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Taxonomy and pathogenicity of Erwinia cacticida sp. nov.

A total of 108 pectolytic, soft-rotting Erwinia strains were collected from 11 types of cacti growing in Arizona, Texas, northern Mexico, and Australia between 1958 and 1989. Four strains were collected from soils beneath or close to naturally rotting saguaro cacti. Collectively, these strains caused soft rots of saguaro, organ pipe, and senita cacti, Opuntia (cactus) fruits and pads, tomato fruits, and potato slices, but only occasionally caused soft rots of slices of carrot roots. A numerical cluster analysis showed that 98 of the 112 strains formed a uniform group (cluster 1A) that was distinguished from other pectolytic erwinias by an API 20E code of 1205131, by negative reactions in API 50CHE tests for L-arabinose, myo-inositol, D-cellobiose, melibiose, and D-raffinose, and, in supplemental tests, by positive reactions for malonate and growth at 43 degrees C. The average levels of DNA relatedness of 22 cluster 1A strains to the proposed type strain (strain 1-12) as determined by the hydroxyapatite method were 88% in 60 degrees C reactions (with 1% divergence within related sequences) and 87% in 75 degrees C reactions. The levels of relatedness to the type strains of other Erwinia spp. were less than or equal to 38% in 75 degrees C reactions. Cluster 1A strains also had a characteristic cellular fatty acid profile containing cyclo-(11,12)-nonadecanoic acid (C19:0 Cyclo C11-12) and missing tridecanoic acid (C13:0), heptadecanoic acid (C17:0), and cis-9-heptadecenoic acid (C17:1 CIS 9), which separated them from other pectolytic erwinias. Collectively, these data indicate that the members of cluster 1A are members of a new species, which we name Erwinia cacticida. Three cactus strains in cluster 1B appear to represent a second new species that is closely related to E. cacticida; these strains are designated E. cacticida-like pending the availability of additional strains for testing. The remaining cactus strains (in cluster 4) have the physiological, DNA, and fatty acid profiles of Erwinia carotovora.

DNA, Bacterial

Macromerine and normacromerine biosynthesis in Coryphantha macromeris var. runyonii.

The biosynthetic conversion of epinephrine to normacromerine in Coryphantha macromeris (Engelm.) Br. and R. var. runyonii (Br. and R.) L. Benson (Cactacae) has been studied. Metanephrine, which has been isolated from this cactus and is a normal metabolite of epinephrine in mammalian systems, appeared to be the likely intermediate between epinephrine and normacromerine. Normacromerine turnover studies suggested a 16-day interval between metanephrine administration and harvest of the cacti. During this incubation period, the cacti specifically converted 4.77% of the administered DL-7-3H-metanephrine to normacromerine. Based on biochemical precedents, the postulated metabolic fate of normacromerine in the cactus was an enzymatic N-methylation to give macromerine. However, radiolabeled normacromerine was a very ineffecient precursor to macromerine.

Alkaloids

Extension of longevity in Drosophila mojavensis by environmental ethanol: differences between subraces.

Drosophila mojavensis adults, which breed and feed on necrotic cacti, show an increase in longevity when exposed to atmospheric ethanol. The increase in longevity is accompanied by retention of mature ovarioles and is independent of diet. Differences in longevity among strains from different localities were detected for females. Strains from Arizona and Sonora, Mexico, showed the greatest increase in longevity, while strains from Baja California, Mexico, showed the least increase. These differences may be controlled by the alcohol dehydrogenase locus, the octanol dehydrogenase locus, and modifier genes, because the aduld response is correlated with the frequency of alcohol dehydrogenase alleles, as well as second chromosomal inversions containing the octanol dehydrogenase locus. The longevity response is also consistent with the more uneven distribution and availability of the host plant in Arizona and Sonora, Mexico. Strains from Arizona and Sonora, Mexico, have a high frequency of Adh-S, the allele whose product is heat and pH tolerant. The host plant, organpipe cactus, exhibits extremes in temperature and pH in the same geographic region. Strains from Baja California, Mexico, possess a high frequency of Adh-F, whose product is heat and pH sensitive. The substrate in this region, agria cactus, has moderate temperature and pH extremes and contains relatively high concentrations of isopropanol. Isopropanol is presumable a selective agen favorable to Adh-F. The environmental heterogeneity that is proposed for maintaining the alleles at the alcohol dehydrogenase locus is the interaction of substrate alcohol content with temperature and pH. Substrates that do not contain appreciable amounts of isopropanol and are exposed to high temperatures and exhibit variable pH favor Adh-S, while substrates containing isopropanol and having moderate temperatures and pH favor Adh-F.

Alcohol Oxidoreductases

Alkaloids of Carnegiea gigantea. Arizonine, a new tetrahydroisoquinoline alkaloid.

The alkaloid composition of the giant cactus, Carnegiea gigantea Br. & R., was studied. Chromatographic separation led to the isolation of four tetrahydroisoquinoline alkaloids: carnegine, salsolidine, gigantine and arizonine. The structure of the new natural product, arizonine, was establihsed by spectroscopic data and total synthesis via two independent routes. Salsolidine is reported for the first time in the cacti. Also new to this species are 3-methoxytyramine and 3,4-dimethoxypenethylamine, which were identified in the alkaloid extract by gas chromatography-mass spectrometry. Dopamine was isolated from fresh plant material.

Alkaloids

Taxogenomic analysis of Pichia senei sp. nov. and new insights into hybridization events in the Pichia cactophila species complex.

Three strains of a novel yeast species were isolated from necrotic cactus tissues of Cereus saddianus and Micranthocereus dolichospermaticus and from phytotelmata of Bromelia karatas. DNA sequence analysis of the Internal Transcribed Spacer (ITS) region and D1/D2 domains of the large subunit ribosomal RNA, along with whole genome phylogenomic analysis, showed that this yeast is most closely related to Pichia insulana, Pichia cactophila, and Pichia inconspicua. The new species differs by 10-13 nucleotide substitutions from these species in D1/D2 sequences and exhibits <90% genome-wide average nucleotide identity to them. The name Pichia senei sp. nov. is proposed for the novel species, which is homothallic and produces asci with one to four hat-shaped ascospores. The holotype is CBS 16311 (MycoBank MB 858723). Taxogenomic analyses of the P. cactophila species complex, including P. senei, provide new insights about the hybridizations events that shaped this group. Pichia insulana and P. inconspicua are identified as the parental lineages that originated P. cactophila, and P. senei also appears closely related to one of the progenitors of P. inconspicua. We assess phylogeny, heterozygosity, and ploidy to explore the processes shaping diversity, showing how genomic data support yeast species delimitation and reveal complex hybridization.

Phylogeny