Toan Le Thanh^1,2*, Nguyen Huy Hoang², Kanjana Thumanu³, Channon Saengchan², Jayasimha Rayalu Daddam⁴, Rungthip Sangpueak², Narendra Kumar Papathoti², Kumrai Buensanteai²

¹Crop Protection Department, College of Agriculture, Can Tho University, Can Tho city, 94000, Vietnam

²School of Crop Production Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand

³Synchrotron Light Research Institute, Nakhon Ratchasima, 30000, Thailand

⁴Department of Animal Science, Agriculture Research Organization, Volcani Center, Rishon Lezion 7505101, Israel

Abstract

Bacterial leaf blight (BLB) of rice has a high epidemic potential and usually causes severe damage. This research was conducted to assess the efficacy and characterize the mechanism of the systemic resistance of rice plants induced by the Bacillus subtilis strain CaSUT007 to BLB. The results revealed 30% reduction in the severity of BLB in the treated rice plants, and real-time PCR measurements indicated a significant 1.1–1.2-fold increase in their concentrations of the defense genes of phenylalanine ammonia-lyase (PAL) and ascorbate peroxidase (APX). In addition, Fourier transformed infrared spectroscopy characterization of the biochemical changes in the rice leaves indicated alterations to the lignins, pectins, and amide I vibrations – these lead to the generation of defense barriers and the reinforcement of cell walls against Xanthomonas infection and invasion, thereby contributing to disease reduction. Phylogenetic trees of pal and apx revealed a significant number of polytomies among these two gene families. Moreover, analysis of the active sites of the protein PAL and APX showed one serine rotamer and a single mutation-sensitive glutamic acid residue in the region of the binding site/pocket. The possible interactions of PAL and APX with other proteins revealed insight into the defense mechanism: APX6 interacts directly with MDAR5, MDRA3, DHAR1, and other important defense proteins, while PAL has direct interactions with 4CL4, 4CLL9, and 4CL3, among other defense proteins. Therefore, treatment with the B. subtilis strain CaSUT007 promoted faster, stronger and more intense responses in rice plants against BLB.

Keywords: Bacillus subtilis, Defense genes, Leaf blight, Protein interaction

Amanda Putri Irawan¹, Amalia Rahmawati¹, Ulfa Abdila Fahmi¹, Arief Budiman², Khusnul Qonita Maghfiroh¹, Tia Erfianti¹, Dea Putri Andeska¹, Renata Adaranyssa Egistha Putri¹, Istini Nurafifah¹, Brilian Ryan Sadewo², Eko Agus Suyono^1*

¹Faculty of Biology, Universitas Gadjah Mada, Yogyakarta, Indonesia. Jl. Teknika Sel., Sendowo, Sinduadi, Kec. Mlati, Kabupaten Sleman, Daerah Istimewa Yogyakarta 55281, Indonesia

²Department of Chemical Engineering, Faculty of Engineering, Universitas Gadjah Mada, Indonesia. Sendowo, Sinduadi, Kec. Mlati, Kabupaten Sleman, Daerah Istimewa Yogyakarta 55284, Indonesia

Abstract

Microalgae harvesting is critical to remove water from algal growth media with solid-liquid separation. Bioflocculation has the same principle as flocculation. Using solid-liquid separation, microalgae harvesting removes moisture from the algal growth substrate. The same idea underlies flocculation and bioflocculation. Using fungal and bacterial bioflocculants requires a special medium that is different from the microalgae medium, that fungi and bacteria can contaminate microalgae, so it is not recommended to be used as a bioflocculant agent. Microalgae Anabaena sp. was chosen in this study as a bioflocculant agent since it can produce exopolysaccharides (EPSs). Dissolved proteins and carbohydrates make up EPSs. This investigation looked into employing Anabaena species to extract Chlorella species. The harvest day was used to measure the parameters. A spectrophotometer was used to measure the precipitation percentages. Bligh and Dyer’s methods were used to measure lipid contents. The phenol-sulfate was used to perform carbohydrates. Bradford method was used to quantify proteins. The ratio of 1:1.25 was determined to have the best proportion of flocculation and carbohydrate content (Chlorella sp. : Anabaena sp.). The ratio of 1:1 was determined to have the maximum cell lipid and protein content (Chlorella sp.: Anabaena sp.). The application of this study will be beneficial to design effective methods for harvesting microalgae using biological materials such as other microalgae.

Keywords: Bioflocculation, Anabaena sp., Chlorella sp., Exopolysaccharides

Leilidyn Y. Zurbano^1*, Chester C. Deocaris², Carmelita P. Mapanao³, Arnel O. Rendon³, Lourdes V. Alvarez³

¹Agriculture Department, Polytechnic University of the Philippines, Lopez, Quezon Branch, Quezon Province, Philippines

²Department of Physical Science, College of Science, Polytechnic University of the Philippines, Sta. Mesa, Manila, Philippines

³Department of Biology, College of Science, Polytechnic University of the Philippines, Sta. Mesa, Manila, Philippines

Abstract

Plant-parasitic nematodes are serious pests causing important crop losses worldwide. Hence, this study was conducted to determine the occurrence of plant-parasitic nematodes (PPNs) in healthy and unhealthy pineapple crops. To determine if the infestation is prevalent, a soil metabarcoding analysis was done. Six soil samples were obtained from the rhizospheres of Red Spanish pineapple farm in Mabitac, Laguna, Philippines. They were freeze-dried and brought to the laboratory for metagenomics analysis using Primers NemF and 18Sr2b. The results showed uncultured Eukaryotes (43.1%) nematodes (31.2%), Platyhelminthes (6.9%), Apicomplexa (6.5%), Annelida (5.0%), Rotifera (3.6%), Arthropoda (1.8%), Ascomycota (1%), unidentified (0.4%) and Basillariophyta, Cercozoa, Chytridiomycota, Mollusca and Mucoromycota with 0.1%. In total, 374,410 sequence reads were obtained and were clustered into 117 OTUs at 97% similarity. In assessing the nematode community structure, it yielded 26,565 nematodes; 5,315 nematodes were obtained from the rhizosphere of healthy samples, and 21,250 were from the unhealthy ones. The fungivore Apelenchus avenae (Bastian 1865) was the most prevalent (47.8% and 43.9%) in both locations. Other nematodes found on the plant rhizospheres were Rhabdolaimus aquaticus (de Man), Acrobeloides varius, Rotylenchulus reniformis (Linford and Oliveira, 1940), Aphelenchoidinae sp., Panagrolaimoidea sp., and two unidentified nematodes. The Basiria sp., Alaimus sp., and two other unidentified nematodes were the only ones found in the rhizosphere of unhealthy pineapple plants. Meanwhile, Mesocriconema onoense, Aphelenchoides sp., Ditylenchus gilanicus, and an unidentified nematode were found in the rhizosphere of healthy pineapple plants. Phylogenetic analyses of the nematode communities show that only Orders Rhabditida and Enoplida are associated with the crop and the Family Aphelenchoididae is distant from Rhabditida, thus, dividing the clade into three. The first clade consists of diverse nematode communities of fungivores, bacterivores, predators, and plant and insect parasites. The second clade consists of bacterivore nematodes found in moist environments, and the third clade comprises mainly Aphelenchoididae species, mostly plant parasites.

Keywords: Metabarcoding, Acrobeloides varius, Aphelenchus avenae, Ditylenchus gilanicus, Mesocriconema onoense, Rhabdolaimus aquaticus, Rotylenchulus reniformis

Otie Victoria^1,2, Udo Idorenyin³, Matsuura Asana⁴, Liu Jia², Liang Shuoshuo², Shao Yang⁵, Itam Michael Okoi⁶, An Ping^2*, Eneji Anthony Egrinya¹

1Department of Soil Science, Faculty of Agriculture, Forestry and Wildlife Resources Management, University of Calabar, P.M.B. 1115, Calabar, Nigeria

2Arid Land Research Centre, Tottori University, Hamasaka 680-0001, Tottori, Japan

3Department of Crop Science, Faculty of Agriculture, Forestry and Wildlife Resources Management, University of Calabar, P.M.B. 1115, Calabar, Nigeria

4Faculty of Agriculture, Shinshu University, 8304, Kamiina County, Nagano 399-4598, Japan

5College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China

6Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing 48824, MI, USA

Abstract

Salt stress is a key ecological challenge to wheat establishment at the early stage of germination, especially in drylands. A germination experiment was conducted to determine whether an exogenous seed treatment with 24-epibrassinolide could mitigate salinity stress effects on wheat germination. Seeds of the Sudanese wheat cv. Imam were treated with 24-epibrassinolide (BR1) or without (BR0) at eleven concentrations of sodium chloride (NaCl) (0.00, 1.56, 3.13, 4.69, 6.25, 7.81, 9.38, 10.94, 12.50, 14.06 and 15.63 dSm-1), in a 2 x 11 factorial experiment arranged into a completely randomized design. Seed germination was progressively delayed with increasing salinity and the daily germination was reduced significantly. The germination average time and relative injury rate increased considerably (p≤0.05) at salt levels of 7.81 dSm-1or more. The inhibitory effects of salinity on germination were significantly (p≤0.05) reversed by seed treatment with BR1. Wheat cv. Imam tolerated salt stress up to 6.25 dSm-1 at BR0 with respect to velocity of germination, germination rate, final germination rate, germination percentage and germination index, relative to no salt (0.00 dSm-1). An early uniform establishment of wheat in saline media could be enhanced by seed treatment with BR.

Keywords: Arid region, Plant growth hormone, Triticum aestivum (L), Abiotic stress

Lily Ishaq*, Agnes V Simamora, Peters O. Bako, Yoke I Benggu, Moresi M. Airthur, Effy Roefaida, Ellias St O Nguru

Department of Agrotechnology, Faculty of Agriculture, Nusa Cendana University. Jl. Adi Sucipto Penfui Kupang, East Nusa Tenggara, Indonesia

Abstract

Citrus is an important commercial crop in Timor Tengah Selatan, East Nusa Tenggara, Indonesia, but many trees are suffering a decline in health. As citrus is heavily dependent on arbuscular mycorrhizal fungi (AMF), this study investigated the abundance of AMF in the rhizosphere of healthy and declining trees in citrus orchards at 12 geographical locations. In each orchard, 6 soil and 6 root samples representing 3 healthy and 3 declining trees were collected. The soil was analyzed for AMF spore abundance as well as physical (texture) and chemical properties (organic carbon, nitrogen, phosphorus, potassium, pH, and soil exchangeable capacity), while the fine roots of citrus were assessed for colonization. The data were analyzed using analysis of variance (ANOVA) where the health condition of the trees was under the geographical location/site factor. The results showed that the abundance of AMF spores was significantly affected by the geographical location from where the soils were collected, but the health condition of the trees had no effect. However, AMF colonization was significantly affected by both site and tree health. The number of AMF morphotypes tended to be higher under healthy trees than under declining trees. Soil analysis indicated that soil fertility (N and organic C) may be important for tree health. These results provided a new perspective on the possible involvement of AMF and soil nutrients in citrus decline. Further studies are required to define the interactions between AMF, soil fertility, and disease incidence to identify strategies for managing citrus decline in the region.

Keywords: Arbuscular mycorrhizal fungi, Citrus decline, Orchard management, Orchard location, Southeast Asia