Strigolactones Biosynthesis and Their Role in Abiotic Stress Resilience in Plants: A Critical Review

In this review we present basic overview of SL biosynthesis and perception with a detailed discussion on our present understanding of SLs and their critical role to tolerate environmental constraints

Wajeeha Saeed; Saadia Naseem; Zahid Ali


Scholarcy highlights

  • Strigolactones were initially known as host-derived germination stimulants for parasitic weeds from the genera Striga and Orobanche
  • SLs were found to be host-detection and hyphal-branching signals for arbuscular mycorrhizal fungi. In addition to their original, dual role as signaling molecules in the rhizosphere, SL were further demonstrated to be a new class of branch-inhibiting phytohormones, which regulate the overall architecture of land plants
  • The SL-abscisic acid cross-talk has been increasingly spotlighted by research aimed at dissecting and understanding abiotic stress tolerance; interest is escalating because of the theoretical possibility of engineering phytohormonal signaling and metabolism for the improvement of crop performances under natural stress conditions
  • If we really are to do so, and exploit SL biology to the purpose of sustainable agriculture, the most immediate challenge ahead is to understand the molecular underpinnings of the pervasive SL effects on plant phenotypes under stress, as well as how they may connect physiological strain to appropriate development progression
  • How do SLs modulate ABA sensitivity? Is their effect linked to altered efficiency or abundance of components in the ABA signaling machinery, and/or to a modulation of ABA transport? Data in Arabidopsis, Lotus and tomato indicate that in the former, ABA transporters are down-regulated in SL-depleted vs. wild-type leaves under drought; while in the latter two, SL-defective leaves retain the ability to close their stomata comparably to the wild-type in response to exogenous ABA fed through the petiole, if given sufficient time
  • No significant differences in ABA levels could be detected between wild-type and SL mutants in this species, but stressed tissues were not analyzed; this and the previous datasets on tomato and Lotus collectively suggest a general positive influence of SLs on ABA levels under stress, possibly with some species-specific variability
  • Both observations support some contribution to the final phenotype of SL-depleted plants, for less efficient ABA translocation
  • Is the effect on sensitivity mutual, i.e., is abscisic acid able to affect sensitivity to SLs, and/or their translocation? Is there a connection between SLs and regulatory molecules such as miRNAs, as proven for other hormones and if so, is this connection relevant for SL effects under drought? based on the newly acquired knowledge, can we envisage breeding or management strategies that can move agriculture one step closer to sustainability, for example by exploiting the drought-tolerant phenotype of heterografted tomato plants? As reported by Visentin et al

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