The Small GTPase FgRab1 Plays Indispensable Roles in the Vegetative Growth, Vesicle Fusion, Autophagy and Pathogenicity of Fusarium graminearum

Rab GTPases are key regulators of membrane and intracellular vesicle transports. However, the biological functions of FgRab1 are still unclear in the devastating wheat pathogen Fusarium graminearum. In this study, we generated constitutively active (CA) and dominant-negative (DN) forms of FgRAB1 from the wild-type PH-1 background for functional analyses. Phenotypic analyses of these mutants showed that FgRab1 is important for vegetative growth, cell wall integrity and hyphal branching. Compared to the PH-1 strain, the number of spores produced by the Fgrab1DN strain was significantly reduced, with obviously abnormal conidial morphology. The number of septa in the conidia of the Fgrab1DN mutant was fewer than that observed in the PH-1 conidia. Fgrab1DN was dramatically reduced in its ability to cause Fusarium head blight symptoms on wheat heads. GFP-FgRab1 was observed to partly localize to the Golgi apparatus, endoplasmic reticulum and Spitzenkörper. Furthermore, we found that FgRab1 inactivation blocks not only the transport of the v-SNARE protein FgSnc1 from the Golgi to the plasma membrane but also the fusion of endocytic vesicles with their target membranes and general autophagy. In summary, our results indicate that FgRab1 plays vital roles in vegetative growth, conidiogenesis, pathogenicity, autophagy, vesicle fusion and trafficking in F. graminearum.

A Putative D-Arabinono-1,4-lactone Oxidase, MoAlo1, Is Required for Fungal Growth, Conidiogenesis, and Pathogenicity in Magnaporthe oryzae

Magnaporthe oryzae is the causal agent of rice blast outbreaks. L-ascorbic acid (ASC) is a famous antioxidant found in nature. However, while ASC is rare or absent in fungi, a five-carbon analog, D-erythroascorbic acid (EASC), seems to appear to be a substitute for ASC. Although the antioxidant function of ASC has been widely described, the specific properties and physiological functions of EASC remain poorly understood. In this study, we identified a D-arabinono-1,4-lactone oxidase (ALO) domain-containing protein, MoAlo1, and found that MoAlo1 was localized to mitochondria. Disruption of MoALO1 (ΔMoalo1) exhibited defects in vegetative growth as well as conidiogenesis. The ΔMoalo1 mutant was found to be more sensitive to exogenous H2O2. Additionally, the pathogenicity of conidia in the ΔMoalo1 null mutant was reduced deeply in rice, and defective penetration of appressorium-like structures (ALS) formed by the hyphal tips was also observed in the ΔMoalo1 null mutant. When exogenous EASC was added to the conidial suspension, the defective pathogenicity of the ΔMoalo1 mutant was restored. Collectively, MoAlo1 is essential for growth, conidiogenesis, and pathogenicity in M. oryzae.

Molecular characterization and vegetative growth of pathogenic seed-borne fungus, Curvularia lunata of tomato and its in vitro control measures

Present studies were conducted to isolate and identify the seed-borne pathogenic fungus from the selected tomato variety through morphological and molecular techniques based on the sequencing of internal transcribed spacer (ITS) region of 18S rDNA. According to the colony and conidial features, the fungus was identified as Curvularia sp. The obtained ITS sequencing showed above 99% similarity with Curvularia lunata in the NCBI database. The sequence of the fungus was deposited in NCBI GenBank under the accession number: ITS, MH382879.1. Besides, the phylogenetic tree further confirmed the taxonomic position of the studied fungus. Growth characteristics of the fungus on nine different fungal culture media were evaluated, in which Honey peptone agar, Carrot agar, Potato sucrose agar, and Kauffman’s agar were found the most suitable. The maximum vegetative growth of the fungus was recorded at 30°C temperature and pH conditions. The bio-control potential of five different antagonists against the studied fungus was assessed, in which Trichoderma harzianum showed the better performance to restrict mycelial growth. Three ethanolic plant extracts were also evaluated, in which Lowsonia inermis L. exhibited above 60% mycelial growth inhibition of the fungus. Among three tested fungicides, Tilt 250 EC was found as an excellent fungicide to inhibit mycelial growth of C. lunata under in vitro conditions. Int. J. Agril. Res. Innov. Tech. 11(2): 124-132, Dec 2021

Seed treatment using rhizobacteria as plant growth promotion of two chili variety (Capsicum annuum L.)

The research aims to find out the effect of pre-germination treatment seeds using rhizobacteria as plant growth promotion of two varieties of red chili peppers in the field. The experiment used a randomized design of factorial groups. Factors studied were varieties (V) and rhizobacteria types (R). The variety factor consists of 2 varieties namely PM999 (V1) and Kiyo F1 (V2). While the type of rhizobacteria factor tried consists of 8 treatment, namely, control (R0), Azotobacter sp. (R1), B. megaterium (R2), P. atmuta (R3), B. alvei (R4), Flavobacterium sp. (R5), B. coagulans (R6), B. firmus (R7) and B. pilymixa (Rs). Each treatment was repeated 3 times, so there were 48 experimental units. Each unit of experiment is represented by 5 sample plants. The data was analyzed using ANOVA and continued with DMRT test at real level α = 0.05. The results showed that vegetative growth and production of chili plants until the age of 45 days after planting in each variety is not dependent on the pre-germination treatment of seeds with rhizobacteria. But the varieties of chili plants used affect vegetative growth and production. PM999 varieties are superior to the Kiyo F1 variety. Pre-germination treatment of seeds using rhizobacteria is relatively effective in improving vegetative growth and yield of chili plants. Among the 8 isolates rizobacteria isolate Azotobacter sp., B. megaterium, B. coagulants, Flavobacterium sp., and P. atmuta relatively effective to provide an increased effect on the growth and production of chili plants.

Effect of Organic Fertilizer Form and Dosage on Soil Chemical Properties, Leaf Macro Nutrient Content and Vegetative Growth of Siamese Orange (Citrus nobilis Lour) seedlings

Orange is a national superior commodity that has an important role in increasing foreign exchange for the country. However, the development of citrus cultivation in Indonesia is still relatively low, probably due to soil fertility degradation. Therefore, this study aimed to analyze the effect of differences in the application of organic fertilizer (form and dose) and their interaction on soil chemical properties, nutrient concentration in the leaf (i.e. N, P, K), and growth in Siamese citrus seedlings. The treatments included the application of a combination of forms and doses of organic fertilizer, namely SD1 (powder dose 2 t ha-1), SD2 (powder dose 4 t ha-1), SD3 (powder dose 6 t ha-1), SD4 (powder dose 8 t ha-1), SD5 (powder dose 10 t/ha), GD1 (granule dose 2 t ha-1), GD2 (granule dose 4 t ha-1), GD3 (granule dose 6 t/ha), GD4 (granule dose 8 t ha-1) and GD5 (granule dose 10 t ha-1). The results showed that there was a significant difference in the interaction between form and dose of organic fertilizer only in the number of primary branches at 4 WAP (weeks after application) with the highest values was found in powder organic fertilizer at a dose of 8 t ha-1 and granules organic fertilizer at a dose 10 t ha-1. In addition, the application of powder organic fertilizer application had a higher plant height at 10-12 WAP as compared to the application of granule organic fertilizer.

Reduced Irrigation during Orchard Establishment Conserves Water and Maintains Yield for Three Cider Apple Cultivars

Irrigation water productivity is a priority for sustainable orchard management as water resources become more limiting. This study evaluated reduced irrigation (RI) as a management strategy for cider apple (Malus domestica Borkh.) production in 2019 and 2020 in northwestern Washington, which has a Mediterranean climate and averages 14.1 cm of precipitation from June to September. RI was evaluated on three cider apple cultivars, Dabinett, Porter’s Perfection, and Golden Russet, in their third and fourth leaf. Stem water potential (stem ψ) was measured weekly throughout the growing season to monitor water stress and implement the RI treatment: irrigation would be applied when stem ψ values dropped below −1.5 MPa, a threshold indicative of moderate water stress in apples. Soil water potential was monitored throughout the season, vegetative growth was assessed by measuring shoot length and non-destructive imaging of the plant canopy using lateral photography, and yield, fruit quality, and juice quality were measured at harvest. Moderate water stress as indicated by stem ψ did not occur either year, thus irrigation was never applied to the RI treatment plots. There was a negative relationship between average stem ψ and both yield and air temperature (P < 0.0001 for each); as yield increased by 5.9 kg per tree or temperature increased by 3.3 °C, stem ψ decreased by 0.1 MPa. The juice quality attributes of the three cultivars in this study were similar to their historic measures at this site and there were no differences due to irrigation treatment, likely because trees did not reach the threshold to induce physiological stress. Both years, trees in the RI treatment did not differ from the control treatment in vegetative growth, fruit yield, juice yield, or any juice quality attribute, but weight per fruit decreased by 7 g, and fruit firmness (measured only in 2020) increased by 2 N. Results from this study indicate that fruit yield and quality in an establishing orchard can be maintained when irrigation is reduced relative to crop water requirements that are estimated from a calculated water balance or relative to conventional grower practices for this region. This finding highlights the benefits of using plant water status to schedule irrigation.

Optimization of Photosynthetic Photon Flux Density and Light Quality for Increasing Radiation-Use Efficiency in Dwarf Tomato under LED Light at the Vegetative Growth Stage

Dwarf tomatoes are advantageous when cultivated in a plant factory with artificial light because they can grow well in a small volume. However, few studies have been reported on cultivation in a controlled environment for improving productivity. We performed two experiments to investigate the effects of photosynthetic photon flux density (PPFD; 300, 500, and 700 μmol m−2 s−1) with white light and light quality (white, R3B1 (red:blue = 3:1), and R9B1) with a PPFD of 300 μmol m−2 s−1 on plant growth and radiation-use efficiency (RUE) of a dwarf tomato cultivar (‘Micro-Tom’) at the vegetative growth stage. The results clearly demonstrated that higher PPFD leads to higher dry mass and lower specific leaf area, but it does not affect the stem length. Furthermore, high PPFD increased the photosynthetic rate (Pn) of individual leaves but decreased RUE. A higher blue light proportion inhibited dry mass production with the same intercepted light because the leaves under high blue light proportion had low Pn and photosynthetic light-use efficiency. In conclusion, 300 μmol m−2 s−1 PPFD and R9B1 are the recommended proper PPFD and light quality, respectively, for ‘Micro-Tom’ cultivation at the vegetative growth stage to increase the RUE.