Glycine max Transcriptome or Gene expression. Glycine max

The paraveinal mesophyll (PVM) of soybean leaves is a layer of laterally expanded cells sandwiched between the palisade and spongy mesophyll chlorenchyma. The vacuoles of PVM cells contain an abundance of a putative vegetative storage protein, VSP (α, β). VSP is is constitutively produced, but is up-regulated during sink limitation experiments involving flower, fruit, or vegetative bud removal. Soybean vegetative lipoxygenases (Vlx), consisting of 5 isozymes (Vlx, A-D), have been identified as potential storage proteins because they accumulate to high levels with experimental sink limitation and have been co-localized with VSP to the vacuoles of PVM cells. We re-investigated the sub-cellular locations of these enzymes with TEM immuno-cytochemistry. We employed laser micro-dissection to compared RNA expression of PVM cells with mesophyll chlorenchyma cells; and we performed a micro-array analysis of soybean leaf samples representing a time-course, sink-limitation, experiment. We found that none of the Vlx isozymes co-localize with putative storage proteins in PVM vacuoles, and that our sink limitation experiment (typical of those used in the past) induced a strong up-regulation of stress response genes, simultaneous with the up-regulation of the Vlx isozymes. Our findings do not support a storage function for soybean Vlx. The microarray results presented here represent our comparison of gene expression within PVM and palisade mesophyll paraenchyma (PP) cells from mature soybean leaves. For this part of our study both the PVM and palisade parenchyma (PP) cells were isolated from sections of soybean leaves by laser micro-dissection and pressure catapulting (LMPC). Total RNA was isolated from these cells and amplified for microarray analysis. Overall design: Soybean leaves were fixed with a mixture of ethanol and acetic acid, embedded in paraffin and sectioned to provide samples for laser micro-dissection with pressure catapulting (LMPC). Slides were deparaffinized prior to LMPC. A total of six samples were collected: three biological replicates for PVM cells and three replicates for PP cells. After enough cells were collected for each samples, the cells were pooled for RNA extraction. RNA was amplified prior to microarray hybridization using the Whole-Transcriptome Ovation Pico RNA Amplification System from NuGEN Technologies, San Carlos, CA, USA.