Indole-3-acetic acid (IAA) is one of the most common plant hormones that regulate many aspects of growth and development of plants. Trichoderma harzianum, a plant growth promoting fungus, has the ability to produce IAA. However, various environmental factors influence the formation of the hormone. The objective of this study was to optimize the environmental condition for the production of IAA by Trichoderma harzianum InaCC F88 strain. The effects of L-tryptophan concentration, temperature, pH, salinity, and incubation time on IAA production and biomass were studied. The in vitro evaluations were carried out in the axenic condition of Luria-Bertani Medium. Supplementation of 1% L-tryptophan in the medium gives maximum IAA production. The most favourable initial pH and temperature for IAA production are 6.0 and 27°C, respectively. In the salinity test, the medium containing 1% NaCl yielded maximum IAA formation. After 4 days of incubation, the concentration of IAA reached equilibrium. Hence, optimum IAA production in liquid fermentation could be achieved by manipulating those factors.

Tricoderma harzianum have been widely used as a biocontrol agent for the suppression of soil-borne pathogens. The objective of this work was to evaluate the potential of T. harzianum strains to control Fusarium oxysporum f.sp. cubense (Foc), a well-known soil-borne pathogen that associated with banana wilt disease. In this study, ten isolates of T. harzianum strain isolated from various regions in Java were evaluated through two in vitro antagonistic approaches, dual culture test and volatile organic compound (VOC) producing test. All strains showed antagonistic activity against Foc according to the dual culture test with various degree of antagonism from efficient antagonism to highly efficient antagonism. Observations after five days, the antagonists overgrew 63% until 88% of medium surface. Similarly, all strains produced toxic volatile metabolites that having significant effects on the growth and development of the Foc. After seven days of exposure with antagonists, the mycelial growth of the test pathogen was inhibited by 24% until 44%. These results indicate that different strains showed variability in the level of antagonism.

Eukaryotic protein phosphatase 4 (PP4) is a PP2A-type protein phosphatase that is part of a conserved complex with regulatory factors PSY2 and PP4R2. Various lines of Arabidopsis thaliana with mutated PP4 subunit genes were constructed to study the so far completely unknown functions of PP4 in plants. Mutants with knocked out putative functional homolog of the PSY2 LIKE (PSY2L) gene were dwarf and bushy, while plants with knocked out PP4R2 LIKE (PP4R2L) looked very similar to WT. The psy2l seedlings had short roots with disorganized morphology and impaired meristem. Seedling growth was sensitive to the genotoxin cisplatin. Global transcript analysis (RNA-seq) of seedlings and rosette leaves revealed several groups of genes, shared between both types of tissues, strongly influenced by knocked out PSY2L. Receptor kinases, CRINKLY3 and WAG1, important for growth and development, were down-regulated 3–7 times. EUKARYOTIC ELONGATION FACTOR5A1 was down-regulated 4–6 fold. Analysis of hormone sensitive genes indicated that abscisic acid levels were high, while auxin, cytokinin and gibberellic acid levels were low in psy2l. Expression of specific transcription factors involved in regulation of anthocyanin synthesis were strongly elevated, e.g. the master regulator PAP1, and intriguingly TT8, which is otherwise mainly expressed in seeds. The psy2l mutants accumulated anthocyanins under conditions where WT did not, pointing to PSY2L as a possible upstream negative regulator of PAP1 and TT8. Expression of the sugar-phosphate transporter GPT2, important for cellular sugar and phosphate homeostasis, was enhanced 7–8 times. Several DNA damage response genes, including the cell cycle inhibitor gene WEE1, were up-regulated in psy2l. The activation of DNA repair signaling genes, in combination with phenotypic traits showing aberrant root meristem and sensitivity to the genotoxic cisplatin, substantiate the involvement of Arabidopsis PSY2L in maintenance of genome integrity.

Abstract. Sudiana A, Putri A, Napitupulu TP, Purnaningsih I, Idris, Kanti A. 2020. Growth inhibition of Fusarium solani and F. oxysporum by Streptomyces sasae TG01, and its ability to solubilize insoluble phosphate. Biodiversitas 21: 429-435. Actinomycetes have been widely explored for new antibiotic production, but not many studies explore its abilities to inhibit the growth of phytopathogenic fungi and solubilize insoluble phosphate hence stimulate the growth of plants. We isolated Actinomycetes from the soil. Based on morphology, physiology, and 16S rDNA analyses, the isolate is closely related to Streptomyces sasae. The strain was able to inhibit the growth of phytopathogenic fungi Fusarium solani, and Fusarium oxysporum. S. sasae produced secondary metabolites 2-methyl-1,3-dioxolane as the major constituent. The strain assimilated variable carbon sources include L-arabinose, D-fructose, D-glucose, D-mannitol, Lactose, raffinose, L-rhamnose, and sucrose. The strain grew at pH 6.0 to 8.0, and at salinity (1-3%). Their growth was affected by the salinity level. The strain solubilized Ca-P at 1-3% salinity, but their ability to solubilize phosphate was influenced by salinity. The strain was also able to solubilize rock phosphate. Their ability to solubilize less soluble phosphate and inhibit the growth of F. solani and F. oxysporum may imply that this strain is potential for biocontrol agents. The 16S rRNA gene was submitted to DDBJ with the entry number 5df623c1a3c8820021322a36.TG01, and the accession number is LC514451.

The utilization of natural materials is likely to increase nowadays, including for aromatherapy purposes. In this research, aromatherapy candle had been made from the volatile oil of Cymbopogon nardus (L.) Rendle (citronella grass). The aims of this research is to observe the influence of aromatherapy candle containing citronella grass oil toward the blood pressure of hypertension patients at Community Health Center Kapuk II Jakarta, Indonesia. This research used pre-experiment design with one group pretest-posttest design. The population was elderly who had high blood pressure. A sample of 43 peoples were obtained by simple random sampling technique. Data analysis was done by t-dependent test (paired t-Test) with significance value α = 0,05. The result of paired t-Test from pretest and posttest of systole blood pressure was obtained with P value 0,000 and paired t-test from pretest and posttest of diastolic blood pressure was obtained with P value 0,012. It can be concluded that there was an influence of aromatherapy candles of Cymbopogon nardus (L) Rendle toward lowering blood pressure in hypertension patient at Puskesmas Kapuk II Jakarta Indonesia.

Compared to other cereal crops, sorghum has a higher drought tolerance trait. However, efforts are needed to increase the productivity of sorghum, particularly in drought marginal land. One strategy to be implemented is the utilization of soil microorganisms formulated with biocarrier. Therefore, the aim of this study was to evaluate the influence of the fungal strain Aspergillus niger and Trichoderma harzianum formulated with compost and zeolite as biocarrier towards vegetative growth of sorghum. The field experiment was designed as a randomized block designed, factorial pattern with 4 replications. The first factor was selecting biocarrier, namely zeolite, compost, and a mixture of zeolite: compost (1:1). The second factor was the fungal inoculants, A. niger, and T. harzianum. The observed parameter was the growth profile of sorghum during vegetative growth, including stalk diameter and height. The results showed that the type of biocarrier, as well as the fungal strains did influence the growth of sorghum. The highest stalk diameter and height of sorghum were obtained after application of A. niger formulated with a mixture of zeolite: compost (1:1), with 17% and 41.2% higher than control, respectively. This condition shows that a mixture of zeolite and compost is seemingly able to create better micro-ecological conditions for fungal microbes to function effectively. Therefore, our findings suggested the addition of zeolite to compost for the application of biocarrier in the field experiment.

Oil spill accidents occur several times in the Indonesian sea, including Jakarta Bay. Studies on the application of oil spill bio-degradation techniques need to be developed but require baseline data on microbe species diversity and functions. We isolated several bacteria from Pulau Pari that can degrade hydrocarbons (hexadecane, phenantrene, and dibenzothiophene) by using two step enrichment culture technique. The isolated microbes belong to several taxa, including α-subclass Proteobacteria, β-subclass Proteobacteria, γ-subclass Proteobacteria, the gram-positive high GC content (Actinobacteria), and Bacillus group. These marine bacteria degrade not only alkanes but also polyaromatic hydrocarbons (phenanthrene and dibenzothiophene). Alpha and gamma Proteobacteria were predominant alkane and polyaromatic hydrocarbons-degrading bacteria. The ability of those bacteria to degrade both alkanes and polyaromatic hydrocarbon is a key-important trait for enhancing bioremediation of oil spills.

Banana rhizosphere harbors a unique diversity of microbes including fungi that play critical roles in the growth of the plant host as well as might be important for biologically controlling the fungal soil-borne pathogens particularly Fusarium oxysporum f.sp. cubense (Foc), the causing agent of devastating Panama wilt. Among other fungi, we have succeeded to isolate a Trichoderma species from rhizosphere of healthy banana. Molecular identification revealed the isolate as Trichoderma virens InaCC F1030 (being collection of Indonesian Culture Collection or InaCC). Therefore, the aim of this study was to investigate the biological control of our isolate against Foc as well as plant growth promoting ability through its ability to produce auxin (indole-3-acetic acid/IAA). Two approaches were employed to evaluate the antagonism of our isolate against Foc, through direct confrontation test and volatile organic compounds (VOCs) producing. We found that our isolate was considered as antagonistic to the Foc, but not highly antagonistic according to direct confrontation assay. It was also revealed that our isolate produces the VOCs that inhibited around 50% of the mycelial growth of the test pathogen after six to seven days of exposure. Our isolate was able to produce the IAA in axenic submerged fermentation condition particularly in the presence of the precursor L-tryptophan. IAA production ability as well as the mycelial biomass of fungus were increased approximately 17% and 120% respectively as the effect of supplementation of 0.1% of L-tryptophan. These in vitro bioassays lead us to conclude that somehow our isolate T. virens InaCC F1030 has potency to be utilized as biocontrol and biofertilizer agent.