The NAC-like transcription factor CsNAC7 positively regulates the caffeine biosynthesis-related gene yhNMT1 in Camellia sinensis

Caffeine is an important functional substance and is abundant in tea plant, but little is known about how its biosynthesis is regulated by transcription factors. In this study, the NAC-like transcription factor-encoding gene CsNAC7, which is involved in caffeine synthesis, was isolated from a Yinghong 9 cDNA library using a yeast one-hybrid assay; this gene comprises 1371 bp nucleotides and is predicted to encode 456 amino acids. The expression of CsNAC7 at the transcriptional level in tea shoots shared a similar pattern with that of the caffeine synthase gene yhNMT1 in the spring and summer, and its expressed protein was localized in the nucleus. Assays of gene activity showed that CsNAC7 has self-activation activity in yeast, that the active region is at the N-terminus, and that the transient expression of CsNAC7 could significantly promote the expression of yhNMT1 in tobacco leaves. In addition, overexpression or silencing of CsNAC7 significantly increased or decreased the expression of yhNMT1 and the accumulation of caffeine in transgenic tea calli, respectively. Our data suggest that the isolated transcription factor CsNAC7 positively regulates the caffeine synthase gene yhNMT1 and promotes caffeine accumulation in tea plant.

De novo assembly, annotation and molecular marker identification from the leaf transcriptome of Ocimum gratissimum L

Ocimum gratissimum L. is a well-known medicinal plant with several therapeutic properties, but molecular studies on this species are lacking. Therefore, we have sequenced the whole transcriptome from the leaves of O. gratissimum and assembled 121,651 transcripts. The transcriptome of O. gratissimum was closely related to Sesamum indicum and Erythranthe guttata in congruence with the molecular phylogenetic relationships among these species. Further, 62,194 transcripts were annotated and classified according to the GO terms concerning the biological process, cellular component and metabolic function. In the KEGG pathway analysis, 34,876 transcripts were mapped to 149 pathways and 1410 of them were involved in the biosynthesis of secondary metabolites. In the phenylpropanoid pathway, 101 transcripts were associated with the biosynthesis of eugenol, the principal constituent of the essential oil of O. gratissimum. In the caffeine metabolism pathway, none of the transcripts was related to caffeine biosynthesis, supportive of the caffeine-free nature of Ocimum. Transcripts coding for the metallothionein were abundant in the leaves, supporting the observation that O. gratissimum is an accumulator of heavy metals. We also identified the 930 transcripts coding for 59 transcription factors families with myeloblastosis transcription factors being the most predominant. About 6500 simple sequence repeats were identified, which will be useful in DNA marker-based applications. This is the first report of the leaf transcriptome of O. gratissimum, which will serve as an essential resource for further molecular studies in this important medicinal species.

Characterization of genome-wide genetic variations between two varieties of tea plant (Camellia sinensis) and development of InDel markers for genetic research

Background: Single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) are the major genetic variations and are distributed extensively across the whole plant genome. However, few studies of these variations have been conducted in the long-lived perennial tea plant. Results: In this study, we investigated the genome-wide genetic variations between Camellia sinensis var. sinensis ‘Shuchazao’ and Camellia sinensis var. assamica ‘Yunkang 10’, identified 7,511,731 SNPs and 255,218 InDels based on their whole genome sequences, and we subsequently analyzed their distinct types and distribution patterns. A total of 48 InDel markers that yielded polymorphic and unambiguous fragments were developed when screening six tea cultivars. These markers were further deployed on forty-six tea cultivars for transferability and genetic diversity analysis, exhibiting information with an average 4.02 of the number of alleles (Na) and 0.457 of polymorphism information content (PIC). The dendrogram showed that the phylogenetic relationships among these tea cultivars are highly consistent with their genetic backgrounds or original places. Interestingly, we observed that the catechin/caffeine contents between ‘Shuchazao’ and ‘Yunkang 10’ were significantly different, and a large number of SNPs/InDels were identified within catechin/caffeine biosynthesis-related genes. Conclusion: The identified genome-wide genetic variations and newly-developed InDel markers will provide a valuable resource for tea plant genetic and genomic studies, especially the SNPs/InDels within catechin/caffeine biosynthesis-related genes, which may serve as pivotal candidates for elucidating the molecular mechanism governing catechin/caffeine biosynthesis.

Characterization of genome-wide genetic variations between two varieties of tea plant (Camellia sinensis) and development of InDel markers for genetic research

Background Single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) are the major genetic variations and are distributed extensively across the whole plant genome. However, few studies of these variations have been conducted in the long-lived perennial tea plant. Results In this study, we investigated the genome-wide genetic variations between Camellia sinensis var. sinensis ‘Shuchazao’ and Camellia sinensis var. assamica ‘Yunkang 10’, identified 7,511,731 SNPs and 255,218 InDels based on their whole genome sequences, and we subsequently analyzed their distinct types and distribution patterns. A total of 48 InDel markers that yielded polymorphic and unambiguous fragments were developed when screening six tea cultivars. These markers were further deployed on 46 tea cultivars for transferability and genetic diversity analysis, exhibiting information with an average 4.02 of the number of alleles (Na) and 0.457 of polymorphism information content (PIC). The dendrogram showed that the phylogenetic relationships among these tea cultivars are highly consistent with their genetic backgrounds or original places. Interestingly, we observed that the catechin/caffeine contents between ‘Shuchazao’ and ‘Yunkang 10’ were significantly different, and a large number of SNPs/InDels were identified within catechin/caffeine biosynthesis-related genes. Conclusion The identified genome-wide genetic variations and newly-developed InDel markers will provide a valuable resource for tea plant genetic and genomic studies, especially the SNPs/InDels within catechin/caffeine biosynthesis-related genes, which may serve as pivotal candidates for elucidating the molecular mechanism governing catechin/caffeine biosynthesis.

Characterization of genome-wide genetic variations between two varieties of tea plant (Camellia sinensis) and development of InDel markers for genetic research

Single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) are the major genetic variations and are distributed extensively across the whole plant genome. However, few studies of these variations have been conducted in the long-lived perennial tea plant. In this study, we investigated the genome-wide genetic variation between Camellia sinensis var. sinensis ‘Shuchazao’ and Camellia sinensis var. assamica ‘Yunkang 10’, identified 7,511,731 SNPs and 255,218 InDels based on their whole genome sequences, and we subsequently analyzed their distinct types and distribution patterns. A total of 48 InDel markers that yielded polymorphic and unambiguous fragments were developed when screening six tea cultivars. These markers were further deployed on forty-six tea cultivars for transferability and genetic diversity analysis, exhibiting information with an average 4.02 of the number of alleles (Na) and 0.457 of polymorphism information content (PIC). The dendrogram showed that the phylogenetic relationships among these tea cultivars are highly consistent with their genetic backgrounds or original places. Interestingly, we observed that the catechin/caffeine contents between ‘Shuchazao’ and ‘Yunkang 10’ were significantly different, and a large number of SNPs/InDels were identified within catechin/caffeine biosynthesis-related genes. The identified genome-wide genetic variation and newly-developed InDel markers will provide a valuable resource for tea plant genetic and genomic studies, especially the SNPs/InDels within catechin/caffeine biosynthesis-related genes, which may serve as pivotal candidates for elucidating the molecular mechanism governing catechin/caffeine biosynthesis.

Characterization of genome-wide genetic variation between two varieties of tea plant (Camellia sinensis) and development of InDel markers for genetics research

Single nucleotide polymorphisms (SNPs) and Insertions/Deletions (InDels) are the major genetic variations and distributed extensively across the plant whole genome. Few investigations of these variations, however, have been performed in the long-lived perennial tea plant. Here, we have investigated the genome-wide genetic variation between Camellia sinensis var. sinensis ‘Shuchazao’ and Camellia sinensis var. assamica ‘Yunkang 10’, generating 7,511,731 SNPs and 255,218 InDels based on their whole genome sequences, and subsequently analyzed their distinct types and distribution patterns. A total of 48 InDel markers that yielded polymorphic and unambiguous fragments were developed when screening six tea cultivars. These markers were further deployed on forty-six tea cultivars for transferability and genetic diversity analysis, exhibiting informative with an average 4.02 of the number of alleles ( Na ) and 0.457 of polymorphism information content (PIC). The dendrogram showed that the phylogenetic relationships among these tea cultivars are highly consistent with their genetic backgrounds or original places. Interestingly, we observed that the content of catechin/caffeine between ‘Shuchazao’ and ‘Yunkang 10’ were significantly different, and a large number of SNPs/InDels were identified within catechin/caffeine biosynthesis-related genes. The identified genome-wide genetic variation and newly-developed InDel markers will provide a valuable resource for tea plant genetics and genomics studies, especially those SNPs/InDels within catechin/caffeine biosynthesis-related genes can be served as pivotal candidates for elucidating the molecular mechanism of catechin/caffeine biosynthesis.