Combined Use of Two Trichoderma Strains to Promote Growth of Pakchoi (Brassica chinensis L.)

Trichoderma spp., which widely exist in nature, are always used as plant growth-promoting stimulants. However, there is little reporting about the combined use of Trichoderma strains to promote growth of plants. We explored two different Trichoderma strains (Trichoderma atroviride LX-7 and Trichoderma citrinoviride HT-1) and a mixture of the two on the growth-promoting effects of pakchoi. In this study, in vitro-promoting traits of two Trichoderma strains were determined, and six treatments were used: T. atroviride LX-7, T. citrinoviride HT-1, different mixtures of these two (1:1, 1:2 and 2:1) and no inoculation in the seed germination and pot experiment. The results showed that T.atroviride LX-7 and T. citrinoviride HT-1 had the ability of siderophore and indol acetic acid (IAA) production, and LX-7 had the capacity for potassium solubilization. The highest seed germination percentage (GP), germination energy (GE), germination index (GI), vitality index (VI) and growth of radicles and plumules was observed in the LX-7 + HT-1 (1:1) combination, the highest biomass and quality of plants was observed in the LX-7 + HT-1 (1:2) inoculation (followed by a single LX-7 or HT-1 strain inoculation), while the lowest values were obtained in the untreated seeds or plants. On the basis of this study, combined use of two Trichoderma strains had greater benefits for growth and quality of pakchoi, making this formulation attractive for future field applications.

In Vitro Responses of Alfalfa Root (Medicago Sativa L.) to Salt stress and Melatonin

Alfalfa (Medicago sativa L.) is the most cultivated forage legume. The growth and development of alfalfa roots are limited by salt stress. Growth regulator is an essential role of melatonin in plants, especially in root involved in stress tolerance. In this study, alfalfa roots under in vitro salt stress (150 and 200 mM NaCl) were pretreated with different concentrations of melatonin (0.1, 10 and 15 μM). principal component analysis to find out the best targets for melatonin and salinity. Exogenous utilization of melatonin in alfalfa roots significantly elevated the compatible solutes particularly glycin betaein (GB), soluble carbohydrate and K+ content. Principal component analysis revealed that, Indol acetic acid (IAA) content, GB, flavonoids, carbohydrate and Na+ were the best melatonin targets. Furthermore, salinity affected ROS, H2O2, O2-, malondialdehyde (MDA), phenylalanine ammonia-lyase (PAL), K+/Na+ ratio and tyrosine ammonia-lyase (TAL) enzymes were augmented, and electrolyte leakage, Na+ accumulation decreased in the saline medium.

Enterobacteria isolated from an agricultural soil of Argentina promote plant growth and biocontrol activity of plant pathogens

Bacteria promote growth by different mechanisms like phosphate (Pi) solubilization, Indol Acetic Acid (IAA) synthesis and siderophores production. The purpose of this study was to isolate bacteria that promote the growth of plants and may also act as antagonistic organisms of plant pathogens. Pi solubilizing microorganisms that were isolated from the soils of Tres Arroyos, Buenos Aires; were also able to synthesize IAA and produce siderophores. The ability of these bacteria to solubilize Pi was directly related with the synthesis of organic acids that lowered the pH and was not related with phosphatase activity. The ability of the organisms to solubilize Pi was indirectly related with the amount of soluble Pi present in the media. Though Pi solubilizing microorganisms are mainly associated with the rhizoplane exudates, in this case did not induce Pi solubilization. In addition to promote plant growth, these bacteria proved to be antagonistic of plant pathogens such as Fusarium graminearum and F. solani.

KARAKTERISASI DAN IDENTIFIKASI BAKTERI RIZOSFER TANAMAN SAWIT JAMBI

AbstrakBakteri rizosfer adalah bakteri yang terdapat pada daerah perakaran tanaman yang diketahui memiliki keanekaragaman tinggi. Bakteri rizosfer memiliki berbagai peran seperti menyediakan nutrisi bagi tanaman, melindungi tanaman dari infeksi bakteri patogen, menghasilkan hormon pertumbuhan seperti indol acetic acid, pelarut fosfat, pengikat nitrogen, dan lain-lain. Dengan berbagai kemampuan dan peran tersebut, maka perlu eksplorasi bakteri rizosfer tanaman sawit khususnya di daerah perkebunan agar diketahui kelompok bakteri rizosfer, sehingga dapat dimanfaatkan secara optimal. Penelitian ini bertujuan untuk mengetahui kelompok dan keragaman bakteri rizosfer pada tanaman sawit yang berumur 8, 11, dan 14 tahun. Penelitian dilakukan dengan pendekatan konvensional dengan karakterisasi morfologi dan uji biokimia. Dari umur-umur tersebut, didapatkan 18 isolat yang terdiri dari 11 genus, yaitu Bacillus, Azospirillum, Actinobacillus, Xanthobacter, Enterococcus, Paenibacillus, Klebsiella, Pseudomonas, Arthrobacter, Micrococcus, dan Streptococcus. Bakteri rizosfer tanaman sawit memiliki keragaman genus yang sama pada umur 8, 11, dan 14 tahun. Genus bakteri yang didapatkan dapat dimanfaatkan sebagai PGPR (Plant Promoting Rhizobacteria).Abstract Rhizosphere bacteria are bacteria found in root areas. Rhizosphere bacteria have various roles such as providing nutrients for plants, protecting plants from infection pathogenic bacteria, producing growth hormones such as indol acetic acid, phosphate solvents, nitrogen binders, and others. By having these various abilities and roles, it is necessary to explore the bacteria of oil palm plants, especially in the plantation areas so that the group of rhizosphere bacteria can be identified and then utilized optimally. This study aims to determine the group and diversity of rhizosphere bacteria in oil palm plants that are 8, 11, and 14 years old. The research was conducted conventionally by observing morphological and biochemical characterization. At those ages, 18 isolates were consisting of 11 genera, namely Bacillus, Azospirillum, Actinobacillus, Xanthobacter, Enterococcus, Paenibacillus, Klebsiella, Pseudomonas, Arthrobacter, Micrococcus, and Streptococcus through conventional methods. Rhizosphere bacteria in oil palm plants have the same genus diversity at the ages of 8, 11, and 14 years. The bacterial genus obtained can be used as PGPR (Plant Promoting Rhizobacteria).

Isolation and characterization of rhizospheric Streptomyces spp. for the biocontrol of Fusarium wilt (bayoud) disease of date palm (Phoenix dactylifera L.)

Fusarium wilt of date palm (Phoenix dactylifera L.) caused by Fusarium oxysporum f.sp. Albedinis is one of the most destructive diseases in North Africa spicily in Algeria and Morocco. The objectives of this work were the isolation, identification and biocontrol efficacies testing of rhizospheric actinobacteria of medicinal plant Astragalus gombo against fusarium wilt disease in date palm. Five rhizospheric Streptomyces spp. Isolates bi02, bi21, bi24, bi26 and bi28 showed the largest zone of inhibition demonstrating a potent effect against F. oxysporum f.sp. Albedinis and a broad spectrum of antimicrobial activities against the test microorganisms. All these selected isolates produced indol acetic acid (IAA) at different levels, exhibited higher activity of phosphate solubilisation and siderophore production as well as chitinase and protease activities. The inoculation of infected date palm with the five Streptomyces spp. Increased all parameters of growth measured in controlled conditions. The study revealed that the five Streptomyces spp. could be a potential biocontrol agent for controlling palm and also promoting growth of plants.

KAJIAN INDUKSI KALUS RUMPUT LAUT Kappaphycus alvarezii UNTUK PRODUKSI EMBRIO SOMATIK

Untuk mendukung program transgenesis pada rumput laut, embrio somatik dapat digunakan sebagai material untuk transfer gen baik secara individu sel ataupun kluster sel embriogenik, sehingga mempercepat keberhasilan dengan peluang transformasi yang lebih tinggi. Penelitian ini bertujuan untuk mengkaji induksi kalus rumput laut K. alvarezii untuk produksi sel embrio somatik (e.s.) dengan beberapa rasio zat pengatur tumbuh (ZPT) dan konsentrasi agar media induksi, sampai sel menjadi filamen. Penelitian terdiri atas dua tahap: Tahap (1) induksi kalus, dengan rasio ZPT asam indol asetat (IAA):kinetin = 0,5:0,0 mg/L; 1,0:1,0 mg/L; dan 2,0:0,2 mg/L dengan konsentrasi agar media induksi = 0,6%; 0,8%; 1,0%; dan 1,5%. Tahap (2) regenerasi massa sel e.s., dengan rasio IAA:kinetin = 0,1:1,0 mg/L; 0,0:0,1 mg/L dan tanpa ZPT dengan konsentrasi agar media = 0,4%; 0,6%; dan 0,8%. Untuk perkembangan sel-sel e.s. lebih lanjut dipelihara pada kultur cair. Hasil penelitian menunjukkan pada tahap induksi kalus, rasio IAA: kinetin = 1:1 mg/L dengan konsentrasi agar media 0,8% dan 1,0% menghasilkan persentase induksi kalus tertinggi (90%). Pada tahap regenerasi massa sel e.s., ZPT tidak berpengaruh terhadap perkembangan massa sel e.s., di mana tanpa ZPT dengan konsentrasi agar 0,6% memperlihatkan perkembangan tertinggi (rata-rata diameter massa sel 5 mm). Pada media cair, perkembangan sel e.s. dari single cell ukuran 3-4 mm menjadi filamen-filamen ukuran rata-rata 0,5 mm dapat dicapai dalam satu bulan kultur. Keberhasilan produksi sel e.s. K. alvarezii, selain sebagai material untuk transfer gen juga dapat dijadikan acuan dalam produksi benih rumput laut kultur jaringan.To support the program of seaweed transgenesis, somatic embryo can be used as a materials for gene transfer purpose either by individual or cluster of cells in accelerating the higher rate of transformation. This research aims to study the callus induction of seaweed K. alvarezii for production of somatic embrio (s.e) cell by different ratio of growth regulators (GR) and agar media concentrations. The study consists of two stages: stage (1) callus induction to the cells filament using GR of indol acetic acid (IAA):kinetin in ratio of 0.5:0.0 mg/L; 1.0:1.0 mg/L; and 2.0:0.2 mg/L on the media agar concentration of 0.6%; 0.8%; 1.0%; and 1.5%, and stage (2) regeneration of the cell mass of s.e, using GR of IAA:kinetin in ratio of 0.1:1.0 mg/L; 0.0:0.1 mg/L on the media agar concentration of 0.4%; 0.6%; and 0.8%. For further maintenance, the s.e cells were cultured in liquid media. The results of callus induction showed that the ratio of IAA:kinetin (1:1) on the media agar concentration of 0.8% and 1.0% produced the highest callus induction (90%). The study of mass cell regeneration of s.e showed did not different of GR IAA:kinetin ratio of the cell mass development, but the media agar concentration of 0.6% and 0.4% showed the higher growth of cell mass (in diameter size of 4-5 mm). The development of cells culture of s.e from the size of 3-4 mm to filament of 0.5 mm could be reached in one month of culture period. The success of K. alvarezii s.e production will be helpful not only as a material for gene transfer but also as a reference on tissue culture for seed production of seaweed.