Section 3 Biological Aspects

**65**

**Chapter 5**

**Abstract**

of PGPF in sustainable agriculture.

root colonization, formulation

**1. Introduction**

Application and Mechanisms of

Plant Growth Promoting Fungi

Plant growth-promoting fungi (PGPF) constitute diverse genera of nonpathogenic fungi that provide a variety of benefits to their host plants. PGPF show an effective role in sustainable agriculture. Meeting increasing demand for crop production without damage to the environment is the biggest challenge nowadays. The use of PGPF has been recognized as an environmentally friendly way of increasing crop production. These fungi have proven to increase crop yields by improving germination, seedling vigor, plant growth, root morphogenesis, photosynthesis, and flowering through either a direct or indirect mechanism. The mechanisms of PGPF involve solubilizing and mineralizing nutrients for easy uptake by plants, regulating hormonal balance, producing volatile organic compounds and microbial enzyme, suppressing plant pathogens and ameliorating abiotic stresses. Successful colonization is an intrinsic factor for most PGPF to exert their beneficial effects on plants. A certain level of specificity exists in the interactions between plant species and PGPF for root colonization and growth promoting effects. There is a gap between the number of reported efficacious PGPF and the number of PGPF as biofertilizer. Efforts should be strengthened to improve the efficacy and commercialization of PGPF. Hence, this chapter summarizes valuable information regarding the application and mechanisms

(PGPF) for Phytostimulation

**Keywords:** seed germination, seedling vigor, root morphogenesis, yield,

The world's population exceeded ~7 billion just after 2010, and still continues to grow fast. Roughly, 83 million people are added to the world's population every year and with this pace of growth, the global population is projected to reach around 9.7 billion by 2050, ~24% higher than today [1]. In order to feed this large population, crop production must increase by approximately 25–70% above current production levels [2]. Intensification of agriculture is considered a potential solution. By relying on intensive use of fertilizers, pesticides and other inputs, agricultural intensification increases the productivity of existing farmland and delivers more food to the added population. However, the chemical-based crop

*Md. Motaher Hossain and Farjana Sultana*


*3.1. General Experimental Procedures*

Optical rotation was measured using a JASCO P-2000 polarimeter (Easton, MD, USA), UV/Vis data were obtained using a Beckman DU800 spectrophotometer (Brea, CA, USA), and IR spectra were recorded on a ThermoScientific Nicolet 6700 FT-IR spectrometer (Waltham, MA, USA). NMR experiments were conducted using a JEOL ECZ 500 NMR spectrometer (Akishima, Tokyo, Japan) equipped with a 3 mm inverse probe (H3X), a Bruker AVANCE III 600MHz NMR with a 1.7 mm dual tune TCI cryoprobe (Billerica, MA, USA), and a Varian VX500 (Palo Alto, CA, USA). NMR data were processed using Mestrenova (Mestrelab, Santiago de Compostela, Spain) and TopSpin (Bruker, Billerica, MA, USA). NMR data were recorded in CDCl3 and referenced to the solvent peak (7.260, 77.160). For the low-resolution LC-MS/MS analysis, a ThermoFinnigan Surveyor HPLC System (San Jose, CA, USA) with a Phenomenex Kinetex 5 μm C18 100 × 4.6 mm column (Torrance, CA, USA) coupled to a ThermoFinnigan LCQ Advantage Max Mass Spectrometer (San Jose, CA, USA) in positive ion mode was used. Samples were analyzed using one of two linear gradients from 30% CH3CN + 0.1% formic acid to 99% CH3CN + 0.1% formic acid in H2O + 0.1% formic acid at a flow rate of either 0.6 mL/min or 0.7 mL/min over 32 min or 30 min, respectively. Samples were run at a concentration of 1 mg/mL, with concentrations increased up to 4 mg/mL in situations where the peak intensities were insufficient. For the HiRes-ESI-MS analysis, an Agilent 6230 time-of-flight mass spectrometer (TOFMS) (Santa Clara, CA, USA) with Jet Stream ESI source was used. For HiResMS2 fragmentation data, a ThermoScientific Orbitrap XL mass spectrometer (Waltham, MA, USA) with direct infusion of the sample into the Thermo IonMax electrospray interface was used.

Compound isolation was performed using two semi-preparative HPLCs: a Thermo Scientific Dionex UltiMate 3000 HPLC (Waltham, MA, USA) system with automated fraction collector, a Waters HPLC system with 1500 series pumps (Milford, MA, USA), and a 996 photodiode array detector with manual fraction collection. HPLC separation was performed using a Phenomenex Kinetex 5 μm C18 10 × 150 mm column (Torrance, CA, USA) and reverse phase gradients of acetonitrile in H2O, with both solvents containing 0.1% (*v*/*v*) formic acid. HPLC grade organic solvents and Millipore Milli-Q system (Burlington, MA, USA) purified water were used.

All reagents, catalysts, and solvents used for the synthetic experiments were purchased in their purest and driest form. All experiments were carried out under an inert atmosphere (Ar) unless otherwise specified.

National Cancer Institute (NCI) H460 hypotriploid human cells [American Type Culture Collection (ATCC) HTB-177] and RAW 264.7 murine macrophages (ATCC TIB-71) were purchased from the ATCC (Manassas, VA, USA).