Unraveling the mechanisms of drought tolerance enhancement in Sorghum bicolor through Glomus mosseae inoculation: Insights from comparative analysis of Super 2 and Konawe Selatan accessions

The increasing frequency of droughts due to climate change has negatively impacted crop yield. This research aimed to study the mechanism of Glomus mosseae in improving the drought tolerance of Sorghum bicolor plants, specifically in Super 2 (S2) and Konawe Selatan (KS) accession. G. mosseae was used to inoculate the plants grown in the sterile zeolite. The drought was imposed in two cycles by suspending irrigation for six days per cycle. After nine weeks, the plants were harvested and subjected to various analyses. The results showed that drought stress lowered biomass, pigment concentrations by 45% and 23%, and leaf relative water content (RWC) by 34% and 17% for S2 and KS accessions, respectively. Conversely, malondialdehyde (MDA) levels rose by 20% and 9%, while proline synthesis was improved by 7% and 16% on S2 and KS, respectively, compared to the control. In contrast, inoculation with G. mosseae markedly augmented chlorophyll levels by 85% and 25%, elevated leaf relative water content by 33% and 8%, and enhanced P content by 20% and 19% for S2 and KS accessions, respectively, when compared to drought-exposed treatments. Additionally, G. mosseae inoculation preserved root length, biomass, leaf number, proline synthesis, and nitrogen content, while inducing a reduction in MDA levels by 11% and 6% in S2 and KS, respectively, in relation to the drought treatments. G. mosseae improves sorghum's drought tolerance by reducing water loss through improving water and nutrient uptake via external hyphae and enhancing photosynthetic properties via pigment protection. Furthermore, it was shown that G. mosseae is highly efficient at maintaining proline balance and enhancing the effectiveness of both enzymatic and non-enzymatic antioxidants to eliminate reactive oxygen species (ROS). KS accession exhibited elevated levels of nitrogen content, leaf number, upper ground biomass, chlorophyll and RWC. Conversely, the Super 2 accession manifested higher levels of lower ground biomass, root length, root colonization and phosphorus content. The addition of G. mosseae to the soil shows great potential as a sustainable agricultural approach under climate change conditions, specifically for the promotion of sorghum plant survival under drought stress. This potential stems from the ability of G. mosseae to enhance key plant properties, including photosynthetic performance and water balance regulation, through the expansion of extraradical hyphal growth. Moreover, G. mosseae supplementation maintains proline levels, enhances nutrient uptake and detoxifies reactive oxygen species by promoting antioxidant capacity. As a result of these properties, sorghum plants exhibit increased biomass and resistance to drought stress, providing an important tool for future sustainable agriculture under climate change. (c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.