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Performance of pathway categories in control conditions and 3 h stress. a: Proportion of the pathway categories at unstressed conditions in DD as compared to IR20. b: Photograph displaying the phenotype of the hydroponically grown 7-day-old seedlings of DD and IR20. The seedlings of DD are considerably taller than IR20.c: Stacked graph of categories in DD and IR20. d: Contributions of accessory categories involved in cell integrity and stress perception. e: Relative expression of common genes in DD and IR20 divided into separate categories. Values indicate the nature of expression in DD as compared to IR20. CM – carbohydrate metabolism, CSGD – cell structure, growth and dynamics, CT/T/W – cellular transport, transporters and water channels, D&D – degradation and detoxification, N/NAM – nucleoproteins/ nucleic acid modifiers, Phot – photosynthesis, P&PI – proteases and protease inhibitors, PFM – protection factors of macromolecules, PK – protein kinases, PP – protein phosphatases, Sig – signaling, TF/RT – transcription factors/regulation of transcription. T/RT – translation/regulation of translation, TP – transmembrane proteins.
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Traditional cultivars of rice in India exhibit tolerance to drought stress due to their inherent genetic variations. Here we present comparative physiological and transcriptome analyses of two contrasting cultivars, drought tolerant Dhagaddeshi (DD) and susceptible IR20. Microarray analysis revealed several differentially expressed genes (DEGs) exc...
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... diffex analysis (p < 0.05, > 2-fold change) of the normalized and log transformed data revealed the number of probe sets expressing differen- tially after 3 h stress is almost double for DD (10,901) w.r.t. its control as compared to the same for IR20 (5,502) ( Supplementary Fig. S3A). The differences in probe set numbers corresponding to differentially expressing genes after 6 h of stress was 8,601 in case of IR20 vis-à-vis 11,041 in DD. ...
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... the list of probe sets obtained after microarray data analysis at the 3 h stress time point in both the cultivars; the number of genes were manually sourced (Methods). The number of genes obtained after manual curation is shown in Supplementary Fig. S3B. While the genes highlighted for each cultivar at 3 h stress were compared with the respective control list to negate those expressed under unstressed conditions, the list of genes common to both the cultivars at 3 h of stress was further modified to obtain a relative fold change (RFC) values by applying the following formula: ...
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... degradation and detoxification (D/D) and protein phosphatases (PP) were considerably down-regulated in DD as compared to IR20; whereas those pertaining to cell division and expansion regulation (CDER), i.e. nucleoproteins/nucleic acid modifiers (N/NAM), photosynthesis (Phot) and translation/regulation of translation (T/RT) were up-regulated in DD (Fig. 3a). It is known that DD is a taller cultivar compared to IR20 and it was evident even at the 7-day-old two-leaf seedling stage (Fig. 3b). The faster vegetative growth seen in DD could be attributed to the rapid changes taking place in the CDER network that houses genes involved in con- trolling plant growth. On exposure to stress, ...
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... those pertaining to cell division and expansion regulation (CDER), i.e. nucleoproteins/nucleic acid modifiers (N/NAM), photosynthesis (Phot) and translation/regulation of translation (T/RT) were up-regulated in DD (Fig. 3a). It is known that DD is a taller cultivar compared to IR20 and it was evident even at the 7-day-old two-leaf seedling stage (Fig. 3b). The faster vegetative growth seen in DD could be attributed to the rapid changes taking place in the CDER network that houses genes involved in con- trolling plant growth. On exposure to stress, however, the expression pattern changed dramatically as compared to the unstressed conditions (Fig. 3c). In DD, among all the genes involved ...
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... even at the 7-day-old two-leaf seedling stage (Fig. 3b). The faster vegetative growth seen in DD could be attributed to the rapid changes taking place in the CDER network that houses genes involved in con- trolling plant growth. On exposure to stress, however, the expression pattern changed dramatically as compared to the unstressed conditions (Fig. 3c). In DD, among all the genes involved in CDER (green boxes in Fig. 3c) the transcript abundance of many were effectively down-regulated as compared to IR20 whereas the proportion of those involved in Dehydration Signaling (DS) (yellow boxes) and Osmotic Signaling (OS) (purple boxes) were up-regulated in DD. The transcript levels of ...
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... vegetative growth seen in DD could be attributed to the rapid changes taking place in the CDER network that houses genes involved in con- trolling plant growth. On exposure to stress, however, the expression pattern changed dramatically as compared to the unstressed conditions (Fig. 3c). In DD, among all the genes involved in CDER (green boxes in Fig. 3c) the transcript abundance of many were effectively down-regulated as compared to IR20 whereas the proportion of those involved in Dehydration Signaling (DS) (yellow boxes) and Osmotic Signaling (OS) (purple boxes) were up-regulated in DD. The transcript levels of genes belonging to T/RT category were significantly down regulated in DD, ...
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... h stress treat- ment indicated that the gamut of genes involved in damage control and repair were rapidly activated in DD such that it would be able to achieve homeostasis faster than IR20. Further, the genes involved in lipid metabolism (essential for maintaining cell membrane stability) were also significantly up-regulated in DD vis-à-vis IR20 (Fig. 3d). This also corroborated with the CMS assay (Fig. ...
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... in the fold change in the expression of genes that are common to both the cultivars. A similar type of analysis carried out with this group of genes would reveal the differences in the kinetics or rate of gene activation/suppression of the genes for a particular category commonly shared by both DD and IR20. The results plotted in a stacked graph (Fig. 3e) showed that the transcripts of genes representing categories, such as cell structure, growth and dynamics (CSGD), N/NAM, Photosynthesis and T/RT, were significantly down-regulated in DD, whereas protection factors of macromole- cules (PFM) was up-regulated. Gene transcripts associated with cell growth and regulation were down-regulated ...
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... whereas those involved in protecting the cellular machinery (deg- radation of unfolded/mis-folded proteins, activation of chaperones, detoxification) were greatly up-regulated in the tolerant cultivar DD. Similar patterns of gene expression as observed in the unstressed conditions (controls) and the common genes obtained after RFC calculation (Fig. 3c,e) could be attributed to the differences in the kinetics of the signaling networks operating in DD vis-à-vis ...
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... microarray analysis revealed that the expression of genes encoding components involved in DS and CDER sub-networks were distinctly altered in the contrasting cultivars during 3 h of drought stress. The components of the DS network were activated earlier in Dhagaddeshi than in IR20 and, likewise, the machinery controlling cell growth and expansion was arrested faster in DD as compared to IR20 in response to the imposed dehydration stress (Figs 3, 4 and 7). At molecular level, DD responded to dehydration by increasing the levels of transcripts encoding for proteins, such as LEA, DREBs, NACs; enzymes for carbohydrate metabolism and ROS scavenging antioxidants (Table 1). ...
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... these networks work closely with each other to alleviate stress and due to the sheer complexities in their functioning they have considerable number of overlapping regulators, making it extremely difficult to dissect the key players unambiguously. Nevertheless, in our data the alteration in the expression of genes encoding components of the detoxification network was fairly identifiable at 3 h stress (Figs 3 and 4). However, as both the cultivars underwent more than 70% loss in their water content after the imposition of 6 h of drought stress (Figs 1 and 2), the expression data obtained at this time point was comparable for both the cultivars, to a large extent. ...
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Citations
... Likewise, transcriptome analysis from other two contrasting maize phenotypes led to a similar result, where drought tolerance might have been achieved through higher expression of genes related to ROS-scavenging, leading to stronger ROS-removal capability (Wang et al. 2022). Similar analyzes have been conducted for other plant species such as rice (Borah et al. 2017) and sugarcane (Contiliani et al. 2022), which also linked increased drought tolerance to stronger antioxidant capacity and to the activation of signalling pathways by ROS-related transcription factors, such as members of the MYB, NAC, and bHLH families. Dou et al. (2015) introduced in potato (Solanum tuberosum cv. ...
Environmental stresses are responsible for limiting soybean yield. To mitigate the impacts generated by water deficit, molecular biology tools are being used to develop genetically modified plants. Previous studies showed that two independent events (B1 and B3) of soybean transgenic plants expressing a Solanum nigrum osmotin (SnOLP) had an increment in drought tolerance. The present study aims to investigate the modulated pathways that results in the drought tolerance promoted by osmotin overexpression in soybean. Transgenic and non-transgenic (NT) plants in the vegetative stage were submitted to water deficit by irrigation suppression for seven days. Control plants were kept irrigated. Physiological variables were monitored and confirmed that the transgenic plants present better performance when compared to the NT plants. The total RNA extracted from leaves was sequenced and data was normalized by DESeq2. A total of 2044 and 1505 differentially expressed genes (DEGs) were identified in B1 and B3 events, respectively. Regarding the B1 event, 769 genes were upregulated and 1275 downregulated. For B3, 541 genes were upregulated and 964 genes were downregulated. Excluding common differentially expressed genes (DEGs) between transgenic and non-transgenic (NT) plants yielded 395 upregulated and 234 downregulated genes, which were shared by B1 and B3 events. The metabolic pathways and gene ontology categories identified are known to be involved in plant responses to drought. Hormonal, photosynthetic, carbohydrate and amino acid metabolism, reactive oxygen species, and post-translational modifications pathways were significantly modulated in transgenic plants. Altogether, the results suggest that osmotin promotes tolerance through an increment in the plant responses elicited by drought.
... RNA-seq analysis and the system biology approach are powerful tools to probe such complex traits. Several transcriptome studies on drought tolerance in rice published in the last decade have further improved our understanding at the systemic level (Lenka et al. 2011;Shankar et al. 2016;Zhang et al. 2016;Borah et al. 2017). Biochemical, physiological, genetic, genomic, and epigenomic approaches are being combined to analyze the complex nature of abiotic stress tolerance in crop plants (Kumar et al. , 2022b. ...
... Biochemical, physiological, genetic, genomic, and epigenomic approaches are being combined to analyze the complex nature of abiotic stress tolerance in crop plants (Kumar et al. , 2022b. A large number of DEGs are obtained in comparative transcriptome studies, many of which are responsible for the necessary morphological and physiological changes (Borah et al. 2017;Kumar et al. 2022c). ...
... Abiotic stresses adversely affect plant growth, development, productivity, and pose threats to global food security. Several reports on transcriptome analysis of rice under drought stress have been published in the last two decades, which contribute a lot to understanding drought tolerance at the systematic level (Hu et al. 2006;Feng et al. 2009;Lenka et al. 2011;Shankar et al. 2016;Zhang et al. 2016;Borah et al. 2017;Kumar et al. 2022c). Effects of drought stress on the performance of plants and stress-responsive genes have been studied mainly at the seedling stage (Feng et al. 2009;Lenka et al. 2011;Shankar et al. 2016;Zhang et al. 2016); however, only a few studies focused on comparative RNA-seq analysis of contrasting rice genotypes under drought stress at the reproductive stage (Ereful et al. 2020). ...
Drought stress has been known to adversely affect growth, development, and productivity of plants to varying extent. Being a multifaceted trait, drought tolerance involves interaction of an array of genes, pathways, and mechanisms. A unique regulatory scheme is adopted by different plants, which provides tolerance to drought stress in association with biochemical and physiological mechanisms. Transcriptome analysis of a drought tolerant [Nagina 22 (N-22)] and drought sensitive (IR-64) cultivars provides insights into the genes/pathways/mechanisms involved in terminal drought stress tolerance. In the present study, comparative physio-biochemical analyses of the rice cultivars under terminal drought stress substantiated their performance. Whole transcriptome analysis of leaf and root from the rice cultivars exposed to terminal drought stress revealed 6077 and 10050 differentially expressed genes (DEGs) in leaf of N-22 and IR-64, respectively, under drought stress. A maximum of 2682 genes were up-regulated exclusively in N-22 while 7198 genes were down-regulated exclusively in leaf of IR-64. Interestingly, the highest number (2594) of genes was down-regulated exclusively in roots of IR-64, while only 1497 gene were up-regulated exclusively in root of N-22. Differential expression of OsNAC10, OsbZIP23, OsABA8ox1, OsCPK4, OsLEA3, and OsNCED4 along with the GO terms enriched with up-regulated genes for transcription factors (TFs), redox homeostasis, and ABA signaling in N-22 under terminal drought stress play crucial roles in stress tolerance. The stress-responsive genes for transcription factors, redox homeostasis, and ABA signaling up-regulated in N-22 were mainly responsible for terminal drought tolerance. These stress-associated genes can be utilized for genetic improvement of rice for drought tolerance.
... For example, late embryogenesis abundant (LEA) proteins [11], ascorbate peroxidase (APX) [12], AP2/ERF family members (OsERF48 and OsERF71) [13,14], bZIP family members (OsbZIP12 and OsbZIP71) [15,16], MYB family members (OsMYB2 and OsMYB6) [17,18] and NAC family members (OsNAC5, OsNAC6 and OsNAC14) [19,20] have been shown to be involved in rice drought tolerance. Various spatio-temporal based transcriptomic studies have identified differentially expressed drought-responsive genes between contrasting rice varieties to drought [21][22][23][24][25]. These studies highlighted the role of a few transcription factors (TFs) that are involved mainly in processes affecting osmoregulation and reactive oxygen species (ROS) scavenging during vegetative drought stress. ...
Background
Reproductive stage drought stress (RDS) is a major global threat to rice production. Due to climate change, water scarcity is becoming an increasingly common phenomenon in major rice-growing areas worldwide. Understanding RDS mechanisms will allow candidate gene identification to generate novel rice genotypes tolerant to RDS.
Results
To generate novel rice genotypes that can sustain yield under RDS, we performed gamma-irradiation mediated mutation breeding in the drought stress susceptible mega rice variety, MTU1010. One of the mutant MM11 (MTU1010 derived mutant11) shows consistently increased performance in yield-related traits under field conditions consecutively for four generations. In addition, compared to MTU1010, the yield of MM11 is sustained in prolonged drought imposed during the reproductive stage under field and in pot culture conditions. A comparative emerged panicle transcriptome analysis of the MTU1010 and MM11 suggested metabolic adjustment, enhanced photosynthetic ability, and hormone interplay in regulating yield under drought responses during emerged panicle development. Regulatory network analysis revealed few putative significant transcription factor (TF)-target interactions involved in integrated signalling between panicle development, yield and drought stress.
Conclusions
A gamma-irradiate rice mutant MM11 was identified by mutation breeding, and it showed higher potential to sustain yield under reproductive stage drought stress in field and pot culture conditions. Further, a comparative panicle transcriptome revealed significant biological processes and molecular regulators involved in emerged panicle development, yield and drought stress integration. The study extends our understanding of the physiological mechanisms and candidate genes involved in sustaining yield under drought stress.
... Similarly, drought-responsive transcription factor encoding genes, i.e. bHLH, NAC, AP2/EREBP, bZIP and MYB have been identified in rice (Sharoni et al., 2011;Baldoni et al., 2015;Shao et al., 2015;Das et al., 2019;Guo et al., 2021). In addition, the accumulation of water-soluble sugars has also been found to be related to drought tolerance in rice (Quan et al., 2010) The transcriptome, proteome and metabolome responses of droughtsensitive and tolerant rice cultivars have been characterized in several studies to gain insights into the drought tolerance mechanism (Liu and Bennett, 2011;Moumeni et al., 2011;Mohammadi et al., 2012;Paul et al., 2015;Zhang et al., 2016;Borah et al., 2017;Xia et al., 2020;Vijayaraghavareddy et al., 2021). The comparative transcriptome analysis revealed the differential expression of genes engaged in hormone biosynthesis, carbohydrate metabolism, secondary metabolites biosynthesis/metabolism, cellular transportation and photosynthesis (Moumeni et al., 2011;Zhang et al., 2016;Borah et al., 2017;Xia et al., 2020). ...
... In addition, the accumulation of water-soluble sugars has also been found to be related to drought tolerance in rice (Quan et al., 2010) The transcriptome, proteome and metabolome responses of droughtsensitive and tolerant rice cultivars have been characterized in several studies to gain insights into the drought tolerance mechanism (Liu and Bennett, 2011;Moumeni et al., 2011;Mohammadi et al., 2012;Paul et al., 2015;Zhang et al., 2016;Borah et al., 2017;Xia et al., 2020;Vijayaraghavareddy et al., 2021). The comparative transcriptome analysis revealed the differential expression of genes engaged in hormone biosynthesis, carbohydrate metabolism, secondary metabolites biosynthesis/metabolism, cellular transportation and photosynthesis (Moumeni et al., 2011;Zhang et al., 2016;Borah et al., 2017;Xia et al., 2020). Similarly, the comparative proteome response of drought-sensitive and tolerant rice cultivars under drought revealed cellular homeostasis, ROS scavenging, NADP(H) homeostasis, chitinase and cell defense tender drought tolerance in rice (Agrawal et al., 2016;Chintakovid et al., 2017;Wang et al., 2017;Anupama et al., 2019). ...
... The drought stress significantly influences the growth and development of seedling. The whole seedlings have been used to investigate the stress responses in maize, sorghum, wheat and rice (Fernandes et al., 2008;Hirsch et al., 2014;Shankar et al., 2016;Borah et al., 2017;Cui et al., 2018;Gupta et al., 2020;Yang et al., 2020). Therefore, we also analyzed the single-sourced whole seedlings of IR64 and N22 cultivars under control and drought stress to reveal their transcriptome, proteome and metabolome responses at the global level and performed integrated multi-omics analysis using statistical methods followed by their functional correlation (Fig. 1). ...
Drought is one of the major consequences of climate change and a serious threat to rice production. Drought stress activates interactions among genes, proteins and metabolites at the molecular level. A comparative multi-omics analysis of drought-tolerant and drought-sensitive rice cultivars can decipher the molecular mechanisms involved in drought tolerance/response. Here, we characterized the global-level transcriptome, proteome, and metabolome profiles, and performed integrated analyses thereof in a drought-sensitive (IR64) and a drought-tolerant (Nagina 22) rice cultivar under control and drought-stress conditions. The transcriptional dynamics and its integration with proteome analysis revealed the role of transporters in regulation of drought stress. The proteome response illustrated the contribution of translational machinery to drought tolerance in N22. The metabolite profiling revealed that aromatic amino acids and soluble sugars contribute majorly to drought tolerance in rice. The integrated transcriptome, proteome and metabolome analysis performed using statistical and knowledge-based methods revealed the preference for auxiliary carbohydrate metabolism through glycolysis and pentose phosphate pathway contributed to drought tolerance in N22. In addition, L-phenylalanine and the genes/proteins responsible for its biosynthesis were also found to contribute to drought tolerance in N22. In conclusion, our study provided mechanistic insights into the drought response/adaptation mechanism and is expected to facilitate engineering of drought tolerance in rice.
... However, in rice, different varieties may have different gene expressions. For instance, the transcriptome analysis revealed a different set of genes were expressed exclusively in the drought-tolerant cultivar (Dhagaddeshi) compared to the drought-susceptible cultivar (IR20) [10]. In Malaysia, breeding work started in the year 2000, which gave rise to many rice varieties, including MR219, MR220, MRQ74, MR232, MR220CL1, MR220CL2, MRM16, MR253 and MR263. ...
MR303 is a newly released Malaysian rice cultivar that comes with special traits as it can be cultivated in less fertile soils. Previous studies stated that miR164b is a key molecule that is responsible for regulating drought stress tolerance in many rice varieties. Thus, this study aims to identify the presence and regulatory role of miR164b in the MR303 variety using both computational and experimental approaches. The stem-loop structure of miR164b (pre-miR164b) was identified through reverse-transcriptase PCR (RT-PCR) with a size of ~ 100 bp. The target prediction by psRNA target revealed that the target gene of miR164b is the NAM protein of the NAC transcription factor. A gene expression study by RT-PCR followed by Image J analysis in both control and drought-treated plants demonstrated low expression of miR164b was observed in the drought sample, which led to the accumulation of its target, NAM1. This study provides preliminary knowledge of the presence of miR164b and its regulatory role in the MR303 rice variety.
... A total of 215 rice genotypes with diverse origins, including potentially aromatic and potentially drought-tolerant genotypes, were screened. Based on information from previous reports, IR 64 was used as a drought susceptible check [37,38] while IR 86781-3-3-1-1 [13] was used as drought tolerant check. These genotypes were provided by the research institutions ISABU and IRRI in accordance with the national and international regulations of plant materials exchange. ...
Drought is among the major abiotic stresses on rice production that can cause yield losses of up to 100% under severe drought conditions. Neither of the rice varieties currently grown in Burundi can withstand very low and irregular precipitation. This study identified genotypes that have putative quantitative trait loci (QTLs) associated with drought tolerance and determined their performance in the field. Two hundred and fifteen genotypes were grown in the field under both drought and irrigated conditions. Genomic deoxyribonucleic acid (DNA) was extracted from rice leaves for further genotypic screening. The results revealed the presence of the QTLs qDTY12.1, qDTY3.1, qDTY2-2_1, and qDTY1.1 in 90%, 85%, 53%, and 22% of the evaluated genotypes, respectively. The results of the phenotypic evaluation showed a significant yield reduction due to drought stress. Yield components and other agronomic traits were also negatively affected by drought. Genotypes having high yield best linear unbiased predictions (BLUPs) with two or more major QTLs for drought tolerance, including IR 108044-B-B-B-3-B-B, IR 92522-45-3-1-4, and BRRI DHAN 55 are of great interest for breeding programs to improve the drought tolerance of lines or varieties with other preferred traits.
... Breeding drought tolerance rice cultivars with high yielding has become a major aim. 53 According to Borah et al. (2017), the majority of the rice cultivars that are tolerant to stress 54 have a low yield, and vice versa. This shortcoming has made the need to understand the host 55 defence mechanism in response to abiotic stresses. ...
... In addition, a comparison of other resistant varieties from GenBank, namely Pokkali, was used. The OsDREB2A Pokkali gene was widely transformed for transgenic plants resistant to osmotic stress (Borah et al. 2017) and as a comparison variety for drought resistance (Zakiyah et al. 2021;Jayaweera et al. 2016). Sequence analysis showed that Lumbung Sewu Cantik also has the same sequence as Pokkali, while the different OsDREB2A sequence was only shown by IR64, which was used as a comparison of sensitive variety and yielded an inferior response under drought stress (Miftahudin et al. 2020). ...
Chrisnawati L, Ernawiati E, Yulianty, Hariri MR. 2022. Polymorphism analysis of drought tolerance gene OsDREB2A in Indonesian local rice from Lampung, Indonesia. Biodiversitas 23: 6352-6357. Drought stress is a significant threat to rice cultivation and the selection of drought-tolerant rice plants is needed to find superior plants. The OsDREB2A gene plays a role in the regulation of drought tolerance and is widely used as a marker. Therefore, this study aims to analyze the OsDREB2A gene polymorphism in the local rice variety of Lampung Lumbung Sewu Cantik, compared to the Inpago 8 drought-tolerant and the IR64 sensitive variety. DNA extraction was performed on fresh leaves using the GENEAID Genomic DNA Mini Kit, amplification by PCR was carried out with the OsDREB2A primer pair, while sequence analysis was conducted with MEGA X and confirmed using the BLAST program. The sequencing results showed that the three rice varieties had the same sequence length of 250 bp. The Lumbung Sewu Cantik variety has the same sequence as Inpago 8, while IR64 has an insertion that causes a frameshift mutation. Furthermore, phylogenetic analysis showed that the Lumbung Sewu Cantik variety was in a similar group with tolerant varieties, while IR64 was in a different group. The similarity of the OsDREB2A Lumbung Sewu Cantik sequence is presumably associated with tolerance to drought.
... In addition, phytohormones have also been found to be integral factors influencing transcriptome profiles for adapting to developmental or stress conditions (Nemhauser et al., 2006;Borah et al., 2017;Ma et al., 2019). Auxin accumulation patterns regulate various aspects of embryonic and postembryonic development. ...
OsMADS29 (M29) is a seed-specific MADS-box transcription factor involved in programmed cell death of nucellar tissue and maintaining auxin:cytokinin homeostasis. It affects embryo and endosperm development and starch filling during seed development in rice. Its expression seems to be tightly regulated by developmental, spatial, and temporal cues; however, cis- and trans-regulatory factors that affect its expression are largely unknown. In silico analysis of the 1.7 kb upstream regulatory region (URR) consisting of 1,290 bp promoter and 425 bp 5′-UTR regions revealed several auxin-responsive and seed-specific cis-regulatory elements distributed across the URR. In this study, the analysis of four URR deletions fused to a downstream β-glucuronidase (GUS) reporter in transgenic rice has revealed the presence of several proximal positive elements and a strong distal negative element (NE). The promoter regions containing auxin-responsive elements responded positively to the exogenous application of auxins to transgenic seedlings. The proximal positive elements are capable of driving reporter expression in both vegetative and reproductive tissues. In contrast, the NE strongly suppresses reporter gene expression in both vegetative and reproductive tissues. In a transient onion peel assay system, the NE could reduce the efficacy of a 2x CaMV 35S promoter by ∼90%. Our results indicate the existence of a complex array of positive and negative regulatory regions along with auxin-responsive elements guiding the development-dependent and spatial expression of M29.
... In accordance with stress tolerance, several investigations have revealed the differences between genotypes or sub-species [21][22][23]. Therefore, the resistant genetic resources from various geography and tolerance mechanisms underpinning drought and salinity stress must be detected. ...
Salinity and drought stress are significant environmental threats, alone or in combination. The current study was conducted to investigate the morpho-physiology, osmotic adjustment, oxidative stress, antioxidant defense and methylglyoxal detoxification of three rice genotypes from the indica (cv. BRRI dhan29 and BRRI dhan48) and japonica (cv. Koshihikari) groups. Eighteen-day-old seedlings of these genotypes were exposed to either in alone salinity (150 mM NaCl) and drought (15% PEG 6000) or in the combination of salinity and drought (150 mM NaCl + 15% PEG 6000) stress in vitro for 72 h. Compared with the control, the water status, biomass and photosynthetic pigments were decreased, where a significant increase was seen in the mortality rate, hydrogen peroxide content, electrolyte leakage, lipoxygenase activity, level of malondialdehyde and methylglyoxal, indicating increased lipid peroxidation in rice genotypes in stress conditions. The non-enzymatic and enzymatic components of the ascorbate-glutathione (AsA-GSH) pool in rice genotypes were disrupted under all stress treatments, resulting imbalance in the redox equilibrium. In contrast, compared to other rice genotypes, BRRI dhan48 revealed a lower Na+/K+ ratio, greater proline (Pro) levels, higher activity of AsA, dehydroascorbate (DHA) and GSH, lower glutathione disulfide (GSSG) and a higher ratio of AsA/DHA and GSH/GSSG, whereas enzymatic components increased monodehydroascorbate reductase, dehydroascorbate reductase, glutathione peroxidase and glyoxalase enzymes. The results showed that a stronger tolerate ability for BRRI dhan48 against stress has been connected to a lower Na+/K+ ratio, an increase in Pro content and an improved performance of the glyoxalase system and antioxidant protection for scavenging of reactive oxygen species. These data can give insight into probable responses to single or combination salinity and drought stress in rice genotypes.
