Sharma et al.

where as the term plant growth regulators (PGRs)

test, growth at optimum temperature i.e. 4°C, 25°C,

include many synthetic and naturally occurring

37°C and 41°C, fermentative/oxidative metabolism,

compounds. Plant growth regulators as “either

gelatin liquification .

natural or synthetic compounds including microbial

plant growth regulators that are applied directly to a

Screening of isolates for the production plant

target plant to alter its life processes or its structure

growth regulators (PGRS)

to improve quality, increase yields or facilitate

Pseudomonas sp. isolated from the rhizosphere soil of

harvesting” (Nickell, 1982). The production of plant

pear and apple orchards were screened out for the

growth regulators induces additional root hair and

production of plant growth regulators viz., auxins,

lateral root formation (Tine et al., 1979). Thereby

gibberellins and cytokinins. Quantitative estimation

enhancing the plant’s ability to take up nutrients

of auxins was done by colorimetric method (Gordon

from soil and increasing the yield. Production of

and Weber, 1951) with slight modifications i.e. 2 to

different phytohormones like indole-3-acetic acid

3 drops of orthophosphoric acid was added to 2 ml

(IAA), gibberellic acid and cytokinins PGPR can

supernatant and 4 ml of salper reagent (1 ml of 0.5 M

increase root surface and length and promote in

FeCI ₃ in 50 ml of 30 % HCIO ₄ : prepared fresh). The

this way plant development (Kloepper et al., 2007).

gibberellins were estimated calorimetrically by the

Several PGPR and free living rhizobacterial species

method of (Holbrook et al., 1961). Radish cotyledons

are reported to produce IAA and gibberellic acid in

expansion bioassay test was employed (Letham,

the rhizospheric soil and thereby play a significant

1971) for estimation of cytokinins like substances the

role in increasing the root surface area and number

radish seeds ( Raphanus sativus L. cultivars Japanese

of root tips in many plants (Bhattacharya and

white) were germinated in total darkness for 48 h at

Jha, 2012; Salisbury and Ross, 1985). Bacteria like

28° C.

Azospirillum and Pseudomonas sp. produce cytokinins

and gibberellins, in addition to IAA. Cytokinins

Production, purification and characterization of

are a class of phytohormones which are known to

plant growth regulators

promote cell divisions, cell enlargement and tissue

Auxins, gibberellins and cytokinins produced extra

expansion in certain plant parts. Gibberellins are a

cellularly in nutrient broth by Pseudomonas sp. at best

class of phytohormones most commonly associated

optimum conditions i.e. 28° C under shake conditions

with modifying plant morphology by the extension

(90 rpm) after 72 hours. Auxins and gibberellins were

of plant tissue, particularly stem tissue (Salisbury,

extracted from 72 h old cell free culture supernatant

1994) . In this paper, production of plant growth

with diethyl ether and ethyl acetate respectively.

regulators and their estimation along with their

Pooledfractionswereevaporatedinrotaryevaporator

respective methods, by fluorescent Pseudomonas

at 40° C. Similarly cytokinins were extracted from the

strains isolated from rhizospheric soil has been

supernatant with diethyl ether and extracted with

explored in in vitro on broccoli and cabbage for

equal volume of n-butanol (Mahadvan and Sridhar,

stimulation of callus formation and root formation

1986). Pseudomonas sp. An-1-kul and An-13-kul

has been studied.

were grown in nutrient broth for 72 h. at 28 + 2° C

Materials and Methods

under shake conditions (90rpm). Supernatants were

prepared by centrifugation of cultures at 10,000 rpm

Fluorescent Pseudomonads sp. were isolated

for 20 minutes and were stored at 4° C.

from soil samples collected from the normal and

replant sites of apple and pear rhizosphere. Total

Molecular

characterization

of

fluorescent

30 Pseudomonas strains were isolated and further

Pseudomonas sp. by 16S rRNA technique

identified on the basis of morphological biochemical

GenomicDeoxyribonucleicacid(DNA)wasextracted

and physiological tests viz., catalase test, oxidase

with DNA isolation kit (Bangalore GeNei), and the

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