Question

Perennial desert shrubs of the genus atriplex are typically dioecious; they consist of separate male and female plants. Species within this genus also have varying levels of ploidy. Four-wing saltbush (A. canescens) and salt sage (A. tridentata) are widespread species throughout the American West. Both are fully fertile. In 1979, Stutz et al. (Amer. J. Bot. 66:1181–1193) reported the discovery of an isolated female four-wing saltbush plant surrounded by a large population of salt sage near the south shore of the Great Salt Lake. Chromosome counts in the somatic cells of the salt sage population consistently yielded 2n = 54. Seed collected from the isolated female four-wing saltbush plant were grown in a garden. The plants that arose from the seeds were sterile and had 45 chromosomes in the somatic cells.

Answer 1

Atriplex species, such as four-wing saltbush and salt sage, are dioecious desert shrubs with varying ploidy levels. An isolated case of hybridization between these species resulted in sterile offspring with a unique chromosome count, highlighting the complexities of plant reproduction and hybrid viability.

Step-by-step explanation:

Perennial desert shrubs of the genus Atriplex, such as the four-wing saltbush (A. canescens) and salt sage (A. tridentata), are important components of the American West's ecosystem. These dioecious shrubs, having separate male and female plants, contribute to the diversity and adaptability of arid shrub-steppe communities. The fact that the offspring from the isolated female four-wing saltbush plant were sterile and exhibited a different chromosome count of 2n = 45, compared to the salt sage's 2n = 54, suggests a possible case of hybridization that did not result in a viable polyploid species. In angiosperms like sagebrush,

sex and reproduction involve the production of spores in flowers and the subsequent dispersal of pollen, leading to cross-pollination and increased genetic diversity. However, the sterility of the hybrid offspring indicates that successful hybridization is complex and often fraught with challenges, as seen in other plant examples where fertile hybrids emerged only after chromosomal mutations.