Environmental stresses profoundly altered accumulation of nonsense mRNAs including intron-retaining （IR） transcripts in Arabidopsis. Temporal patterns of stress-induced IR mRNAs were dissected using both oscillating...Environmental stresses profoundly altered accumulation of nonsense mRNAs including intron-retaining （IR） transcripts in Arabidopsis. Temporal patterns of stress-induced IR mRNAs were dissected using both oscillating and non-oscillating transcripts. Broad-range thermal cycles triggered a sharp increase in the long IR CCA1 isoforms and altered their phasing to different times of day. Both abiotic and biotic stresses such as drought or Pseudomonas syringae infection induced a similar increase. Thermal stress induced a time delay in accumulation of CCA1 14Rb transcripts, whereas functional mRNA showed steady oscillations. Our data favor a hypothesis that stress-induced instabilities of the central oscillator can be in part compensated through fluctuations in abundance and out-of-phase oscillations of CCA1 IR transcripts. Taken together, our results support a concept that mRNA abundance can be modulated through altering ratios between functional and nonsense/IR transcripts. SR45 protein specifically bound to the retained CCA1 intron in vitro, suggesting that this sp!icing factor could be involved in regulation of intron retention. Transcriptomes of nonsense-mediated mRNA decay （NMD）-impaired and heat-stressed plants shared a set of retained introns associated with stress- and defense-inducible transcripts. Constitutive activation of certain stress response networks in an NMD mutant could be linked to disequilibrium between functional and nonsense mRNAs.展开更多
With the exception of rice, little is known about the existence of respiratory burst oxidase homolog （rboh） gene in cereals. The present study reports the cloning and analysis of a novel rboh gene, termed ZmrbohB, f...With the exception of rice, little is known about the existence of respiratory burst oxidase homolog （rboh） gene in cereals. The present study reports the cloning and analysis of a novel rboh gene, termed ZmrbohB, from maize （Zea mays L.）. The full-length cDNA of ZmrbohB encodes a 942 amino acid protein containing all of the respiratory burst oxidase homolog catalytically critical motifs. Alternative splicing of ZmrbohB has generated two transcript isoforms, ZmrbohB-α and -β. Spliced transcript ZmrbohB-β retains an unspliced intron 11 that carries a premature termination codon and probably leads to nonsense-mediated mRNA decay. Expression analysis showed that two splice isoforms were differentially expressed in various tissues and at different developmental stages, and the major product was ZmrbohB-e. The transcripts of ZmrbohB-α accumulated markedly when the maize seedlings were subjected to various abiotic stimuli, such as wounding, cold （4℃）, heat （40℃）, UV and salinity stress. In addition, several abiotic stimuli also affected the alternative splicing pattern of ZmrbohB except wounding. These results provide new insight into roles in the expression regulation of plant rboh genes and suggest that ZrnrbohB gene may play a role in response to environmental stresses.展开更多
Ser/Arg-rich （SR） genes encode proteins that play pivotal roles in both constitutive and alternative splicing of pre-mRNA. However, not much effort has been made to investigate the alternative splicing of their own ...Ser/Arg-rich （SR） genes encode proteins that play pivotal roles in both constitutive and alternative splicing of pre-mRNA. However, not much effort has been made to investigate the alternative splicing of their own pre-mRNA. In this study, we conducted comprehensive analyses of pre-mRNA splicing for 22 SR genes in three rice （Oryza sativa L.） ecotypes indica, japonica andjavanica. Using different ecotypes we characterized the variations in expression and splicing patterns of rice SR genes in different tissues and at different developmental stages. In addition, we compared the divergence in expression and splicing patterns of SR genes from seedlings of different rice ecotypes in response to hormones application and environmental stresses. Our results revealed the complexity of alternative splicing of SR genes in rice. The splicing varies in different tissues, in different ecotypes, in response to stresses and hormones. Thus, our study suggested that SR genes were subjected to sophisticated alternative splicing although their encoding proteins were involved in the splicing process.展开更多
Cultivars of maize （Zea mays L.） with different sensitivity to drought were exposed to 0.3 mol/L sorbitol （-1.4 MPa water potential） for 24 h. Exposure to water deficiency significantly reduced the growth of both ...Cultivars of maize （Zea mays L.） with different sensitivity to drought were exposed to 0.3 mol/L sorbitol （-1.4 MPa water potential） for 24 h. Exposure to water deficiency significantly reduced the growth of both shoots （coleoptile and hypocotyl） and roots. Shoot growth was inhibited more than the growth of roots. Osmotic stress enhanced accumulation of soluble sugars. Electrolyte leakage, a cell injury index, was slightly increased after 0.3 mol/L sorbitoh Respiration was measured in the presence and absence of 2,6-dlchloro-phenol indophenoh 2,6-Dichloro-phenol indophenol did not influence respiration rates, because statistically equal results were observed under both conditions. Total respiration （VT） decreased after osmoticum treatment. There were no significant differences in the VT among the cultlvars analysed. The decrease In VT was caused by a decline In the activities and capacities of both cytochrome （Vcyt, Vcyt） and alternative pathway （Valt, Valt） of respiration. A high residual respiration （Vres） was observed, up to 27% of total uninhibited respiration. The result of uncoupler use clearly indicated that coupling was maintained after 24 h of osmotic stress. The recovery of the respiration rate was comparable with that of non-stressed control rates. According to these observations, no possible mltochondrial damage is expected. Water deficiency did not induce a stimulation of the alternative oxidase, so we assume that the stimulation of the alternative pathway is not related to drought stress resistance; rather, the function of the alternative pathway is to balance carbon metabolism and electron transport in a response to a changing environment.展开更多
To better understand the response of rice to nutrient stress, we have taken a systematic approach to identify rice genes that respond to deficiency of macronutrients and affect rice growth. We report here the expressi...To better understand the response of rice to nutrient stress, we have taken a systematic approach to identify rice genes that respond to deficiency of macronutrients and affect rice growth. We report here the expression and bio- logical functions of a previously uncharacterized rice gene that we have named NRR （nutrition response and root growth）. NRR is alternatively spliced, producing two 5＇-coterminal transcripts, NRRa and NRRb, encoding two proteins of 308 and 223 aa, respectively. Compared to NRRb, NRRa possesses an additional CCT domain at the C-terminus. Expression of NRR in rice seedling roots was significantly influenced by deficiency of macronutrients. Knock-down of expression of NRRa or NRRb by RNA interference resulted in enhanced rice root growth. By contrast, overexpression of NRRa in rice exhibited significantly retarded root growth. These results revealed that both NRRa and NRRb played negative regulatory roles in rice root growth. Our findings suggest that NRRa and NRRb, acting as the key components, modulate the rice root archi- tecture with the availability of macronutrients.展开更多
Osmotic dehydration of wheat seedlings in -0.5 MPa polyethylene glycol ( PEG) solutions for 24, 48 and 72 h resulted in mild, moderate and severe water stress respectively in leaves, but only caused mild water stress ...Osmotic dehydration of wheat seedlings in -0.5 MPa polyethylene glycol ( PEG) solutions for 24, 48 and 72 h resulted in mild, moderate and severe water stress respectively in leaves, but only caused mild water stress in roots as reflected by the changes in relative water content (RWC) . In response to the above water stress conditions, leaf total respiratory rate (Vt,) decreased progressively, and the alternative pathway (AP) capacity ( Valt) and its actual operation activity (ρValt) decreased more severely. Water stress also led to continuous reduction in cytochrome pathway (CP) activity ( ( ρ Vcyt) and different changes in the contribution of ρValt and p' Vcyt to Vt in leaves, with ρValt/ Vt, decreasing and ρ' Vcyt,/ Vt, increasing. The change pattern of root Vt was similar to that of its RWC, while root Valt and ρValt were found to decrease during the first 24 h of stress and thereafter recover to a level close to that of the control (Oh). These data indicate that the alternative pathway is sensitive to water stress and can adapt mild water stress. The results of northern hybridization using an alternative oxidase gene ( Aox) as probe revealed that there was a good correlation between Valt (also ρValt) and Aox mRNA levels in both leaves and roots, suggesting that water stress affects the development and operation of AP respiration through affecting the expression of the alternative oxidase gene.展开更多
文摘Environmental stresses profoundly altered accumulation of nonsense mRNAs including intron-retaining （IR） transcripts in Arabidopsis. Temporal patterns of stress-induced IR mRNAs were dissected using both oscillating and non-oscillating transcripts. Broad-range thermal cycles triggered a sharp increase in the long IR CCA1 isoforms and altered their phasing to different times of day. Both abiotic and biotic stresses such as drought or Pseudomonas syringae infection induced a similar increase. Thermal stress induced a time delay in accumulation of CCA1 14Rb transcripts, whereas functional mRNA showed steady oscillations. Our data favor a hypothesis that stress-induced instabilities of the central oscillator can be in part compensated through fluctuations in abundance and out-of-phase oscillations of CCA1 IR transcripts. Taken together, our results support a concept that mRNA abundance can be modulated through altering ratios between functional and nonsense/IR transcripts. SR45 protein specifically bound to the retained CCA1 intron in vitro, suggesting that this sp!icing factor could be involved in regulation of intron retention. Transcriptomes of nonsense-mediated mRNA decay （NMD）-impaired and heat-stressed plants shared a set of retained introns associated with stress- and defense-inducible transcripts. Constitutive activation of certain stress response networks in an NMD mutant could be linked to disequilibrium between functional and nonsense mRNAs.
基金Supported by the State Key Basic Research and Development Plan of China (2003CB114302)the National Natural Science Foundation of China (30571122).
文摘With the exception of rice, little is known about the existence of respiratory burst oxidase homolog （rboh） gene in cereals. The present study reports the cloning and analysis of a novel rboh gene, termed ZmrbohB, from maize （Zea mays L.）. The full-length cDNA of ZmrbohB encodes a 942 amino acid protein containing all of the respiratory burst oxidase homolog catalytically critical motifs. Alternative splicing of ZmrbohB has generated two transcript isoforms, ZmrbohB-α and -β. Spliced transcript ZmrbohB-β retains an unspliced intron 11 that carries a premature termination codon and probably leads to nonsense-mediated mRNA decay. Expression analysis showed that two splice isoforms were differentially expressed in various tissues and at different developmental stages, and the major product was ZmrbohB-e. The transcripts of ZmrbohB-α accumulated markedly when the maize seedlings were subjected to various abiotic stimuli, such as wounding, cold （4℃）, heat （40℃）, UV and salinity stress. In addition, several abiotic stimuli also affected the alternative splicing pattern of ZmrbohB except wounding. These results provide new insight into roles in the expression regulation of plant rboh genes and suggest that ZrnrbohB gene may play a role in response to environmental stresses.
基金supported by the National Basic Research Program of China (2011CB100401)the National Science Fund of China for Distinguished Young Scientists(30825030)+1 种基金the National Natural Science Foundation of China (30970260,30770466 and 30971752)the Key Project from Chongqing Local Government,China(2010AA1019)
文摘Ser/Arg-rich （SR） genes encode proteins that play pivotal roles in both constitutive and alternative splicing of pre-mRNA. However, not much effort has been made to investigate the alternative splicing of their own pre-mRNA. In this study, we conducted comprehensive analyses of pre-mRNA splicing for 22 SR genes in three rice （Oryza sativa L.） ecotypes indica, japonica andjavanica. Using different ecotypes we characterized the variations in expression and splicing patterns of rice SR genes in different tissues and at different developmental stages. In addition, we compared the divergence in expression and splicing patterns of SR genes from seedlings of different rice ecotypes in response to hormones application and environmental stresses. Our results revealed the complexity of alternative splicing of SR genes in rice. The splicing varies in different tissues, in different ecotypes, in response to stresses and hormones. Thus, our study suggested that SR genes were subjected to sophisticated alternative splicing although their encoding proteins were involved in the splicing process.
基金Supported by Slovak Grant Agency for Science VEGA （2/4036/04）. Publication of this paper is supported by the National Natural Science Foundation of China （30424813） and Science Publication Foundation of the Chinese Academy of Sciences,
文摘Cultivars of maize （Zea mays L.） with different sensitivity to drought were exposed to 0.3 mol/L sorbitol （-1.4 MPa water potential） for 24 h. Exposure to water deficiency significantly reduced the growth of both shoots （coleoptile and hypocotyl） and roots. Shoot growth was inhibited more than the growth of roots. Osmotic stress enhanced accumulation of soluble sugars. Electrolyte leakage, a cell injury index, was slightly increased after 0.3 mol/L sorbitoh Respiration was measured in the presence and absence of 2,6-dlchloro-phenol indophenoh 2,6-Dichloro-phenol indophenol did not influence respiration rates, because statistically equal results were observed under both conditions. Total respiration （VT） decreased after osmoticum treatment. There were no significant differences in the VT among the cultlvars analysed. The decrease In VT was caused by a decline In the activities and capacities of both cytochrome （Vcyt, Vcyt） and alternative pathway （Valt, Valt） of respiration. A high residual respiration （Vres） was observed, up to 27% of total uninhibited respiration. The result of uncoupler use clearly indicated that coupling was maintained after 24 h of osmotic stress. The recovery of the respiration rate was comparable with that of non-stressed control rates. According to these observations, no possible mltochondrial damage is expected. Water deficiency did not induce a stimulation of the alternative oxidase, so we assume that the stimulation of the alternative pathway is not related to drought stress resistance; rather, the function of the alternative pathway is to balance carbon metabolism and electron transport in a response to a changing environment.
文摘To better understand the response of rice to nutrient stress, we have taken a systematic approach to identify rice genes that respond to deficiency of macronutrients and affect rice growth. We report here the expression and bio- logical functions of a previously uncharacterized rice gene that we have named NRR （nutrition response and root growth）. NRR is alternatively spliced, producing two 5＇-coterminal transcripts, NRRa and NRRb, encoding two proteins of 308 and 223 aa, respectively. Compared to NRRb, NRRa possesses an additional CCT domain at the C-terminus. Expression of NRR in rice seedling roots was significantly influenced by deficiency of macronutrients. Knock-down of expression of NRRa or NRRb by RNA interference resulted in enhanced rice root growth. By contrast, overexpression of NRRa in rice exhibited significantly retarded root growth. These results revealed that both NRRa and NRRb played negative regulatory roles in rice root growth. Our findings suggest that NRRa and NRRb, acting as the key components, modulate the rice root archi- tecture with the availability of macronutrients.
基金Project supported by the National Natural Science Foundation of China (Grant No.39670070).
文摘Osmotic dehydration of wheat seedlings in -0.5 MPa polyethylene glycol ( PEG) solutions for 24, 48 and 72 h resulted in mild, moderate and severe water stress respectively in leaves, but only caused mild water stress in roots as reflected by the changes in relative water content (RWC) . In response to the above water stress conditions, leaf total respiratory rate (Vt,) decreased progressively, and the alternative pathway (AP) capacity ( Valt) and its actual operation activity (ρValt) decreased more severely. Water stress also led to continuous reduction in cytochrome pathway (CP) activity ( ( ρ Vcyt) and different changes in the contribution of ρValt and p' Vcyt to Vt in leaves, with ρValt/ Vt, decreasing and ρ' Vcyt,/ Vt, increasing. The change pattern of root Vt was similar to that of its RWC, while root Valt and ρValt were found to decrease during the first 24 h of stress and thereafter recover to a level close to that of the control (Oh). These data indicate that the alternative pathway is sensitive to water stress and can adapt mild water stress. The results of northern hybridization using an alternative oxidase gene ( Aox) as probe revealed that there was a good correlation between Valt (also ρValt) and Aox mRNA levels in both leaves and roots, suggesting that water stress affects the development and operation of AP respiration through affecting the expression of the alternative oxidase gene.
