Question

Answer the following questions:

A. Name the flower that typically appears first in the Spring and describe and list few environmental factors that lead to its opening.

B Name and describe two defense mechanisms the wild tobacco uses against attackers

Answer 1

B.

1. The moment Manduca sexta, herbivore, begins to feed, a cascade of signaling events leads to increased defense levels; N. attenuata plants recognize herbivory-specific elicitors derived from M. sexta oral secretions (OS), namely, fatty acid-amino acid conjugates (FACs), and quickly activate mitogen-activated protein kinase (MAPK) signaling and, subsequently, JA- and ethylene (ET)-mediated defense responses. These include:

• a highly reconfigured transcriptome that encompasses changes in transcript levels of defense- and growth-related genes
• the release of volatile organic compounds (VOCs) that function as an indirect defense
• the accumulation of herbivore-deterrent or -damaging secondary metabolites, for example, nicotine and trypsin proteinase inhibitors (TPIs). TPIs are a class of important direct defense compounds in Nicotiana (as in many other plants); by inhibiting digestive proteinases in the M. sexta midgut, they slow growth and increase mortality of insect larvae.

2. O-Acyl sugars (O-AS) are abundant trichome-specific metabolites that function as indirect defenses against herbivores of the wild tobacco Nicotiana attenuata; whether they also function as generalized direct defenses against herbivores and pathogens. O-AS consist of branched-chain fatty acids (BCFAs) esterified to the hydroxyl groups of glucose (Glc) or sucrose (Suc). It has been shown that O-AS can deter or repel aphids, beet armyworms, and leaf miners. O-AS also were known to be excellent emulsifiers and surfactants that readily adhere to arthropod cuticles and, thereby, can immobilize or suffocate arthropods. Neonate larvae frequently consume the exudates of glandular trichomes as their first meal, and later-stage larvae consume entire trichomes as they ingest shoot materials. When O-AS enter the high-pH environment of the larval midgut, the BCFAs is de-esterified to give their bodies and frass a distinctive odor that attracts ground-foraging predators, such as the omnivorous ant Pogonomyrmex rugosus.

A. The commonly known earliest/first flower to bloom in spring is Crocus though some minor bulbs also start blooming prior to the crocus. They are slightly photonastic

.  Once a bud is mature, the flower will open on warm sunny days. The growth of epidermal cells of the inner and outer tepal (or petals) surfaces of flowers like the crocus and tulip are differentilly responsive to temperature. When warm, cells on the inside surface grow faster than cells on the outside surface, which causes the tepals to spread outward and thus opens the flower. When cold, like at night, cells on the inner surface slow their growth and cells on the outer surface grow relatively faster causing the flower to close.