Elicitation in plant cell and tissue culture: Which of the following are considered abiotic elicitors used to stimulate secondary metabolite production?

Introduction / Context:
Elicitors are signals that enhance secondary metabolite biosynthesis in plant cell, tissue, and organ cultures. They are widely used to boost yields of valuable phytochemicals (alkaloids, phenolics, terpenoids). Elicitors can be biotic (microbe-derived) or abiotic (physical/chemical cues).

Given Data / Assumptions:

• Abiotic elicitors include physical stresses and chemicals that mimic stress.
• Plant cells respond to stress by activating defense-related pathways.
• Typical readouts include increased accumulation of target metabolites.

Concept / Approach:
UV irradiation induces oxidative stress and signaling cascades; osmotic shock perturbs water potential and triggers stress pathways; heavy metal ions provoke reactive oxygen species and defense responses. All are classic abiotic elicitors used experimentally and industrially to enhance metabolite production in vitro.

Step-by-Step Solution:
Recognize UV, osmotic, and metal ion stresses as abiotic stimuli.Connect these stresses to activation of defense gene networks (e.g., PAL, CHS) and metabolite accumulation.Select the inclusive option “All of these.”

Verification / Alternative check:
Case studies show higher flavonoid or alkaloid titers after applying abiotic elicitors, confirming their practical efficacy in culture systems.

Why Other Options Are Wrong:

• Individual choices are correct but incomplete.
• Only live microbial suspensions: these are biotic elicitors, not abiotic.

Common Pitfalls:
Overstressing cultures leading to growth arrest; not optimizing dose and timing for elicitor application.

Final Answer:
All of these.