Changes in gene expression in Arabidopsis shoots during phosphate starvation and the potential for developing smart plants

• Published in: Plant physiology (Bethesda) 2003-06, Vol.132 (2), p.578-596
• Main Authors: Hammond, J.P, Bennett, M.J, Bowen, H.C, Broadley, M.R, Eastwood, D.C, May, S.T, Rahn, C, Swarup, R, Woolaway, K.E, White, P.J
• Format: Article
• Language: English
• Subjects: Acid soils; Agronomy. Soil science and plant productions; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis thaliana; Base Sequence; beta-glucuronidase; Biological and medical sciences; DNA Primers; DNA, Complementary - genetics; Economic plant physiology; enzyme activity; Fundamental and applied biological sciences. Psychology; Gene expression; gene expression regulation; Gene Expression Regulation, Plant; Genes; Genetic Markers; genetic transformation; Glucuronidase - genetics; hydroponics; Leaves; Mineral nutrition; nutrient deficiencies; Nutrient solutions; Nutrition. Photosynthesis. Respiration. Metabolism; phenotypic variation; PHO-like element; Phosphates; Phosphates - metabolism; Phosphorus; plant breeding; Plant growth; Plant physiology and development; Plant Shoots - metabolism; Plants; Polymerase Chain Reaction - methods; promoter regions; reporter genes; Research Papers on Systems Biology/Genomics/Bioinformatics; shoots; SQDI gene; Starvation; sulfolipid synthase; sulfolipids; TATA box; Trace Elements - metabolism; transgenic plants; Water and solutes. Absorption, translocation and permeability
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.103.020941

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 β-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.