Molecular Programming of Drought-Challenged Trichoderma harzianum-Bioprimed Rice (Oryza sativa L.)

Abstract

Trichoderma biopriming enhances rice growth in drought-stressed soils by triggering various plant metabolic pathways related to antioxidative defense, secondary metabolites, and hormonal upregulation. In the present study, transcriptomic analysis of rice cultivar IR64 bioprimed with Trichoderma harzianum under drought stress was carried out in comparison with drought-stressed samples using next-generation sequencing techniques. Out of the 2,506 significant (p < 0.05) differentially expressed genes (DEGs), 337 (15%) were exclusively expressed in drought-stressed plants, 382 (15%) were expressed in T. harzianum-treated drought-stressed plants, and 1,787 (70%) were commonly expressed. Furthermore, comparative analysis of upregulated and downregulated genes under stressed conditions showed that 1,053 genes (42%) were upregulated and 733 genes (29%) were downregulated in T. harzianum-treated drought-stressed rice plants. The genes exclusively expressed in T. harzianum-treated drought-stressed plants were mostly photosynthetic and antioxidative such as plastocyanin, small chain of Rubisco, PSI subunit Q, PSII subunit PSBY, osmoproteins, proline-rich protein, aquaporins, stress-enhanced proteins, and chaperonins. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis states that the most enriched pathways were metabolic (38%) followed by pathways involved in the synthesis of secondary metabolites (25%), carbon metabolism (6%), phenyl propanoid (7%), and glutathione metabolism (3%). Some of the genes were selected for validation using real-time PCR which showed consistent expression as RNA-Seq data. Furthermore, to establish host–T. harzianum interaction, transcriptome analysis of Trichoderma was also carried out. The Gene Ontology (GO) analysis of T. harzianum transcriptome suggested that the annotated genes are functionally related to carbohydrate binding module, glycoside hydrolase, GMC oxidoreductase, and trehalase and were mainly upregulated, playing an important role in establishing the mycelia colonization of rice roots and its growth. Overall, it can be concluded that T. harzianum biopriming delays drought stress in rice cultivars by a multitude of molecular programming.

Phytohormone Production Profiles in Trichoderma Species and Their Relationship to Wheat Plant Responses to Water Stress

“…The application of Trichoderma to wheat triggers systemic defense pathways [ 40 ] and seems to be a good choice to minimize damage caused by abiotic stresses [ 35 , 37 ], also limiting environmental pollution. There is sufficient evidence to consider that Trichoderma association can help plants in sustaining drought stress by increasing: (i) the expression of antioxidative enzymes that alleviate the damage caused by the accumulation of ROS and modulating the balance of plant’s phytohormones [ 25 , 41 ]; (ii) the absorption surface that leads the plant to improve water-use efficiency [ 33 ]; and (iii) the synthesis of phytohormones and phytohormonal analogues to promote plant performance.…”

Novel Trichoderma Isolates Alleviate Water Deficit Stress in Susceptible Tomato Genotypes

“…Water deficit stress significantly inhibits crop productivity and quality. Trichoderma inoculation could ameliorate the negative effect of water deficit stress and facilitate growth promotion in plants ( De Palma et al, 2016 ; Bashyal et al, 2021 ). Mastouri et al (2010 , 2012) demonstrated the effects of Trichoderma inoculation on plant performance to be apparent only in stressful environments.…”

“…In addition, NT33 and NT3 increased the chlorophyll content in the drought susceptible genotypes as compared to non-inoculated controls, which is an important pigment essential for absorbing light during photosynthetic process ( Table 3 ). Bashyal et al (2021) reported that genes related to the photosynthesis process, such as those coding for photosystem I subunits, photosystem II core complex proteins, osmotin like proteins, and stomatal development were upregulated in the Trichoderma inoculated plants as compared to non-inoculated controls. Water deficit exposed plants inoculated with Trichoderma exhibit improved physiological health ( Shukla et al, 2012 ; Harman et al, 2019 ; Khoshmanzar et al, 2020 ), similar to our observation in NT33-colonized tomato plants.…”

Effects of Marine Antagonistic Fungi against Plant Pathogens and Rice Growth Promotion Activity

“…44 Trichoderma harzianum-bioprimed rice was reported to enhance rice growth in droughtstressed soils by triggering various respond mechanisms via many pathways. 45 Moreover, many Trichoderma species were reported as a potent producers of IAA and enzymes which enhanced plant tolerance to biotic and abiotic stress. Trichoderma longibrachiatum T6 (TL-6) significantly improved the growth of wheat and enhanced wheat tolerance to NaCl stress by reducing the transcriptional level of ethylene synthesis genes expression, and increasing IAA production gene expression.…”