A Sec14-like protein regulates tocopherol content in transgenic tomato plants.

BERMUDEZ L, DE GODOY F, ALMEIDA J, OTAIZA S, ASIS R, CARRARI, ROSSI M

Encuentro; Gordon Research Conference; 2011

SEC14-like proteins have been identified in all kingdoms and showed to be involved in membrane trafficking, regulation of phospholipid metabolism and phosphoinositide signaling pathways. Based on metabolic QTL mapping data from a S. pennellii introgression lines population in the genetic background of S. lycopersicum (cv. M82), our group has identified a SEC14-like protein co-localizing with a α-tocopherol QTL on chromosome 9. We present here results on the functional characterization of this protein in tomato, including: sequence analyses, expression profiles and sub-cellular localization experiments for both alleles. Moreover, iRNA tomato plants showed impairment in the photosynthetic performance and revealed alterations in sugars and tocopherol contents. Source leaves of independent transgenic lines presented ~0.3- to 0.5 and ~0.3- to 0.6-fold lower levels of α-tocopherol and γ-tocopherol, respectively, than those in control plants. In addition, the levels of total tocopherol in iRNA-SEC14 fruits decreased up to 0.2-fold and 0.5-fold, as compared to the control fruits. Moreover, expression analyses of the genes encoding for VTE core pathway enzymes (VTE1, VTE2, VTE3, VTE4, VTE5 and HPPD) showed no altered profiles in the transgenic lines. The exception is the case of vte5 gene which showed differential expression in both, leaves and red fruits, suggesting that a transcriptional regulatory point operates on this gene and allowed us to propose that the tomato SEC14-like protein participates in the control of tocopherol biosynthesis in tomato plants.