Arbuscular Mycorrhizal Symbiosis Improves Ex Vitro Acclimatization of Sugarcane Plantlets (Saccharum spp.) under Drought Stress Conditions

Abstract

The symbiotic associations between arbuscular mycorrhizal fungi (AMF) and plants can induce drought stress tolerance. In this study, we evaluated the effect of Glomus intraradices, a mycorrhizal fungus, on the ex vitro development and survival of sugarcane plantlets subjected to drought stress during the acclimatization stage of micropropagation. In vitro obtained sugarcane plantlets (Saccharum spp. cv Mex 69–290) were inoculated with different doses of G. intraradices (0, 100, and 200 spores per plantlet) during greenhouse acclimatization. Sixty days after inoculation, plantlets were temporarily subjected to drought stress. We evaluated the survival rate, total chlorophyll, total protein, carotenoids, proline, betaine glycine, soluble phenolic content, and antioxidant capacity every 3 days for 12 days. Symbiotic interaction was characterized by microscopy. Our results showed that the survival rate of inoculated plants was higher in 45% than the treatment without mycorrhizae. Total chlorophyll, protein, proline, betaine glycine content, and antioxidant capacity were increased in AMF inoculated plants. The soluble phenolic content was higher in non-inoculated plants than the treatment with mycorrhizae during the drought stress period. Microscopy showed the symbiotic relationship between plant and AMF. The early inoculation of 100 spores of G. intraradices per sugarcane plantlet during the acclimatization stage could represent a preconditioning advantage before transplanting into the field and establishing basic seedbeds.

Arbuscular Mycorrhizal Fungi and Higher Plants

“…Photosynthesis, a key primary metabolic process essential for the synthesis of energy in plant, is drastically affected by drought stress (Ilyas et al 2021). Moderate and severe levels of drought-induced decrease in leaf number and leaf area reduce the concentration of photosynthetic pigments like chlorophylls and carotenoids (Zhang et al 2018a;Mashabela et al 2023), which ultimately hampers photosynthesis in plants (Spinoso-Castillo et al 2023;El-Sawah et al 2023). Up regulated expression of chlorophyll-degrading enzymes and down regulation of chlorophyll biosynthetic enzymes also contribute to a decline in chlorophyll content (Ilyas et al 2021;Saxena et al 2022).…”

“…It was observed that proline content was significantly increased in Eucalyptus camaldulensis, Valeriana officinalis, Citrus aurantium, and Saccharum spp. upon inoculation with Gigaspora albida, Funneliformis mosseae, and a mixture of Glomus hoi, G. mosseae, and G. intraradices, respectively Amanifar and Toghranegar 2020;Hadian-Deljou et al 2020;Spinoso-Castillo et al 2023). The enhanced proline content in plants following AMF inoculation can be due to enhanced activity of enzyme P5CS (Δ′-pyrroline-5-carboxylate synthase), higher expression of proline biosynthetic gene encoding P5CS, enhanced activity of enzyme, glutamate dehydrogenase, and inactivation of enzyme and proline dehydrogenase (Abo-Doma et al 2011).…”

Beneficial Effect of Exogenously Applied Calcium Pyruvate in Alleviating Water Deficit in Sugarcane as Assessed by Chlorophyll a Fluorescence Technique

“…antioxidants that target the excessive accumulation of reactive oxygen species [33]. Possibly, the low carotenoid content contributed to reducing the photosynthetic activity during the period of water deficit and increasing photodegradation, which resulted in a low Fv/Fm ratio.…”

“…In The degradation in the levels of chlorophyll a, chlorophyll b, and carotenoids may be due to the reduced biosynthesis of chlorophyll resulting from photochemical disturbances caused by excess light in the PSII reaction centers [32]. Carotenoids are non-enzymatic antioxidants that target the excessive accumulation of reactive oxygen species [33]. Possibly, the low carotenoid content contributed to reducing the photosynthetic activity during the period of water deficit and increasing photodegradation, which resulted in a low Fv/Fm ratio.…”

Colonization of root endophytic fungus Serendipita indica improves drought tolerance of Pinus taeda seedlings by regulating metabolome and proteome

“…cv. Mex 69-290) increased the levels of proline and glycine betaine under drought stress (Spinoso-Castillo et al, 2023). Therefore, the increased level of stachydrine caused by S. indica inoculation is helpful for P. taeda seedlings under drought stress.…”