Enhanced phosphorus uptake in transgenic

tobacco plants that overproduce citrate

Presented by group 1st

Out lines

• Role of Phosphorus.

• Problem of Phosphorus in Alkaline soil.

• citrate synthase [Pseudomonas aeruginosa], ACCESSION NP_250271, 1.7kbp.

• 35S CaMV Promoter

• Experimental Results

Abstract

• Phosphorus a most important nutrients

• Forms insoluble compounds

• Not available to plants

• 30 m tons of P fertilizer applied every year

• development of novel plant varieties

• That over produce organic acid

Introduction

• P an important nutrient after N

• Produce ATP, Nucleic acid and phospholipids

• Extremely reactive

• Only available at a narrow range pH values

• Highly immobilized

• React with AL, Fe and CA ,Mg in acid and basic pH respectively

• Required for enhancement of reproductive part

• Novel plants can reduce the use of synthetic p

• Citrate exudation can increase uptake of p in alkaline soil

• Citrate can displace P from insoluble complexes

• Increase 2 to 3 fold uptake of soil P

Experimental protocol

• Plant selection

• Biochemical analysis by srere method

• P-soluble experiments.

• Use of hydroxyapatite

• P determinations

• In vitro phosphate uptake experiments

• Rhizospheric changes in transgenic plants.

• Mycorrhizal colonization experiments.

Results & discussion

• Transgenic plants of tobacco were produced

• Having expression of citrate over producing sequence(Pseudornonas aeruginosa)

• 35s CaMV promoter

• By Agrobacterium-mediated transformation

• Analysis showed that citrate-overproducing lines (CSb-4 and CSb- 18)

• Produce 3 to 4 fold more citrate than control line

conti…

• CSb lines produce more yield in alkaline soil

• Control line unable to produce flower

• Experiment was conducted to confirm that it is due to citrate over production or not

• Plant were grown in control environment

• 3 treatments of water soluble P was applied (NaH2P04a t 22,44, and 108 mg kg-' soil).

• Analysis was made after 30 days and at flowering

• Significant differences between CSb and control

Conti…

• At high level of P no significant difference

• P concentration of leaves were determine

• To ensure that it was due to P acquisition

• Significant differences at flowering

• Other experiment was made

• Two treatment of soluble hydroxyapatite applied

• CSb lines produce more fruit biomass

• It was due to citrate excretion

Conti…

• For confirmation

• Plant grown in media having insoluble p

• Plants were grown in presence & absence of 1mM citrate

• No difference in CSb and control having citrate in media

• It indicate that citrate dissolve the insoluble P

• It was because of

• Rhizosphere acidification

• Reduction of Ca by the formation of calcium citrate

Conti…

• Symbiosis with mycorrhizal fungi also help in P acquisition

• It has additive effect with citrate in p uptake

• Our results demonstrated the importance of transgenic plants in acquisition of soluble P

• Which help to uptake reserve P

• We can meet P requirement by little application