Exogenous β‐cyclocitral treatment primes tomato plants against drought by inducing tolerance traits, independent of abscisic acid

Abstract

Drought is the most devastating stress for crops. Intensity and duration of drought determine the magnitude of plant damage; similarly, plant ability to counteract drought determines its tolerance capacity. Recent studies revealed that exogenous apocarotenoid treatment confers abiotic stress tolerance to plants. However, much less is known about the role of b-cyclocitral (bCC), the major apocarotenoid, in drought tolerance. Here, we demonstrate bCC's role in improving plants' tolerance against drought stress.• Tomato (Solanum lycopersicum L.) plants were independently treated with water and bCC and grown under either water-limited or irrigated conditions. The bCC-treated drought-exposed (BD) and bCC-treated irrigated (BH) plants were analysed for the major drought tolerance associated traits; water-treated drought-exposed (CD) and water-treated irrigated plants (CH) were used as controls.• On exposure to drought, unlike controls, bCC-treated plants showed no wilting, higher RWC and stomatal conductance, unchanged ABA levels and stomatal closure. The BD plants had increased photosynthesis, chlorophyll content and enhanced root, but not shoot, growth. In addition, bCC treatment enhanced proline accumulation and activity of SOD in both drought-exposed and well irrigated plants.• Taken together, bCC was identified as a potential candidate that improves tomato osmolyte accumulation and superoxide elimination, independent of ABA, and prepares the plant for upcoming drought stress. Our results suggest that bCC can be used to prime crops against drought stress.

β-Cyclocitral, a Master Regulator of Multiple Stress-Responsive Genes in Solanum lycopersicum L. Plants

“…Previously, it was shown that βCC treatment enhances resistance to high light stress and regulates singlet oxygen-responsive genes. Recently, we have seen that in addition to high light, βCC treatment also develops resistance to drought stress and herbivory in tomato and Arabidopsis plants, respectively [3,10,11]. Therefore, we hypothesized that βCC plays a pivotal role in the regulation of multiple stress responses.…”

“…Its productivity and quality are often challenged by various environmental stresses [2]. The extent of damage is dependent on the intensity and duration of the stress to which plants are exposed [3]. However, irrespective of the types of stress and their extent, the generation of reactive oxygen species (ROS) is one of the common hypersensitive responses in stress-exposed plants [4].…”

“…Among these, 1 O 2 is known as the major ROS generated by photooxidative stress and is responsible for the loss of photosystem I and II activity that ultimately induces cell death [6]. However, recent studies have shown that 1 O 2 is also produced after drought and herbivory [3,7,8]. Carotenoids play a prime role in 1 O 2 scavenging.…”

“…In addition, simulated herbivory and jasmonic acid (JA) application also resulted in increased accumulation of βCC [11,12]. Recent studies showed that exogenous application of βCC primes plants against drought and develops resistance against insect herbivores [3,11]. Together, these findings indicate that, presumably, βCC is capable of eliciting multiple stress signals.…”

Regulatory hubs in plant stress adaptation

“…Parvin et al (2021) reported the significance of coumarin-modulated plant defence and glyoxalase systems in alleviating stress-induced oxidative damage. Deshpande et al (2021) reported b-cyclocitral-mediated osmolyte accumulation and burst of superoxide scavenging machinery independent of ABA signalling. Based on the above reports, the mentioned phytoprotectants can be used for priming plant stress tolerance under control conditions; however, field experiments with different crop species in the presence of external chemical supplementation are essential to further verify their availability.…”