@article{krings_jordan_culatta_szakacs_wilson_2020, title={Annual Signature in the Taproots of Echinacea laevigata and E. pallida (Asteraceae, Heliantheae)}, volume={85}, ISSN={["1938-4386"]}, DOI={10.2179/0008-7475.85.1.199}, abstractNote={ABSTRACT The annual signature of the roots of relatively few species of North American herbaceous perennials is known, which is unfortunate, considering the potential contributions an increased understanding of age structure of populations of such species could represent. To help fill this gap, we briefly communicate here results of recent work on Echinacea laevigata and E. pallida (Asteraceae, Heliantheae), both species of conservation concern in the eastern United States. Analysis of cross-sections of individuals of known age of both species revealed an annual signature consistent with that reported for other herbaceous perennials, namely the development of clusters of vessels with conspicuously large diameters, marking annual spring root growth, followed by vessels of reduced diameter in the remainder of the year.}, number={1}, journal={CASTANEA}, author={Krings, Alexander and Jordan, Chad and Culatta, Katherine and Szakacs, Alexandria and Wilson, Greg}, year={2020}, month={May}, pages={199–204} }
 @article{jordan_shen_hanley-bowdoin_robertson_2007, title={Geminivirus-induced gene silencing of the tobacco retinoblastoma-related gene results in cell death and altered development}, volume={65}, ISSN={["1573-5028"]}, DOI={10.1007/s11103-007-9206-3}, abstractNote={The retinoblastoma-related protein (RBR) is required for cell cycle control and differentiation and is expressed throughout the life of plants and animals. In this study, the tomato golden mosaic virus (TGMV) geminivirus vector was used to silence NbRBR1 in Nicotiana benthamiana by microprojectile bombardment into fully developed leaves. Similar to previous results using agroinoculation of a tobacco rattle virus silencing vector [Park et al. (Plant J 42:153, 2005)], developmental defects caused by disruptions in cell size and number were seen in new growth. Leaf midvein cross-sections showed tissue-specific differences in size, cell number, and cell morphology. While cortical cell numbers decreased, size increased to maintain overall shape. In contrast, xylem parenchyma cells increased approximately three fold but remained small. Normally straight flowers often curved up to 360 degrees without a significant change in size. However, the most striking phenotype was cell death in mature cells after a delay of 3-4 weeks. Trypan blue staining confirmed cell death and demonstrated that cell death was absent in similarly treated leaves of wild type TGMV-inoculated plants. Quantitative RT-PCR confirmed that the mature TGMV:RBR-inoculated leaves still maintained reduced accumulation of RBR transcript at 4 weeks compared to controls. The results suggest that either inappropriate activation of the cell cycle is lethal in plants or that RBR has other functions, unrelated to the cell cycle. The results also demonstrate that continual transcription of RBR is necessary for cell survival.}, number={1-2}, journal={PLANT MOLECULAR BIOLOGY}, author={Jordan, Chad V. and Shen, Wei and Hanley-Bowdoin, Linda K. and Robertson, Dominique}, year={2007}, month={Sep}, pages={163–175} }