http://jurnal.permi.or.id/index.php/mionline/article/view/190

Abstract

Endophytic bacteria colonize healthy plant roots without causing apparent disease. More convey stress tolerance, induce systemic resistance, recently, endophytic bacteria have gained attention due to their interesting features related to plant growth and health stimulation. Studies on endophytic bacteria have been conducted. Some of the bacteria are known to increase nutrient availability, produce growth hormones, or deter plant pathogens (Hallmann et al. 1997; Buchenauer 1998). Several reports demonstrated that endophytic bacteria are plant-associated bacteria that colonize and persist in various healthy plants, such as fruits, vegetables, stems and roots (Mclnroy and Kloepper 1995; Sturz et al. 1997). Bacterial endophytes can be isolated from surface-sterilized plant tissue or extracted from internal plant tissue. Endophytic microorganisms enter plant tissue primarily through the root zone; however, aerial portions of plants, such as flowers, stems, and cotyledons, may also be used for entry (Quadt-Hallmann and Kloepper 1996). Specifically, the bacteria enter tissues via germinating radicles, Endophytic bacteria have gained attention due to their interesting features related to plant growth and health stimulation. The objective of this research was to determine the populations and spectrum of indigenous root endophytic bacteria from tomato (Lycopersicon esculentum) and the biocontrol activity of the bacteria for plant protection. The isolation procedure of these endophytic bacteria was done using surface-sterilization method using alcohol and sodium hypochlorite (NaOCl). General medium trypsic soy agar (TSA) was used as the growth medium for isolation. The total population density of endophytic bacteria recovered from tomato roots ranged-1 from 1.0 to 4.4 (in log scale) CFU g fresh root weight. A total of 564 strains of endophytic bacteria were isolated 10 from tomato plants grown in West Java, Indonesia. Endophytic bacterial strains were identified based on their fatty acid profile using FAME-GC-MIDI system. Fifty species and 32 genera of endophytic bacteria were found in association with tomato root. The most abundant endophytic bacterial genera were Bacillus spp and Pseudomonas spp. One hundred and eighty one bacterial strains were tested for their in vitro antagonism towards Rhizoctonia solani, Fusarium oxysporum f.sp. radicis-lycopersici, and F. oxysporum f.sp. lycopersici. Fourteen strains showed antagonism against R. solani, nine strains against F. oxysporum f.sp. radicis-lycopersici and seven strains against F. oxysporum f. sp. lycopersici. The close relationship between endophytic bacteria and their hosts make them ideal candidates for biological control and plant growth promotion.