Hsp90 and reactive oxygen species regulate thermotolerance of rice seedlings via induction of heat shock factor A2 (OsHSFA2) and galactinol synthase 1 (OsGolS1)

Abstract

<p style="text-align:justify;"> <span style="font-size:10.0pt;font-family:""><span style="font-family:Verdana;">Heat stress induces expression of a set of thermotolerance-related genes in plants. We focused on rice (</span><i><span style="font-family:Verdana;">Oryza sativa</span></i><span style="font-family:Verdana;"> L.) homologs of the gene family that encodes galactinol synthase (OsGolS), which is closely related to the </span><i><span style="font-family:Verdana;">Arabidopsis thaliana</span></i><span style="font-family:Verdana;"> galactinol synthase (AtGolS</span><i><span style="font-family:Verdana;">) </span></i><span style="font-family:Verdana;">family whose expression is</span><i> </i><span style="font-family:Verdana;">induced under various stresses. OsGolS1 was highly up-regulated compare to the level of OsGolS2 in re- sponse to heat stress. Interestingly, OsGolS1</span><i> </i><span style="font-family:Verdana;">was also up-regulated by treatment with the Hsp90 inhibitor, geldanamycin (GDA). Expression profiles of OsGolS1 were correlated to those of OsHsfA2</span><i> </i><span style="font-family:Verdana;">under the GDA treatments. Treatment with GDA increased expression of OsHsfA2, but marginally increased or did not change OsHsfA1</span><i> </i><span style="font-family:Verdana;">expression</span><i><span style="font-family:Verdana;">. </span></i><span style="font-family:Verdana;">Notably, gel shift assay indicated that OsHsfA2 binds directly to OsGolS1 promoter region and that OsHsfA1 also binds to the promoter regions of OsHsfA2. Both OsHsfA2</span><i> </i><span style="font-family:Verdana;">and OsGolS1 were dramatically induced in response to heat stress. Accordingly, galactinol and raffinose contents in rice seedlings increased significantly following the induction of</span><i> </i><span style="font-family:Verdana;">OsGolS1. Pre-treatment of rice seedlings with raffinose or GDA improved their thermotolerance. These results suggest that OsGolS1 plays an important role in response to heat stress, possibly via the transcription cascade of OsHsfA1-OsHsfA2 that leads to galactinol and raffinose accumulation, and that the increased content of these carbohydrates is a </span></span> </p> <span style="font-size:10pt;font-family:Verdana;">key response factor for rice seedlings to enhance thermotolerance.</span

Spermidine Induces Expression of Stress Associated Proteins (SAPs) Genes and Protects Rice Seed from Heat Stress-Induced Damage during Grain-Filling

“…Zhang [49] further identified that HSP90 (CHLOROPLAST HEAT SHOCK PROTEIN 90) was the substrate protein of TaSAP5, and its degradation was mediated by 26S proteasome. Treatment of rice seedlings with GDA (geldamycin, HSP90 inhibitor) significantly increased the expression of the endogenous heat shock transcription factor OsHsfA2 and the heat tolerance of the seedlings [50]. The role of HSFs in heat-tolerance and other abiotic stresses had been well confirmed [51], among which HsfA1s was the main regulator of the heat stress response [52].…”

Heat stress effects on livestock: molecular, cellular and metabolic aspects, a review

“…Among the cited HSP classes, HSP70 and HSP 90 were correlated with the development of thermotolerance (Hue et al., ). In farm animals, heat stress was shown to increase both HSP‐70 and HSP‐90 in sheep (Romero et al., ; Salces‐Ortiz et al., ), buffalo (Kapila et al., ; Kishore et al., ), cattle (Deb et al., ; Kishore et al., ), broilers (Yu et al., ) and goats (Dangi et al., ).…”

Transcription profiles reveal sugar and hormone signaling pathways mediating tree branch architecture in apple (Malus domestica Borkh.) grafted on different rootstocks

“…The expression levels of galactinol synthase 1-like (GolS1-like) were higher in the leaves of dwarfing trees than in VR trees (S4 Table and Fig 9). Galactinol synthase (GolS) controls the rate-limiting step of raffinose-family oligosaccharide (RFO) biosynthesis by synthesizing galactinol from myo-inositol and UDP-galactose, and the accumulation of galactinol and RFOs can protect the photosynthetic apparatus when plants are under oxidative stress [43,44]. It may be speculated that GolS1-like contributes to stress resistance of dwarfing rootstock apples.…”