Microarray Detection Call Methodology as a Means to Identify and Compare Transcripts Expressed within Syncytial Cells from Soybean (Glycine max) Roots Undergoing Resistant and Susceptible Reactions to the Soybean Cyst Nematode (Heterodera glycines)
Figure 1
Life cycle of H. glycines. Cysts, encasing the eggs, are able to remain dormant in the soil for years. At some point, the eggs hatch. The second-stage juveniles (J2s) migrate toward the root and burrow into it. The infective J2s (i-J2s) then migrate toward the root stele. A stylet emerges from the anterior end of the nematode. The nematode selects a pericycle cell or neighboring root cell, for its feeding site. The i-J2 then presumably releases substances that then cause major changes in the physiology of the root cell. Those root cells (yellow) subsequently fuse with neighboring cells (light blue), producing a common cytoplasm. The repeated cell fusion events produces a syncytium (orange) that contains approximately 200 merged root cells and serves as the H. glycines feeding site. After the establishment of the syncytium, male nematodes feed for several days. Feeding proceeds until the end of their J3 stage. Meanwhile, the males become sedentary. Subsequently, the males stop feeding, followed by a molt into vermiform J4 males. The males burrow out of the root in preparation for copulation. In contrast to the males, the females become and remain sedentary after the establishment of their feeding site. The female nematodes then increase in size while undergoing both J3 and J4 molts. The J4s then mature, becoming adult feeding females. Ultimately, the female develops into the cyst that encases the eggs. (a) Cysts (dark red) with eggs (white) hatch. (b) Second-stage juveniles (J2) (gray) hatch and migrate toward the root. (c) The J2 nematodes burrow into the root and migrate toward the root stele (dark gray). (d) Feeding site selection (yellow). (e) i-J2 nematodes molt into J3 and then J4. The female is shown here in red. During this time, the original feeding site (yellow) is incorporating adjacent cells (magenta) via cell wall degradation and fusion events. Meanwhile, the male discontinues feeding at the end of its J3 stage. (f) The male and female J4 nematodes mature into adults. By this time, the feeding site has matured into a syncytium (green) as shown here where the female is actively feeding. The vermiform male (blue) migrates out of the root and subsequently copulates with the female (red). (g) After 30 days, the female is clearly visible externally because its body emerges from the root tissue. The figure is adapted from Klink et al. [11].
