptychography. The three-dimensional images revealed the heterogeneity of vessels, parenchyma, and fibre cell wall morphologies, highlighting the relation between disturbed lignin deposition and vessel implosion (cell collapsing and obstruction of water flow). We introduce a new parameter to accurately define cell implosion conditions in plants, and we demonstrate how cryo-ptychographic X-ray computed tomography (cryo-PXCT) provides new insights for plant imaging in three dimensions to understand physiological processes.

An efficient low-cost xylem sap isolation method for bacterial wilt assays in tomato.

PremiseA portable, simple, yet efficient method was developed for the rapid extraction of xylem sap from the stems and petioles of tomato plants for diagnostic and quantification assays of the xylem‐colonizing wilt bacterium Ralstonia solanacearum.Methods and ResultsXylem saps were extracted from tomato stem sections using negative pressure generated from handheld needleless syringes. The samples were collected from plants grown under different soil moisture levels at four days after inoculation with the pathogen. Pipette tips were modified to serve as adapters for the stem sections. The quantification of the bacterial load in the extracted sap was performed by plating sap dilutions in Kelman's triphenyltetrazolium chloride (TTC) medium. Pathogen identity was further confirmed by performing a PCR using R. solanacearum‐specific primers.ConclusionsDue to its simplicity, portability, and thoroughness of extraction from predetermined tissue sizes, the method can potentially facilitate high‐throughput onsite sampling from a large number of samples in a short time, which cannot be achieved with other available techniques.

Performance of cabbage stem flea beetle larvae (Psylliodes chrysocephala) in brassicaceous plants and the effect of glucosinolate profiles

AbstractThe cabbage stem flea beetle (CSFB), Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae), is one of the most important pests in European winter oilseed rape production. Adult beetles feed on young leaves whereas larvae mine within the petioles and stems. Larval infestation can cause significant crop damage. In this study, the host quality for CSFB of four oilseed rape (Brassica napus L.) cultivars and seven other brassicaceous species with different glucosinolate (GSL) profiles was assessed under controlled conditions. Larval instar weights and mortality were measured after 14 and 21 days of feeding in the petioles of test plants. To study the impact of GSL on the performance of larvae, the GSL contents in petioles from non‐infested and infested plants were analysed before, and 21 days after, the start of larval infestation. Larval performance was not significantly different between the four cultivars of oilseed rape, but differed considerably among the other brassicaceous species tested. In comparison to the weight of larvae in the standard B. napus cv. Robust, the larval weight was higher in turnip rape (Brassica rapa L. var. silvestris) and significantly reduced in white mustard (Sinapis alba L.), oil radish (Raphanus sativa L. var. oleiformis), and cabbage (Brassica oleracea L. convar. capitata var. alba). The duration of larval development increased in white mustard and oilseed radish. The GSL profiles of the petioles showed little difference between non‐infested and infested plants of oilseed rape whereas the content of aliphatic GSL increased in the infested turnip rape plants. In contrast, the aliphatic and benzenic GSL decreased in infested Indian rape (B. rapa subsp. dichotoma Roxb.). Larval weight was not correlated with the total GSL content of plants, neither before infestation nor 21 days after. Larval weight was positively correlated with progoitrin and 4‐hydroxyglucobrassicin. White mustard, which provides inferior host quality for larval development, has the potential to introduce insect resistance into high‐yielding oilseed rape cultivars in breeding programmes.

First report of a ‘Candidatus Phytoplasma asteris‘‐related strain associated with Melia azedarach phyllody in India

Chinaberry tree (Melia azedarach), also known as bead tree and belonging to the family Meliaceae, is an important ethnomedicinal tree with a wide natural distribution (Ntalli et al., 3). Its roots, stem and leaves possess various medicinal properties and have applications in various types of medicine. Chinaberry trees showing phyllody-like symptoms and virescent flowers were observed in Narayangoan (Pune), Maharashtra, in April 2018. Samples of four plants with symptoms and four without symptoms (Figs. 1-2) were collected and tested to detect the presence of phytoplasmas and for further molecular characterisation. Total genomic DNA was isolated from petioles of both healthy and infected plants using a DNeasy Plant Mini Kit (Qiagen, Germany). PCR was performed using P1/P7 phytoplasma-specific universal primers followed by nested PCR with R16F2n/R16R2 primers (Deng & Hiruki, 1; Schneider et al., 4; Gundersen & Lee, 2). Bands of the expected size (c. 1.8 and 1.2 kb, respectively) were obtained in samples from all symptom-bearing plants but not in the symptomless ones. The 16Sr DNA sequence amplified from a representative sample from a symptomatic plant was deposited in GenBank (Accession No. MN830223). Sequence comparison by BLAST analysis showed the highest sequence identity with members of the 16SrI phytoplasma group (aster yellows), such as Cocos nucifera lethal wilt phytoplasma (KY814724), Sandal spike phytoplasma (MK627541), Phyllanthus emblica witches' broom phytoplasma (MK627538), Sugarcane white leaf phytoplasma (MK627531) and Santalum album phytoplasma (MG865436). Phylogenetic analysis (Fig. 3) using the neighbour-joining method (MEGA X software) showed that the Melia azedarach phytoplasma sequence clustered within group 16SrI, subgroup B. Virtual RFLP analysis using iPhyClassifier (Zhao et al., 5) further confirmed that the Melia azedarach phytoplasma sequence shares 99.8% identity with that of ‘Candidatus Phytoplasma asteris’ reference strain (M30790), and that the phytoplasma is a ‘Candidatus Phytoplasma asteris‘-related strain, belonging to the 16Sr group I, subgroup B. To our knowledge, this is the first report of ‘Candidatus Phytoplasma asteris’ (16SrI-B) affecting M. azedarach in India. This finding holds significant importance for future epidemiological studies since M. azedarach could be an alternate host for phytoplasma (16SrI-B group) which infects several important vegetable crops cultivated in the country.

Roles of Small-Molecule Compounds in Plant Adventitious Root Development.

Adventitious root (AR) is a kind of later root, which derives from stems and leaf petioles of plants. Many different kinds of small signaling molecules can transmit information between cells of multicellular organisms. It has been found that small molecules can be involved in many growth and development processes of plants, including stomatal movement, flowering, fruit ripening and developing, and AR formation. Therefore, this review focuses on discussing the functions and mechanisms of small signaling molecules in the adventitious rooting process. These compounds, such as nitric oxide (NO), hydrogen gas (H2), hydrogen sulfide (H2S), carbon monoxide (CO), methane (CH4), ethylene (ETH), and hydrogen peroxide (H2O2), can be involved in the induction of AR formation or development. This review also sums the crosstalk between these compounds. Besides, those signaling molecules can regulate the expressions of some genes during AR development, including cell division genes, auxin-related genes, and adventitious rooting-related genes. We conclude that these small-molecule compounds enhance adventitious rooting by regulating antioxidant, water balance, and photosynthetic systems as well as affecting transportation and distribution of auxin, and these compounds further conduct positive effects on horticultural plants under environmental stresses. Hence, the effect of these molecules in plant AR formation and development is definitely a hot issue to explore in the horticultural study now and in the future.

High-resolution computed tomography reveals dynamics of desiccation and rehydration in fern petioles of a desiccation-tolerant fern.

Desiccation-tolerant (DT) plants can dry past -100MPa and subsequently recover function upon rehydration. Vascular DT plants face the unique challenges of desiccating and rehydrating complex tissues without causing structural damage. However, these dynamics have not been studied in intact DT plants. We used high resolution micro-computed tomography (microCT), light microscopy, and fluorescence microscopy to characterize the dynamics of tissue desiccation and rehydration in petioles (stipes) of intact DT ferns. During desiccation, xylem conduits in stipes embolized before cellular dehydration of living tissues within the vascular cylinder. During resurrection, the chlorenchyma and phloem within the stipe vascular cylinder rehydrated before xylem refilling. We identified unique stipe traits that may facilitate desiccation and resurrection of the vascular system, including xylem conduits containing pectin (which may confer flexibility and wettability); chloroplasts within the vascular cylinder; and an endodermal layer impregnated with hydrophobic substances that impede apoplastic leakage while facilitating the upward flow of water within the vascular cylinder. Resurrection ferns are a novel system for studying extreme dehydration recovery and embolism repair in the petioles of intact plants. The unique anatomical traits identified here may contribute to the spatial and temporal dynamics of water movement observed during desiccation and resurrection.

Diamondback moth egg susceptibility to rainfall: effects of host plant and oviposition behavior

AbstractOviposition patterns of the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae), differ between common cabbage (Brassica oleracea L. var. capitata) and Chinese cabbage (Brassica rapa L. var. pekinensis) (Brassicaceae) host plants. This study shows that the moth prefers to oviposit on adaxial rather than abaxial leaf surfaces and petioles of both host plants. More eggs were laid in leaf veins than on leaf laminas of both host plants, especially in Chinese cabbage, where 94.6% of eggs were laid in veins. On Chinese cabbage, very few eggs were laid in clusters (≥2 eggs), whereas on common cabbage approximately 30% of eggs were laid in groups of 2 or more eggs. Removal of wax from common cabbage leaves dramatically increased the number of eggs laid singly on the leaf lamina of treated plants, suggesting that leaf waxes affect how eggs are distributed by ovipositing DBM. Eggs were most susceptible to removal by rainfall from the plant surface immediately (<1 h) after oviposition and when close to hatching (>72h old) whereas they were least susceptible 24 h after oviposition. Eggs laid on common cabbage plants were more susceptible to simulated rainfall than eggs laid on Chinese cabbage plants. On common cabbage plants, egg susceptibility to rainfall on different plant parts ranked adaxial leaf surfaces>petioles = abaxial leaf surfaces>stem, but there was no difference in egg susceptibility to rainfall on the various plant parts of Chinese cabbage. Furthermore, on common cabbage plants, eggs laid on both adaxial and abaxial leaf surfaces were afforded significant protection from the effects of rainfall by leaves higher in the plant canopy. On common cabbage plants, oviposition patterns reduce the potential impact of rainfall on eggs, possibly reducing the effect of this important abiotic mortality factor in the field.

Pest categorisation of Septoriamalagutii.

The Panel on Plant Health performed a pest categorisation of Septoria malagutii, the causal agent of annular leaf spot of potato, for the EU. The pest is a well‐defined fungal species and reliable methods exist for its detection and identification. S. malagutii is present in Bolivia, Ecuador, Peru and Venezuela. The pest is not known to occur in the EU and is listed as Septoria lycopersici var. malagutii in Annex IAI of Directive 2000/29/EC, meaning its introduction into the EU is prohibited. The major cultivated host is Solanum tuberosum (potato), but other Solanum species including wild solanaceous plants are also affected. All hosts and pathways of entry of the pest into the EU are currently regulated. Host availability and climate matching suggest that S. malagutii could establish in parts of the EU and further spread mainly by human‐assisted means. The pest affects leaves, stems and petioles of potato plants (but not the underground parts, including tubers) causing lesions, leaf necrosis and premature defoliation. In some infested areas, the disease has been reported to cause almost complete crop loss with favourable weather conditions and susceptible potato cultivars. The introduction of the pest into the EU would potentially cause impacts to potato production. The main uncertainties concern the host range, the maximum period the pest survives on host debris in soil, the maximum distance over which conidia of the pest could be dispersed by wind‐driven rain and the magnitude of potential impacts to the EU. S. malagutii meets all the criteria assessed by EFSA for consideration as potential Union quarantine pest. The criteria for considering S. malagutii as a potential Union regulated non‐quarantine pest are not met, since the pest is not known to occur in the EU.

Pest categorisation of Stagonosporopsisandigena.

The Panel on Plant Health performed a pest categorisation of Stagonosporopsis andigena, the causal agent of black blight of potato, for the EU. The pest is a well‐defined fungal species and reliable methods exist for its detection and identification. S. andigena is present in Bolivia and Peru. The pest is not known to occur in the EU and is listed in Annex IAI of Directive 2000/29/EC as Phoma andina, meaning its introduction into the EU is prohibited. The major cultivated host is Solanum tuberosum (potato); other tuber‐forming Solanum species and wild solanaceous plants are also affected. All hosts and pathways of entry of the pest into the EU are currently regulated. Host availability and climate matching suggest that S. andigena could establish in parts of the EU and further spread mainly by human‐assisted means. The pest affects leaves, stems and petioles of potato plants causing lesions and premature leaf drop but not the underground parts, including tubers. The disease causes yield reductions up to 80%, depending on the susceptibility of potato cultivars. Early application of fungicide sprays and cultivation of resistant potato cultivars are the most effective measures for disease management. The pest introduction in the EU would potentially cause impacts to potato production. The main uncertainties concern the host range, the maximum period the pest survives on host debris in soil, the maximum distance over which conidia of the pest could be dispersed by wind‐blown rain, and the magnitude of potential impacts to the EU. S. andigena meets all the criteria assessed by EFSA for consideration as potential Union quarantine pest. The criteria for considering S. andigena as a potential Union regulated non‐quarantine pest are not met, since the pest is not known to occur in the EU.

PECTOBACTERIUM CAROTOVORUM subsp. BRASILIENSE CAUSING PEPPER BLACK SPOT DISEASE IN CHINA

In 2015, pepper black spot disease became seriously prevalent in Guangdong Province, China. The stem and petioles of diseased plants were strewn with black, circular to oval and bulged spots. A bacterium was isolated from black spots on stem. The bacterium could cause same symptoms on pepper plants by sprinkling inoculation. 16S rDNA sequences of bacterium shared 99-100% identity with Pectobacterium carotovorum subsp. brasiliense strain 1033. The 322 bp specific fragment could be amplified from the five bacterial isolates using primers Br1f/L1r specific for P. carotovorum subsp. brasiliense. Characteristics of the bacterium were consistent with those of P. carotovorum subsp. brasiliense reported. Thus, the causal bacterium identified was P. carotovorum subsp. 2 brasiliense. To the best of our knowledge, this is the first report of pepper black spot disease caused by P. carotovorum subsp. brasiliense in China.

Effect of shade and level of fertilizer application on nutrient uptake and dry matter partitioning in cocoyam (Xanthosoma sagittifolium L.)

ABSTRACTThe effect of shade and fertilizer application on nutrient uptake and dry matter (DM) partitioning in cocoyam was evaluated by growing the plant under different levels of shade and fertilizer application at Forest and Horticultural Crops Research Centre, Kade, within a period of 9 months. The shade levels used were 80%, 70%, and 50% shade, and full sunlight exposure. The fertilizer rates used were 112 kg/ha nitrogen, phosphorus and potassium (NPK) (15-15-15 120 kg/ha NPK (15-15-15) in a form) of mineral fertilizer, 112 kg/ha NPK organic fertilizer and no fertilizer (control). The split-plot design was used with shade levels as the main plot factor and fertilizer levels as the sub plot factor. The interaction effect of shade and fertilizer had a significant effect (p ≤ 0.05) on DM of cocoyam leaves, petioles, corm, and cormels as well as nutrient accumulation in plant parts. Cocoyam leaves of plants grown under 50–70% shade stored significantly higher (p ≤ 0.05) quantities of nutrients (1.51 ppm of N, 6.61 ppm of P, and 53.10 ppm of K) and accumulated more DM (71.30 g) than leaves of plants grown under full sunlight exposure which accumulated 1.37 ppm of N, 4.31 ppm of P, 26.06 ppm of K, and 30.7 g DM, at the two rates of the chemical fertilizer application. Under full sunlight exposure, significantly higher amounts of DM were accumulated in the corms and cormels at mineral fertilizer level of 112 kg/ha. At mineral fertilizer rate of 120 kg/ha, nutrient accumulation was significantly higher (p ≤ 0.05) in the corm and cormels (1.72 ppm of N and 7.72 ppm of P) of plants grown under full sunlight exposure than those grown under 70% shade level (0.6 ppm of N and 2.94 ppm of P). Nitrogen and phosphorus accumulation was significant in the petioles of plants grown under the 70% shade level at fertilizer rate of 120 kg/ha. It is recommended that cocoyam be grown under 50–70% shade at a fertilizer rate of 112–120 kg/ha for leaf production and under full sunlight exposure at 112 kg/ha (NPK) for cormel production.

Dynamics of amino acid redistribution in the carnivorous Venus flytrap (Dionaea muscipula) after digestion of 13 C/15 N-labelled prey.

Amino acids represent an important component in the diet of the Venus flytrap (Dionaea muscipula), and supply plants with much needed nitrogen resources upon capture of insect prey. Little is known about the significance of prey-derived carbon backbones of amino acids for the success of Dionaea's carnivorous life-style. The present study aimed at characterizing the metabolic fate of 15 N and 13 C in amino acids acquired from double-labeled insect powder. We tracked changes in plant amino acid pools and their δ13 C- and δ15 N-signatures over a period of five weeks after feeding, as affected by contrasting feeding intensity and tissue type (i.e., fed and non-fed traps and attached petioles of Dionaea). Isotope signatures (i.e., δ13 C and δ15 N) of plant amino acid pools were strongly correlated, explaining 60% of observed variation. Residual variation was related to contrasting effects of tissue type, feeding intensity and elapsed time since feeding. Synthesis of nitrogen-rich transport compounds (i.e., amides) during peak time of prey digestion increased 15 N- relative to 13 C- abundances in amino acid pools. After completion of prey digestion, 13 C in amino acid pools was progressively exchanged for newly fixed 12 C. The latter process was most evident for non-fed traps and attached petioles of plants that had received ample insect powder. We argue that prey-derived amino acids contribute to respiratory energy gain and loss of 13 CO2 during conversion into transport compounds (i.e., 2days after feeding), and that amino-nitrogen helps boost photosynthetic carbon gain later on (i.e., 5weeks after feeding).

Variations in leaf functional traits among plant species grouped by growth and leaf types in Zhenjiang, China

Leaf functional traits are adaptations that enable plants to live under various environmental conditions. This study aims to determine the differences in leaf functional traits among plants grouped by growth habit, leaf life span, leaf lifestyle, leaf form, and origin. Specific leaf area (SLA) of perennial or evergreen species was lower than that of annual or deciduous species because longer-lived leaves of perennial or evergreen species require more investment in structural integrity and/or defense against disturbances, especially with any resource constraint. SLA of large individuals was lower than that of small individuals. The low SLA in large individuals can improve their response to changing light and water conditions because increasing plant height is advantageous for light competition, but it can also impose a cost in terms of structural support and water transport. Petioles of plants with compound leaves were significantly longer than those of simple leaves because branching is expensive in terms of gaining height. SLA of plants increased with increasing invasiveness accordingly, and SLA of invasive plants was higher than that of their native congeners because invasive plants should invest more biomass on leaf growth rather than leaf structures per unit area to achieve a higher growth rate. Overall, variation in leaf functional traits among different groups may play an adaptive role in the successful survival of plants under diverse environments because leaf functional traits can lead to pronounced effects on leaf function, especially the acquisition and use of light. Plant species with different growth and leaf traits balance resource acquisition and leaf construction to minimize trade-offs and achieve fitness advantages in their natural habitat.

Biochemical Characterization of Compatible Plant Virus Interaction: A Case Study with Bunchy Top Virus-Banana Host-Pathosystem

Environmental stresses of both biotic and abiotic nature produce characteristic changes in physiology and metabolic processes of higher plants (Miteva et al., 2005). Among these stresses, infection by the pathogens causes substantial alterations of biochemical changes leading to harmful effects on plant health. Banana cultivation is subjected to many natural calamities including pest and pathogen attacks which constitute the major production problem. Among plant diseases, viral diseases may cause considerable loss on production by retarding plant growth and reducing yield. Four viral diseases viz., Banana Bunchy Top Disease (BBTD) caused by Banana bunchy top virus (BBTV), Bract Mosaic Disease (BBrMD) caused by Banana bract mosaic virus (BBrMV), Banana Streak Disease (BSD) caused by different species of Banana streak virus (BSV) and banana mosaic or infectious chlorosis caused by Cucumber mosaic virus (CMV) occur in most of the banana growing regions of the world. Among banana viral diseases, Banana Bunchy Top Disease (BBTD) is one of the most destructive viral diseases in Tropical Asia, Pacific Indian Oceania (PIO) regions and Africa. Grand Nain, Virupakshi (Hill banana), Robusta, Nendran, Rasthali, Poovan, Ney Poovan, Monthan and Red Banana are severely affected by BBTD. There is no resistance gene source available in germplasm of bananas and plantains (Shekhawat et al., 2012). The BBTV affected plants show intermittent dark green dots, dash, streaks of variable length on leaf sheath, midrib, leaf veins and petioles of infected plants. Leaves produced are progressively shorter, brittle in texture, narrow and gives the appearance of bunchyness at the top leading to 100% yield loss (FAO., 2009). Plants have evolved various pre-existing physical and chemical barriers, as well as inducible defense responses that interfere with pathogen colonization (Jones and Dangl, 2006; Zhao et al., 2008; Vanitha et al., 2009). However, this requires comprehensive studies and understanding of the adaptive mechanisms and responses to BBTV infection in banana. Because viruses cannot be cultured in vitro, our knowledge about their interactions with host and changes on physiology, biochemistry and molecular biology of the host is limited. Moreover, a comprehensive report regarding biochemical alterations in banana plants infected by BBTV is still not clear. Therefore, the present investigation was conducted to find the quantitative estimations of physiological and biochemical parameters such as protein, pigment and carbohydrate contents, phenolic compounds, polyphenol oxidase (PPO), peroxidase (POX), catalase (CAT), ascorbate peroxidise (APX), guaiacol peroxidise (GPX) and superoxide dismutase (SOD) activities, indicating their role in BBTV inoculated and non-inoculated plants of Virupakshi (hill banana), a unique flavoured elite dessert banana cultivar and Grand Nain, which belongs to a Cavendish sub group occupying approximately 50% of area in the world.