The formation of rubber-producing cortical parenchyma cells in guayule (Parthenium argentatum Gray) by low temperature

A biochemical and ultrastructural analysis of rubber biosynthesis in Parthenium argentatum Gray in the Chihuahuan Desert

“…With the subsequent demonstration ( Fig. 1) (Benedict et al, 2010) that exposing guayule plants to several months of 7 • C in growth chambers promoted the formation of rubber-producing cortical parenchyma with a dense cytosol containing chloroplasts, mitochondria and a population of rubber particles. It is clear that it is the low temperature in these experiments that induces the structural changes in the cortical parenchyma that support rubber biosynthesis.…”

“…Electron photomicrographs of crosssections of the basal part of the stems from 10-month-old plants sampled in January show undifferentiated rubber-producing cortical parenchyma with partially digested cytosol containing a high population of rubber particles and a more advanced formation of central vacuoles with a tonoplast (Fig. 9) (Benedict et al, 2010). The cells at the base of new stems formed during the fall and winter of the desert develop from the undifferentiated cortical parenchyma near the apex of the stems exposed to low temperatures.…”

“…10 (unpublished) of the epithelial cell lining a resin duct is from the same thin sections of the stem cross-sections from plants showing rubber-producing cortical parenchyma (Benedict et al, 2010). This undifferentiated epithelial Reprinted from Benedict et al (2009). cell, induced by the low temperatures, is similar to the undifferentiated epithelial cells among the epithelial cells lining the resin ducts in guayule stems reported by Gilliland and van Staden (1983) and Backhaus and Walsh (1983), and consists of a high population of rubber particles in a central cytosol with no central vacuole or tonoplast.…”

“…Gilliland and van Staden (1983) detected rubber particles in the central cytosol of epithelial cells lining the resin ducts of guayule during the winter months in South Africa. Benedict et al (2010) demonstrated that in guayule plants exposed to the low temperatures of the Chihuahuan Desert, rubber particles were found in the central cytosol of undifferentiated cortical parenchyma.…”

“…An electron photomicrograph of a cortical parenchyma cell from a crosssection at the stem base from guayule plants grown in the Chihuahuan Desert and examined in January, 9570×.Reprinted fromBenedict et al (2010).…”