Poster: Mineral nutrition

Abs # 199: Identification of Phosphate Starvation-induced Genes from Tomato Roots by Subtractive cDNA Cloning and Microarray Hybidization

Presenter:	Lin, Shu-I , pcoo2402@gate.sinica.edu.tw
Authors	Lin, Shu-I  (A)   Shieh, Shin-Yun  (A)   Wang, Jhy-Gong  (A)   Cheng, Pei-Wen  (A)   Huang, Wei-Zhou  (A)   Huang, Yu-Ting  (A)   Yuan, Shulung  (A)   Chiou, Tzyy-Jen  (A)
Affiliations:	(A): Institute of BioAgricultural Sciences, Academia Sinica

Phosphorous (Pi) is one of major nutrients to control plant growth and development; however its low availability in many soils often affects crop production. In this study, we intend to identify Pi starvation-induced genes as the first step in understanding the molecular events mediating plant responses to Pi starvation. 903 tomato expressed sequence tag (EST) clones were obtained from a subtractive cDNA library enriched with Pi starvation-induced genes of tomato roots. After sequence analysis, these EST clones represented 499 unique sequences/genes that correspond to 352 TCs and 53 singletons in the TIGR tomato EST database. Interestingly, sequences of 94 unique clones have never been reported in the tomato database and 43 of them are novel since no any sequence clones homology can be found in the GenBank database. A microarray system containing 768 EST clones in which several redundant sequences were excluded was designed to identify the genes specifically induced by Pi starvation. mRNAs isolated from two different batches of root samples treated under Pi sufficient or Pi free nutrient solution for various time points were subjected for microarray hybridization. 326 clones which represent 218 unique genes were identified to be up-regulated more than 2 fold under Pi starvation treatment. The expression of these genes increased along the starvation treatment and decreased when phosphate was replenished back to the nutrient solution, indicating their gene expression was affected by the change of external Pi concentration. These 218 genes were functionally classified into several categories. The expressions of several genes were verified by RNA gel blot analysis. Candidate genes likely involved in regulatory and signaling pathways will be our focuses for further studies.