Seeking transformation markers: an analysis of differential tissue proteomes on the rice germplasm generated from transformation of Echinochloa crusgalli genomic DNA.

The transformation of distally related genomic DNAs into plant was proposed as a novel technique to breed new cultivars. For example, a restorer rice line, RB207, was successfully developed and stabilized through the transformation of genomic DNAs of Echinochloa crusgalli (E. crusgalli) into a rice line, R207. Although the phenotypes of this variant line are apparently different from its receptor, the molecular bases are not elucidated yet. Herein, we have systematically studied the differential proteomes from the tissues of E. crusgalli, R207, and RB207 in an attempt to find an explanation regarding the phenotypic changes of RB207. The 2-DE method was employed to separate the leaf and embryo proteins of these plants followed by protein identification with mass spectrometry. In the leaf, 953 +/- 15, 1084 +/- 11, and 1091 +/- 11 silver-stained spots were detected, whereas in the embryo, 986 +/- 3, 884 +/- 10, and 892 +/- 14 spots were found from E. crusgalli, R207, and RB207, respectively. In comparison to the 2-DE images of the two rice lines, which showed many similarities, the ones of the E. crusgalli and rice were found to be so different that they were incomparable. There were some differentially expressed 2-DE spots between the two rice cultivars, 72 in leaf and 53 in embryo, respectively. The results of protein identification suggested that, regardless of leaves or embryos, none of the E. crusgalli genes were encoded in the new rice cultivar, RB207. The fact that 60% of the differentially expressed spots between R207 and RB207, however, were verified as the proteins involved in metabolism and photosynthesis makes a rather convincing argument that the DNA fragments transferred from E. crusgalli to rice are responsible for exerting the unknown influence to the expression of rice genes.