BALLACHANDA, D.

CAO, A.

JAIN, A.

KARTHIKEYAN, A. S.

RAGHOTHAMA, K. G.

RAMAIAH, M.

VASCONCELOS, M. J. V.

WAND, J.

English

Repository Open Access to Scientific Information from Embrapa

Phosphorus is one ofthe most limiting plant nutrients in the soil. Lack of available phosphatein the rhizosphere has severely reduced crop yields in vast stretches of acid soils in the tropics.Deficiency of phosphorus has resulted in numerous adaptations by plants to obtain and utilize thenutrient efficiently. The complex adaptation processes involve changes in the expression ofhundredsof genes as indicated by microarray analysis. The genes that are altered during phosphate deficiencycode for many functional and structural components. Many genes presumed to be associated withsignal transduction pathways are altered during phosphate deficiency. Microarry data was furtherconfirmed by Northem blot and RT-PCR analysis. Genes representing transcription factors such asWRKY, zinc finger binding factors, MYB exhibit phosphate starvation-mediated enhancement inexpression. The coding sequences ofthese transcription factors were cloned into appropriate vectorsto produce transgenic Arabidopsis either over-expressing or suppressing the expression of genes.Over-expression and RNAi knockout ofsome ofthe transcription factors showed distinct changesin plant growth in response to altered phosphate concentration in the medium.It is not surprising to know that phosphate deficiency induced signaling is quite complexand multiple effectors are involved in the processo Characteristic changes in root morphologyduring phosphate starvation points to the involvement of plant hormones such as auxin and cytokinins.Addition ofthese hormones to growth media not only altered root morphology but also suppressedthe expression of some of the phosphate starvation induced genes. In addition, sugar also plays animportant regulatory role in phosphate starvation mediated responses. Input of sugar is not onlyrequired for initiation of changes in gene expression but also for many of the root architecturalmodifications associated with phosphate deficiency. Among the sugars (sucrose, glucose and fructoseetc.) tested, sucrose had the most noticeable effect on gene expression. These data strongly point tothe involvement of sugar in phosphate starvation mediated responses in plants. At present it is notclear how carbon and phosphate are interacting at the level of signal transduction.Several genetic screens based on reporter gene expression and ionomics are being used toisolate mutants showing altered gene expression and phosphate content. T-DNA tagged and fastneutron bombardment generated mutants of Arabidopsis thaliana are being screened for mineralnutrient composition using ICP-MS. Plants expression the reporter gene luciferase under theregulation of promoter of high affinity phosphate transporter was generated by Agrobacteriummediated transformation. These plants were used for generating T-DNA tagged population. T-DNA tagged population is being screened for altered response ofplants to phosphate deficiency orsufficiency. Mutants having altered phosphorus content and/or altered reporter gene expression aresubjected to a battery of genetic and molecular tests. Characterization ofthese mutants should leadto molecular determinants regulating phosphate uptake and utilization by plants.Molecular regulation of phosphate starvation responses in plantsRaghothama, K.G.; Karthikeyan, A.S.; Jain, A.; Ramaiah, M.; Vasconcelos, M.1.V.; Ward, 1.;Cao, A.; Ballachanda, D.Department ofHorticulture and Landscape Architecture, Purdue University, West Lafayette, IN4790786 Proceedings of 3n1 International Symposium on Phosphorus Dynamics in the Soil-Plant Continuum

Molecular regulation of phosphate starvation responses in plants.

http://www.alice.cnptia.embrapa.br/bitstream/doc/489643/1/Molecularregulation.pdf

Molecular regulation of phosphate starvation responses in plants.

Abstract

Similar works

Full text

Available Versions

Repository Open Access to Scientific Information from Embrapa