Objective:To understand the evolutionary relationship of NCED3 in Glycyrrhiza L.and find genetic evidence of its local adaptation.Meanwhile,lay the foundation for relieving the demand and subsequent starvation of Glyc...Objective:To understand the evolutionary relationship of NCED3 in Glycyrrhiza L.and find genetic evidence of its local adaptation.Meanwhile,lay the foundation for relieving the demand and subsequent starvation of Glycyrrhiza resources.Methods:NCED3 were isolated from six species of Glycyrrhiza L.by rapid amplification of cDNA ends and a homology cloning strategy.The basic properties and evolutionary relationships of NCED3 were analyzed by bioinformatics.Results:Six NCED3 genes formed two clusters;they were under purifying selection and were highly conserved in evolution (Ka/Ks≤).There was very little functional divergence among the NCED3s (Alpha value 0.071).The contents of ABA in the six species were divided into two groups.Conclusion:This study provides the first analysis of the evolution of NCED3s in six species of Glycyrrhiza.Six NCED3 genes were slow evolutionary rates in six NCED3s.Different genetic relationships to Glycyrrhiza adapted to various environments.The changes in ABA content were consistent with the evolution of NCED3.Whether there are direct relationships between NCED3 and environmental adaptation,the answer is uncertain,and we hope to show more positive results in the further study of NCED3 in Glycyrrhiza L.展开更多
ABA, acting as a stress signal, plays crucial roles in plant resistance to water stress. Because ABA signal production is based on ABA biosynthesis, the regulation of NCED, a key enzyme in the ABA biosynthesis pathway...ABA, acting as a stress signal, plays crucial roles in plant resistance to water stress. Because ABA signal production is based on ABA biosynthesis, the regulation of NCED, a key enzyme in the ABA biosynthesis pathway, is normally thought of as the sole factor controlling ABA signal production. Here we demonstrate that ABA catabolism in combination with a synergistic regulation of ABA biosynthesis plays a crucial role in governing ABA signal production. Water stress induced a significant accumulation of ABA, which exhibited different patterns in detached and attached leaves. ABA catabolism followed a temporal trend of exponential decay for both basic and stress ABA, and there was little difference in the catabolic half-lives of basic ABA and stress ABA. Thus, the absolute rate of ABA catabolism, i.e. the amount of ABA catabolized per unit time, increases with increased ABA accumulation. From the dynamic processes of ABA biosynthesis and catabolism, it can be inferred that stress ABA accumulation may be governed by a synergistic regulation of all the steps in the ABA biosynthesis pathway. Moreover, to maintain an elevated level of stress ABA sustained activation of NCED3 should be required. This inference was supported by further findings that the genes encoding major enzymes in the ABA biosynthesis pathway, e.g. NCED3, AAO3 and ABA3 were all activated by water stress, and with ABA accumulation progressing, the expressions of NCED3, AAO3 and ABA3 remained activated. Data on ABA catabolism and gene expression jointly indicate that ABA signal production is controlled by a sustained activation of NCED3 and the synergistic regulation of ABA biosynthesis and catabolism.展开更多
Drought tolerance is a comprehensive quantitative trait that is being understood further at the molecular genetic level. Abscisic acid （ABA） is the main drought-induced hormone that regulates the expression of many ...Drought tolerance is a comprehensive quantitative trait that is being understood further at the molecular genetic level. Abscisic acid （ABA） is the main drought-induced hormone that regulates the expression of many genes related to drought responses. 9-cis-epoxycarotenoid dioxygenase （NCED3） is thought to be a key enzyme in ABA biosynthesis. In this paper, we measured the ABA content increase under drought stress, and sequenced and compared the sequence of AtNCED3 among 22 Arabidopsis thaliana accessions. The results showed that the fold of ABA content increase under drought stress was highly variable among these accessions. High density single nucleotide polymorphism （SNP） and insertion/deletion （indel） were found in the AtNCED3 region, on average one SNP per 87.4 bp and one indel per 502 bp. Nucleotide diversity was significantly lower in the coding region than that in non-coding regions. The results of an association study with ANOVA analysis suggested that the 274th site （P←→S） and the 327th site （P←→R） amino acid variations might be the cause of ABA content increase of 163av accession under drought stress.展开更多
基金the National Natural Science Foundation of China(81373909).
文摘Objective:To understand the evolutionary relationship of NCED3 in Glycyrrhiza L.and find genetic evidence of its local adaptation.Meanwhile,lay the foundation for relieving the demand and subsequent starvation of Glycyrrhiza resources.Methods:NCED3 were isolated from six species of Glycyrrhiza L.by rapid amplification of cDNA ends and a homology cloning strategy.The basic properties and evolutionary relationships of NCED3 were analyzed by bioinformatics.Results:Six NCED3 genes formed two clusters;they were under purifying selection and were highly conserved in evolution (Ka/Ks≤).There was very little functional divergence among the NCED3s (Alpha value 0.071).The contents of ABA in the six species were divided into two groups.Conclusion:This study provides the first analysis of the evolution of NCED3s in six species of Glycyrrhiza.Six NCED3 genes were slow evolutionary rates in six NCED3s.Different genetic relationships to Glycyrrhiza adapted to various environments.The changes in ABA content were consistent with the evolution of NCED3.Whether there are direct relationships between NCED3 and environmental adaptation,the answer is uncertain,and we hope to show more positive results in the further study of NCED3 in Glycyrrhiza L.
基金Supported by the National Basic Research Program of China (Grant No. 2003CB114300)the National Natural Science Foundation of China (Grant No. 30470160)
文摘ABA, acting as a stress signal, plays crucial roles in plant resistance to water stress. Because ABA signal production is based on ABA biosynthesis, the regulation of NCED, a key enzyme in the ABA biosynthesis pathway, is normally thought of as the sole factor controlling ABA signal production. Here we demonstrate that ABA catabolism in combination with a synergistic regulation of ABA biosynthesis plays a crucial role in governing ABA signal production. Water stress induced a significant accumulation of ABA, which exhibited different patterns in detached and attached leaves. ABA catabolism followed a temporal trend of exponential decay for both basic and stress ABA, and there was little difference in the catabolic half-lives of basic ABA and stress ABA. Thus, the absolute rate of ABA catabolism, i.e. the amount of ABA catabolized per unit time, increases with increased ABA accumulation. From the dynamic processes of ABA biosynthesis and catabolism, it can be inferred that stress ABA accumulation may be governed by a synergistic regulation of all the steps in the ABA biosynthesis pathway. Moreover, to maintain an elevated level of stress ABA sustained activation of NCED3 should be required. This inference was supported by further findings that the genes encoding major enzymes in the ABA biosynthesis pathway, e.g. NCED3, AAO3 and ABA3 were all activated by water stress, and with ABA accumulation progressing, the expressions of NCED3, AAO3 and ABA3 remained activated. Data on ABA catabolism and gene expression jointly indicate that ABA signal production is controlled by a sustained activation of NCED3 and the synergistic regulation of ABA biosynthesis and catabolism.
基金Supported by State Key Basic Research and Development Plan of China(2003CB114302)
文摘Drought tolerance is a comprehensive quantitative trait that is being understood further at the molecular genetic level. Abscisic acid （ABA） is the main drought-induced hormone that regulates the expression of many genes related to drought responses. 9-cis-epoxycarotenoid dioxygenase （NCED3） is thought to be a key enzyme in ABA biosynthesis. In this paper, we measured the ABA content increase under drought stress, and sequenced and compared the sequence of AtNCED3 among 22 Arabidopsis thaliana accessions. The results showed that the fold of ABA content increase under drought stress was highly variable among these accessions. High density single nucleotide polymorphism （SNP） and insertion/deletion （indel） were found in the AtNCED3 region, on average one SNP per 87.4 bp and one indel per 502 bp. Nucleotide diversity was significantly lower in the coding region than that in non-coding regions. The results of an association study with ANOVA analysis suggested that the 274th site （P←→S） and the 327th site （P←→R） amino acid variations might be the cause of ABA content increase of 163av accession under drought stress.
