title: Changes in gene expression in Arabidopsis shoots during phosphate starvation and the potential for developing smart plants.
abstract: Our aim was to generate and prove the concept of "smart" plants to monitor plant phosphorus (P) status in Arabidopsis. Smart plants can be genetically engineered by transformation with a construct containing the promoter of a gene up-regulated specifically by P starvation in an accessible tissue upstream of a marker gene such as beta-glucuronidase (GUS). First, using microarrays, we identified genes whose expression changed more than 2.5-fold in shoots of plants growing hydroponically when P, but not N or K, was withheld from the nutrient solution. The transient changes in gene expression occurring immediately (4 h) after P withdrawal were highly variable, and many nonspecific, shock-induced genes were up-regulated during this period. However, two common putative cis-regulatory elements (a PHO-like element and a TATA box-like element) were present significantly more often in the promoters of genes whose expression increased 4 h after the withdrawal of P compared with their general occurrence in the promoters of all genes represented on the microarray. Surprisingly, the expression of only four genes differed between shoots of P-starved and -replete plants 28 h after P was withdrawn. This lull in differential gene expression preceded the differential expression of a new group of 61 genes 100 h after withdrawing P. A literature survey indicated that the expression of many of these "late" genes responded specifically to P starvation. Shoots had reduced P after 100 h, but growth was unaffected. The expression of SQD1, a gene involved in the synthesis of sulfolipids, responded specifically to P starvation and was increased 100 h after withdrawing P. Leaves of Arabidopsis bearing a SQD1::GUS construct showed increased GUS activity after P withdrawal, which was detectable before P starvation limited growth. Hence, smart plants can monitor plant P status. Transferring this technology to crops would allow precision management of P fertilization, thereby maintaining yields while reducing costs, conserving natural resources, and preventing pollution.
authors.affiliation: Horticulture Research International, Wellesbourne, Warwick CV35 9EF, United Kingdom.
authors.forename: John P
authors.initials: JP
authors.lastname: Hammond
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Bennett
authors.forename: Helen C
authors.initials: HC
authors.lastname: Bowen
authors.forename: Martin R
authors.initials: MR
authors.lastname: Broadley
authors.forename: Dan C
authors.initials: DC
authors.lastname: Eastwood
authors.forename: Sean T
authors.initials: ST
authors.lastname: May
authors.forename: Clive
authors.initials: C
authors.lastname: Rahn
authors.forename: Ranjan
authors.initials: R
authors.lastname: Swarup
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Woolaway
authors.forename: Philip J
authors.initials: PJ
authors.lastname: White
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics; D001483:Base Sequence; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005819:Genetic Markers; D005966:Glucuronidase / Q000235:genetics; D010710:Phosphates / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods; D014131:Trace Elements / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D005819:Genetic Markers; D010710:Phosphates; D014131:Trace Elements; D005966:Glucuronidase