ABSTRACT
Brinjal (Solanum melongena L.) is one of the most common and known rich source of vitamin B1 (Thiamin), dietary fibre, manganese, niacin (vitamin B3), copper, vitamin B6 (pyridoxine), folate (vitamin B9), potassium, Vitamin K. Brinjal cultivation is affected by several pests and diseases. Sclerotinia blight is one of the most destructive diseases of brinjal caused by Sclerotinia sclerotiorum (Lib) de Bary. Under the present investigation two isolates of Fluorescent Pseudomonads (FLPs) viz., FLP-Brinjal 2020-1 and FLP-Brinjal 2020-2, were evaluated against Sclerotinia sclerotiorum (SCL)under in vivo and in vitro conditions using dual culture, inverted plate assay. FLP-Brinjal 2020-2 gave maximum inhibition over the control followed by FLP-Brinjal 2020-1 against the pathogen in in vitro condition. Experiments conducted in pluck trays indicated that FLP-Brinjal 2020-2 was superior with least sclerotinia blight incidence (20.53%).The identity and diversity among the FLP isolates were examined by sequence analysis of 16s rRNA gene. The gene was amplified by PCR using primers pair, 27 F/1492 R. Amplified DNA products were sequenced and analysed by BLAST (BLASTn) programme at NCBI database for species identification. Among the 10 FLPs isolates assessed 9 were found to have maximum similarity with Pseudomonas aeruginosa. FLP 2020-2 and FLP 2020-1 were found to be Pseudomonas fluorescence which is in confirmation with the morphological observations. Significant diversity among the isolates was observed when dendrogram of the sequence was plotted using CLUSTAL W.
ABSTRACT
Aims@#This study aimed to isolate and evaluate the indigenous fluorescent Pseudomonas spp. with bio-control potential against Rhizoctonia solani and promoting growth in chilli seedlings. @*Methodology@#A total of 120 fluorescent bacterial were isolated from the healthy chilli rhizosphere soil from the seven major chilli cultivation localities in Terengganu, Malaysia. Only 115 Gram negative fluorescent isolates were further invitro screened for antagonistic activities against R. solani and plant growth-promoting properties. The 50 most effective fluorescent Pseudomonads antagonist against R. solani with minimum percentage inhibition of radial growth (PIRG) of 65% were selected. Hierarchical cluster analysis was further conducted with two dendrograms derived from SPSS Statistic 20 to facilitate the comparison between these 50 isolates for antagonistic and growth-promoting properties. A total of 40 fluorescent isolates within the most potential cluster were further selected and identified using 16S rRNA sequencing. Thirty four fluorescent isolates were identified as Pseudomonas spp. and six isolates as Burkholderia spp. The top 13 ranked fluorescent Pseudomonas spp. from the scoring index were evaluated for seed germination and vigor index in chilli seedlings. There was no significant difference in germination rate between fluorescent Pseudomonas inoculated with control. However, vigor index of chilli seeds pre-inoculated with fluorescent P. putida (B5C1), P. aeruginosa (B3C56) and P. putida (B5C7) were significantly increased with 4684.9, 4657.3 and 4401.0 over control (P ≤ 0.05).@*Conclusion, significance and impact of study@#These selected fluorescent isolates: P. putida (B5C1), P. aeruginosa (B3C56) and P. putida (B5C7) have the potential to be developed as biofungicide against R. solani and as growthpromoter in chilli production system.