Sharma et al.

150% of shoot regeneration and 2 shoots per 4 explant

90-95percent survival rate of root regeneration in

(2/4 shoots). In comparison to our study appropriate

plant (Ali et al., 2009). The highest percentage of

effective concentration of cytokinins might have not

hypocotyl explants of soy bean producing shoot

been produced by inoculated PGPR P. putida strains

(96.67%) and the highest mean number of shoots

in the study. This difference may also be due to the

produced per hypocotyl explant (6.03) were obtained

potential of strains i.e. strain variation and also due

on 3 mgl –1 BAP. While the highest percentage of shoot

to use of partially purified cytokinins.

tip explants producing shoot (100%) and highest

Rashid and Bal (2010) reported that direct

number of shoot produced per shoot tip explant (3.76)

regeneration was significantly influenced by the

were recorded on5 mgl –1 BAP. It has been reported

genotype, hormone and concentration. They

that use of BAP (6- benzyl amino purine) at 3 mg –1

obtained maximum shoot regeneration and number

and 5 mg –1 as the most suitable concentration for the

of shoots per explant from hypocotyl on MS medium

callus formation and shoot initiation (Ravanfar et al.,

supplemented with kinetin (0.5 mg –1 ) and BAP (0.5

2009). El-Barkry (2002) observed maximum number

mg –1 ). Madhulatha et al., (2006) reported that out of

of shoots on MS basal medium supplemented with

the various combinations of cytokinins and auxins

2.0mg –1 BA and 0.20 mg –1 IAA in five cultivars from

tried, MS medium containing 2.5 mg –1 BAP + 0.5

cotyledon explants.

mg –1 IAA was the best combination for multiple

From this experimental study, it can be concluded

shoot induction. The direct optimization of shoot

that a tissue culture based bioassay is important

regeneration protocol from hypocotyl explant

and valuable for evaluation of putative PGPRs and

for cotton using thidiazurm (TDZ and 0.08mg –1 ),

for their products like plant growth regulators and

Naphthalene acetic acid (NAA 0.01mg –1 ) and silver

further detailed work is necessary to define the

nitrate (5.1mg –1 ) was done (Ouma et al., 2004). It

conditions under which PGPR activity and their

was reported that auxins exerts primary role in

products can be detected. Further experimentation

root formation by its involvement in successive and

should be under taken to determine if its PGPR

interdependent phase (Bellamine et al., 1998). Some

activities is related to PGRs production in situ . The

finding showed that differentiation of phloem ray

fluorescent Pseudomonas sp. are plant beneficial

parenchyma cells into root primordia depends upon

rhizobacteria with all the direct and indirect plant

the type and concentration of auxins (Sabatini et al.,

growth promoting activities like plant growth

1999). Further it has been reported that differentiating

regulatorssuchasauxins,cytokininsandgibberellins.

cells require the most appropriate auxins to become

Plant growth regulator production is an important

competent to respond to the organogenic signal by

secondary metabolite of fluorescent Pseudomonas as

(Blakesley and Chaldecott, 1997). The effect of auxins

it directly involves in the growth and development

onrootingwasfoundpromotoryatlowconcentration

of plant root, shoots. It is worth to note that strains

and inhibition at supra-optimal concentration

belonging to Pseudomonas aeruginosa are considered

(Sugiyama, 1999). IBA (indole butyric acid) and

safe for use in biotechnological applications.

naphthalene acetic acid (NAA) hormone tested for

maximum percentage of rooted shoots, root number,

Acknowledgements

root length and quality of roots (Chanway et al.,

The authors are highly thankful to the department

1989). Successful rooting was achieved by placing the

of Basic Science (Microbiology) and Biotechnology

shoots onto MS basal medium supplemented with

of Dr Y S Parmar University of Horticulture and

0.20 mg –1 NAA (Sharma and Srivastava, 2014). IBA

Forestry, Nauni, Solan (HP)-173230, India to carry

at 1.5mg –1 showed maximum root initiation (86.67%

out the present work.

shoots), 5.03 numbers of roots per rooted explant and

4, 95 cm root length. Earlier it has also been reported

756