Bamboo shoots grow quickly through the rapid elongation of intemodes. In order to veri~ whether DNA methylation affects bamboo shoot elongation, we compared DNA methylation levels at five develop- mental stages of bamboo （Phyllostachys praecox）, including young bamboo shoot of 40-cm at length （S1）, bamboo shoot of 2-cm at length （S2）, young leaf （Y1）, leaf （Y2）, and aging leaf （M）, by using amplified fragment length polymorphism （AFLP） based on KpnI/MseI and Acc65I/MseI platforms. The polymorphism ratio of methylated to un- methylated DNA sites in bamboo shoot （$1 and $2） was higher than that in leaf （Y1, Y2 and M）. The polymorphism ratio of methylated to un- methylated DNA sites in $2 was highest （32%）. Our results suggest that DNA methylation changed greatly at bamboo growing stages, especially in stage of rapid elongation of intemodes.
LU Yong-quanWANG Dong-meiLI Hai-yingJIA QingWU ZeLU Wen-feng
Amplified consensus genetic marker （ACGM） is a PCR-based marker technique that uses primers designed within conserved regions of coding sequences. After a comparison of Cryptomeria japonica and Arabidopsis ESTs to search for conserved sequences, 237 single e-PCR products were obtained. We randomly selected 110 candidate ACGM markers to test. Of the 110 candidate ACGM markers tested, 106 yielded stable and clear PCR products in C. japonica. We then tested the utility of these 106 primer pairs in 10 species, representing 7 genera of Taxodi- aceae. The number of specific amplification primer pairs among those 10 species varied from 49 to 103 （or 46.2±97.2%）. The 106 primer pairs （ACGM loci） were high transferable to Cryptomeria fortunei Hooibrenk （97.2%） but were low in Metasequoia glyptostroboides （46.2%）. The number of PCR bands per primer pair ranged from 1.06 to 1.15, which means that most of the ACGM primers can obtain a single band within these 10 Taxodiaceae species. In summary, our study shows that ACGM is a technique applicable for marker development even in species with limited sequence data.
DNA methylation plays a crucial role in regulating plant development and tissue differentiation. In this study, we compared the methylation levels in leaf, root, and stem in Chamaedorea elegans by using the technique of methylation-sensitive amplified fragment length polymorphism AFLP. Over 19% （42/220） bases were uniformly methy- lated in these tissues. The percentages of polymorphism resulting from varied methylation in mature leaf （L1）, young leaf （L2）, baby leaf （L3）, stem （S）, young root （R1） and lignified root （R2） were 29.5%, 29.0%, 27.1%, 30.7%, 63.0% and 28.3%, respectively. The numbers of poly- morphic loci detected in the leaves of three developmental stages were similar, ranging from 20 to 30. In contrast, roots at the two developmental stages differed greatly, with 145 polymorphic loci detected in R1 and 27 in R2. Our results suggest that the methylation level in leaves slightly increases with aging, while that in roots decreases dramatically with aging.
Myeloblastosis （MYB） is one of the largest transcribed factor families in plants. To gain an overall picture of the evolution of MYB genes in relict plants, we cloned nine novel MYB genes in Taxodiaceae plants （ Taxodium distichum, Taxodium ascendens, Cryptomeria japonica var. Sinensis, Cryptomeria japonica cv. Araucarioides, Cryptomer Ja- ponica, Metasequoia glyptostroboides, Cunninghamia lanceolata, Tai- wania cryptomerioides and Glyptostrobus pensilis）. The deduced amino acid sequences for MYBs showed that the nine MYB proteins contained two DNA binding domains. The first domain is from amino acid position 29 to 78, wherein three tryptophanes at 33, 53 and 73 were separated by 19 amino acids, respectively. The second domain is from amino acid position 82 to 127, wherein three tryptophanes at 86, 105 and 124 were separated by 18 amino acids, respectively, whereas the first tryptophane at amino acid position 86 is replaced by a phenylalanine. The characteri- zation of these conserved domains at nine MYBs indicated that they all belong to the R2R3-MYB group. The secondary structure analysis showed that a-helix and 13-turn are the major motifs of the predicted secondary structure of MYBs. The three dimensional model of each MYB protein showed that the structure is like clip, making it more flexi- ble and mobile. The similarities between the nine MYB proteins in Taxodiaceae were calculated. The highest identical value of 99% is be- tween CjsMYB, CjMYB and CjaMYB, whereas the lowest value of 82% is between TaMYB and C1MYB. According to the phylogenetic tree, the distances between different genera were relatively large whereas those within genera were relatively small. As expected, accessions of the same genus formed a subgroup before being grouped with other genera.
