Effect of strigolactone on growth, photosynthetic efficiency, antioxidant activity, and osmolytes accumulation in different maize (<i>Zea mays</i> L.) hybrids grown under drought stress

Drought alters plant physiology, morphology, and biochemical pathways, necessitating effective mitigation strategies. Strigolactones (SLs) are phytohormones known to enhance plant growth under abiotic stress. However, their specific impact on drought stress in maize remains unclear. This study aimed to determine the optimal SL concentration for mitigating drought stress in two maize hybrids (HY-1898, FH-1046). Maize plants were subjected to 60% field capacity drought stress in a pot experiment. After 40 d, different concentrations (0, 0.001, 0.01, and 0.1 mg L−1) of the synthetic SL analogue GR24 were applied to evaluate their effects on growth features, photosynthesis attributes, and osmolyte accumulation in the maize hybrids. Results showed that exogenous SL application significantly increased photosynthetic pigments in maize hybrids under drought stress. Chlorophyll content, gas exchange characteristics, net CO2 assimilation rate, stomatal conductance, water use efficiency, and antioxidant activities were enhanced by GR24. Leaf ascorbic acid and total phenolics also increased with SL application. Organic osmolytes, such as glycine betaine and free proline, were elevated in both maize hybrids under drought stress. Yield-related parameters, including cob diameter, cob weight, number of seeds per cob, and number of seeds per plant, were significantly increased by GR24 under drought stress. Our findings highlight the potential of GR24 foliar application to mitigate drought stress and promote maize growth and grain yield in a concentration-dependent manner. The minimum effective SL concentration against drought stress was determined to be 0.01 mg L−1. Overall, foliar application of GR24 could serve as a sustainable approach for drought tolerance in agriculture.</p

Table_1_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.XLSX

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p

Table_7_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.docx

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p

Table_2_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.XLSX

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p

Table_4_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.XLSX

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p

Table_6_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.XLSX

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p

Table_3_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.XLSX

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p

Table_5_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.XLSX

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p

Data_Sheet_1_Characterization of B-box family genes and their expression profiles under abiotic stresses in the Melilotus albus.ZIP

B-box (BBX) proteins are one of the zinc-finger transcription factor that plays a critical role in plant development, growth, and multiple stress responses. Although BBX genes have been reported in many model organisms, no comprehensive study has yet been conducted on the BBX genes in Melilotus albus, and the biological functions of this family remain unknown. In this study, a total of 20 BBX (MaBBX) genes were identified in M. albus and were phylogenetically divided into five clades. BBX members within the same clade showed similar conserved domain, suggesting similarity of potential biological function. Analysis of MaBBX conserved motifs showed that every subfamily contained two common motifs. Distribution mapping shows that BBX proteins are nonrandomly localized in eight chromosomes. The synteny showed that most homologous gene pairs of the MaBBX gene family were amplified by segmental replication, which meant segmental replication was the main way for the MaBBX gene family to evolve. Additionally, the cis-element analysis predicted light-responsive, various hormone and stress-related elements in the promoter regions of MaBBXs. Furthermore, the expression levels of all 20 MaBBX genes were detected by qRT-PCR under salt, cold, and dark stresses in M. albus. Moreover, it was observed that 16 genes had higher expression levels after 3 h of salt treatment, 10 genes were significantly upregulated after 3 h of cold treatment, and all genes were up regulated after 3 h of dark treatment, and then appeared to decline. In addition, it was also noticed that MaBBX13 may be an important candidate for improving tolerance to abiotic stress. The prediction of protein tertiary structure showed that the tertiary structures of members of the same subfamily of MaBBX proteins were highly similar. The hypothesis exhibited that most of the MaBBX proteins were predicted to be localized to the nucleus and cytoplasm and was validated by transient expression assays of MaBBX15 in tobacco leaf epidermal cells. This study provides useful information for further investigating and researching the regulatory mechanisms of BBX family genes in response to abiotic stresses in M. albus.</p