Negative Roles of Strigolactone-Related SMXL6, 7 and 8 Proteins in Drought Resistance in Arabidopsis

Abstract

Previous investigations have shown that the SUPPRESSORS OF MAX2 1-LIKE6, 7 and 8 (SMXL6, 7 and 8) proteins redundantly repress strigolactone (SL) signaling in plant growth and development. Recently, a growing body of evidence indicated that SLs positively regulate plant drought resistance through functional analyses of genes involved in SL biosynthesis and positive regulation of SL signaling. However, the functions of the SL-signaling negative regulators SMXL6, 7 and 8 in drought resistance and the associated mechanisms remain elusive. To reveal the functions of these SMXL proteins, we analyzed the drought-resistant phenotype of the triple smxl6,7,8 mutant plants and studied several drought resistance-related traits. Our results showed that the smxl6,7,8 mutant plants were more resistant to drought than wild-type plants. Physiological investigations indicated that the smxl6,7,8 mutant plants exhibited higher leaf surface temperature, reduced cuticle permeability, as well as decreases in drought-induced water loss and cell membrane damage in comparison with wild-type plants. Additionally, smxl6,7,8 mutant plants displayed an increase in anthocyanin biosynthesis during drought, enhanced detoxification capacity and increased sensitivity to abscisic acid in cotyledon opening and growth inhibition assays. A good correlation between the expression levels of some relevant genes and the examined physiological and biochemical traits was observed. Our findings together indicate that the SMXL6, 7 and 8 act as negative regulators of drought resistance, and that disruption of these SMXL genes in crops may provide a novel way to improve their drought resistance.

Transcriptome Analysis Reveals Potential Roles of Abscisic Acid and Polyphenols in Adaptation of Onobrychis viciifolia to Extreme Environmental Conditions in the Qinghai-Tibetan Plateau

“…Generally, when facing with detrimental environmental stresses, plants initiate a wide range of enzymatic and non-enzymatic antioxidants to scavenge excess free radicals, including ROS [ 54 , 78 , 79 ]. The polyphenolic compounds are the central components of non-enzymatic antioxidants [ 54 ]; and thus, promotion of their biosynthesis is a defense strategy against adverse environmental conditions [ 76 , 80 , 81 ]. Consistent with the results of transcriptome analysis, results of RT-qPCR analysis also verified up-regulation of several key flavonoid, phenylpropanoid, and anthocyanin biosyntheses-related genes, especially OvFLS , in the TD/MH comparison ( Figure 11 A,B).…”

Triflumizole as a Novel Lead Compound for Strigolactone Biosynthesis Inhibitor

“…In this study, it was found that triflumizole inhibits SL biosynthesis in rice by inhibiting Os900 activity. As SLs play an important role in plant development and resistance of environmental stress [ 1 , 39 ], triflumizole may be useful tool for analyzing the influence of SL biosynthesis inhibition and controlling the damage of root parasitic plants. However, because the dwarf phenotype is a side effect of triflumizole, a structure-activity relationship study using triflumizole as the lead compound will be necessary in the near future to attempt to reduce this side effect and conclusively establish triflumizole derivatives as a specific SL biosynthesis inhibitor.…”

Genotype‐ and tissue‐specific physiological and biochemical changes of two chickpea (Cicer arietinum) varieties following a rapid dehydration

“…In the present study, the activities of SOD, GPOX, PPO, APX and CAT enzymes increased in roots and leaves of both chickpea varieties exposed to RD treatments (Figure 5A-J). However, despite the increased activities of these antioxidant enzymes upon RD (Figure 5A-J Secondary metabolites, including TPhs and flavonoids, are known to be important antioxidant compounds for scavenging ROS in stressed plants (Gao et al 2020;Li et al, 2020;Ma et al 2014;Okunlola et al 2017;Patel et al 2020;Rahman et al 2021). In the present study, we detected a large increase in the contents of TPhs and flavonoids in the roots and leaves of both chickpea varieties in response to RD-induced over-production of ROS (Figure 4C-J).…”