First report on DNA content of three species of Amorphophallus.

The Amorphophallus genus is a perennial herb which belongs to the family Araceae. There are more than 170 species in this genus, which is widely distributed in tropical and subtropical areas. As a kind of food and medicine Amorphophallus has been used for more than 2000 years in China. Because of the high content of konjac glucomannan (KGM) and dietary fiber, it has attracted more attention worldwide. In this article, the DNA contents of A. konjac, A. albus and A. bulbifer in China, A. albus, A. paeoniifolius and A. muelleri in Indonesia were estimated by using flow cytometry. In the samples of China, the DNA contents were 12.95 ± 0.73 pg/2C in A. konjac, 10.51 ± 0.05 pg/2C in A. albus and 17.61 pg/2C in A. bulbifer, and for Indonesia, 14.16 ± 0.48 pg/2C in A. albus (flowering), 8.49 ± 0.2 pg/2C in A. paeoniifolius and 17.84 ± 1.46 pg/2C in A. muelleri were used. Interspecific variation was found significantly (P<0.01), suggesting that DNA content might be a parameter that can be used to differentiate the species. Intraspecific variation has also been found significantly (P<0.01), whether in the same region or between two regions. As far as we know, this is the first report ongenome size estimation of the A. konjac, A. albus and A. muelleri using flow cytometry. Understanding the genome size of Amorphophallus species will help to sequence the genome and analyse the genetic diversity, evolutionary relationship and geographical variation pattern of Amorphophallus species.

Comparative analysis of complete chloroplast genome sequences of four major Amorphophallus species.

Amorphophallus (Araceae) contains more than 170 species that are mainly distributed in Asia and Africa. Because the bulbs of Amorphophallus are rich in glucomannan, they have been widely used in food, medicine, the chemical industry and so on. To better understand the evolutionary relationships and mutation patterns in the chloroplast genome of Amorphophallus, the complete chloroplast genomes of four species were sequenced. The chloroplast genome sequences of A. albus, A. bulbifer, A. konjac and A. muelleri ranged from 162,853 bp to 167,424 bp. The A. albus chloroplast (cp) genome contains 113 genes, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The A. bulbifer cp genome contains 111 genes, including 78 protein-coding genes, 29 tRNA genes and 4 rRNA genes. A. muelleri contains 111 and 113 genes, comprising 78 and 80 protein-coding genes, respectively, 29 tRNA genes and 4 rRNA genes. The IR (inverted repeat) region/LSC (long single copy) region and IR/SSC (short single copy) region borders of the four Amorphophallus cp genomes were compared. In addition to some genes being deleted, variations in the copy numbers and intron numbers existed in some genes in the four cp genomes. One hundred thirty-four to 164 SSRs (simple sequence repeats) were detected in the four cp genomes. In addition, the highest mononucleotide SSRs were composed of A and T repeat units, and the majority of dinucleotides were composed of AT and TA. SNPs (single nucleotide polymorphisms) and indels (insertion-deletions) were calculated from coding genes and noncoding genes, respectively. These divergences comprising SSRs, SNPs and indel markers will be useful in testing the maternal inheritance of the chloroplast genome, identifying species differentiation and even in breeding programs. Furthermore, the regression of ndhK was detected from four Amorphophallus cp genomes in our study. Complete cp genome sequences of four Amorphophallus species and other plants were used to perform phylogenetic analyses. The results showed that Amorphophallus was clustered in Araceae, and Amorphophallus was divided into two clades; A. albus and A. konjac were clustered in one clade, and A. bulbifer and A. muelleri were clustered in another clade. Phylogenetic analysis among the Amorphophallus genus was conducted based on matK and rbcL. The phylogenetic trees showed that the relationships among the Amorphophallus species were consistent with their geographical locations. The complete chloroplast genome sequence information for the four Amorphophallus species will be helpful for elucidating Amorphophallus phylogenetic relationships.

Genetic variation in wild populations of the tuber crop Amorphophallus konjac (Araceae) in central China as revealed by AFLP markers.

Amorphophallus konjac is an economically important crop. In order to provide baseline information for sustainable development and conservation of the wild plant resources of A. konjac, we studied the genetic diversity and population structure of this species using amplified fragment length polymorphism (AFLP) molecular markers. We sampled 139 individuals from 10 wild populations of A. konjac in central China. Using five AFLP primer combinations, we scored a total of 270 DNA fragments, most of which were polymorphic (98.2%). Percentage of polymorphic loci, Nei's genetic diversity index, and Shannon's information index showed high levels of genetic variation within A. konjac populations. Analysis of molecular variance indicated that most of the variance (68%) resided within populations. The coefficient of genetic differentiation between populations was 0.348 and the estimated gene flow was 0.469, indicating that there was limited gene flow among the populations. Unweighted pair group method with arithmetic mean cluster analysis and principal coordinates analysis indicated that geographically close populations were more likely to cluster together. The Mantel test revealed a significant correlation between geographic and genetic distances (R2 = 0.2521, P < 0.05). The special insect-pollination system of A. konjac and the complex geography of central China are likely to have contributed to the current pattern of genetic variation of this species. In the present study, we provide several suggestions on the future protection of the wild plant genetic resources of A. konjac.

Potential phylogenetic utility of the nuclear FLORICAULA/LEAFY second intron: comparison with three chloroplast DNA regions in Amorphophallus (Araceae).

FLORICAULA/LEAFY (FLO/LFY) is a single-copy nuclear-encoded homeotic gene containing two introns. We have investigated the utility of the second intron of FLO/LFY (FLint2) as a tool for phylogeny reconstruction at lower taxonomic levels. As an example, the phylogeny of 46 Amorphophallus, two Pseudodracontium, and four outgroup species is reconstructed using maximum parsimony and maximum likelihood analyses of FLint2 sequences. We designed new primers based on conserved sequences of the second and third exon for use in a range of Aroid taxa to amplify and sequence the second intron. In Amorphophallus FLint2 proved to be rather short (143-222 bp), highly variable and unsaturated. In all but two species a single amplification product was found. Results from phylogenetic analysis of FLint2 are largely congruent with results using the chloroplast regions rbcL, matK, and trnL, and compare favorably in percentage of informative characters, overall homoplasy levels, number of well-supported clades in consensus trees and resolution of ingroup relationships within Amorphophallus. When amplification products are not too large, alignment is relatively straightforward, and sequences are used in combination with other fast evolving markers, the FLint2 intron may be a valuable new tool for phylogenetic studies at lower taxonomic levels.

[Chromosome and karyotype analysis of Amorphophallus coaetaneus].

The research of Amorphophallus coaetaneus chromosome shows that the chromosome number of normal diploid is 2n = 26, karyotype formula is 2n = 26 = 20m + 6sm, which belongs to "2B" type. Compared with other species in the same genus, Amorphophallus coaetaneus is more primitive.