The Association of Semisterile-1 in Maize with Two Linkage Groups.
In 1925 there appeared in one of the senior writer’s cultures of maize a few plants producing 50 percent aborted pollen. Subsequent examination of the ears borne by these individuals revealed that they likewise developed only one-half the normal number of seeds. Following BELLING’S (1914) application of the term to a similar condition in Stizolobium, the phenomenon was called semisterility. The pedigreed line to which the
A Second Gene Producing Golden Plant Color in Maize
A second factor influencing the production of golden plant color has been isolated and found to behave as a simple Mendelian recessive. For convenience in nomenclature the original golden producing factor has been designated as golden 1 (g1) and the new factor as golden 2 (g2). The factor pairs for golden 1 and golden 2 have been found to exhibit a complementary action toward one another. G1g1 and G2g2 do not appear to be linked.
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.