Abstract

Role of Salicylic Acid in Bacterial Root Colonization in Rice Varieties

Seema Garcha, , Punjab Agricultural University

Plant–microbe interaction is an important aspect in rhizosphere and components identified in root exudates play important role in these interactions. Salicylic acid (SA) is plant defense hormone and is one of the compounds present in root exudates. It helps in organization of root flora in plant. In present study attempt was made to check the role of SA in bacterial root colonization in Basmati varieties: PB-3, PB-5 and PB-1121 in comparison with wild variety of rice crop. Tissue culture generated seedlings was transplanted in field. The estimation of SA was carried out using HPLC- Agilent 1260 infinity 2 HPLC Series and microfloral profiling was done as per standard microbiological methods at different stages (at the time of transplant, 60 DAT, 90 DAT and at harvest) in the development of rice plant. Amount of macronutrients present in field soil were 0.39% of Nitrogen, 75.12 Kg/hectare of Phosphorous and 163.09 Kg/hectare of Potassium. In Basmati varieties, salicylic acid content was found to be highest at 60 DAT. The increase in SA content was due to invasion of bacteria present in rhizosphere as plant was transplanted in the field. The microflora was also increased at 60 DAT and at this stage root flora was established. The SA content was low at 90 DAT as no disease was found in Basmati varieties. At harvest stage the SA level increased because of ageing of plant which kept defense system at high alert. Among the three Basmati varieties PB-3 (1.01 µg/g) contained higher level of salicylic acid at 60 DAT. In wild variety, the pattern was different from Basmati varieties. In this the SA level was maximum at 90 DAT and its concentration was 0.244 µg/g which further increased to 0.280 µg/g at harvest stage. The microfloral count was increased at 60 DAT and 90 DAT in comparison to the time of transplant and it indicates establishment of root flora at this stages. KEYWORDS: Plant-microbe interaction, plant defense system, root exudates, root endophytic microbes and salicylic acid.