Diverse novel mesorhizobia nodulate New Zealand native Sophora species

Forty eight rhizobial isolates from New Zealand (NZ) native Sophora spp. growing in natural ecosystems were characterised. Thirty eight isolates across five groups showed greatest similarity to Mesorhizobium ciceri LMG 14989T with respect to their 16S rRNA and concatenated recA, glnll and rpoB sequences. Seven isolates had a 16S rRNA sequence identical to M. amorphae ATCC 19665T but showed greatest similarity to M. septentrionale LMG 23930T on their concatenated recA, glnll and rpoB sequences. All isolates grouped closely together for their nifH, nodA and nodC sequences, clearly separate from all other rhizobia in the GenBank database. None of the type strains closest to the Sophora isolates based on 16S rRNA sequence similarity nodulated Sophora microphylla but they all nodulated their original host. Twenty one Sophora isolates selected from the different 16S rRNA groupings produced N2-fixing nodules on three Sophora spp. but none nodulated any host of the type strains for the related species. DNA hybridisations indicated that these isolates belong to novel Mesorhizobium spp. that nodulate NZ native Sophora species

Mesorhizobium waimense sp. nov. isolated from Sophora longicarinata root nodules and Mesorhizobium cantuariense sp. nov. isolated from Sophora microphylla root nodules

In total 14 strains of Gram-stain-negative, rod-shaped bacteria were isolated from Sophora longicarinata and Sophora microphylla root nodules and authenticated as rhizobia on these hosts. Based on the 16S rRNA gene phylogeny, they were shown to belong to the genus Mesorhizobium, and the strains from S. longicarinata were most closely related to Mesorhizobium amorphae ACCC 19665(T) (99.8-99.9 %), Mesorhizobium huakuii IAM 14158(T) (99.8-99.9 %), Mesorhizobium loti USDA 3471(T) (99.5-99.9 %) and Mesorhizobium septentrionale SDW 014(T) (99.6-99.8 %), whilst the strains from S. microphylla were most closely related to Mesorhizobium ciceri UPM-Ca7(T) (99.8-99.9 %), Mesorhizobium qingshengii CCBAU 33460(T) (99.7 %) and Mesorhizobium shangrilense CCBAU 65327(T) (99.6 %). Additionally, these strains formed two distinct groups in phylogenetic trees of the housekeeping genes glnll, recA and rpoB. Chemotaxonomic data, including fatty acid profiles, supported the assignment of the strains to the genus Mesorhizobium and allowed differentiation from the closest neighbours. Results of DNA-DNA hybridizations, MALDI- TOF MS analysis, ERIC-PCR, and physiological and biochemical tests allowed genotypic and phenotypic differentiation of our strains from their closest neighbouring species. Therefore, the strains isolated from S. longicarinata and S. microphylla represent two novel species for which the names Mesorhizobium waimense sp. nov. (ICMP 19557(T)=LMG 28228(T)=HAMBI 3608(T)) and Mesorhizobium cantuariense sp. nov. (ICMP 19515(T)=LMG 28225(T)=HAMBI 3604(T)), are proposed respectively

Pollination of Pagamea duckei Standl. (Rubiaceae): a functionally dioecious species

The floral biology, pollination and breeding system of Pagamea duckei Standl. (Rubiaceae) were studied at the Reserva Biológica da Campina, Manaus, Amazonas, Brazil. Floral morphology suggested that P. duckei is a distylous species. However, crossing experiments revealed that it is functionally dioecious. The flowers are actinomorphic, yellowish, produce nectar and a sweet odor, which is more intense in the morning. Anthesis started in the morning between 5.00 and 6.00 AM and extended until dusk, when the corolla tube abscissed. The flowers were visited mostly by bees of the genus Melipona. Pagamea duckei is not agamospermic and thus needs pollen vectors for effective pollination. The results of this study strengthen the idea that, in Pagamea, species with distylous flower morphology are actually functionally dioecious

Germination of Sophora seeds after prolonged storage

Germination of Sophora seeds 24–40 years old from New Zealand (8 species), Chile (2 species), Lord Howe Island (1 species), and Hawai’i (1 species), and of fresh seed from trees established using seeds from the same seed lots, was assessed. Germination was rapid for most seed lots, with, on average, fresh seed having high germination (77– 94%) and stored seed low germination (0–40%). Exceptions to this were old S. chrysophylla seed, which had unusually high germination (84%), and fresh S. longicarinata seed, which had unusually low germination (24%). The results provide further support for the role of long-distance oceanic dispersal for the distribution of Sophora sect. Edwardsia around the Southern Hemisphere, and also suggest that long-term seed storage could be used for the ex situ management of Sophora populations. The results also highlight some intriguing ecological correlates of germination that warrant further study

Threatened and uncommon plants of New Zealand

A reappraisal of the conservation status of the indigenous New Zealand vascular plant flora is presented. The list comprises 792 taxa (34% of New Zealand’s total indigenous vascular flora) in the following categories: Extinct 4 taxa, Acutely Threatened 122 taxa (comprising 47 taxa Nationally Critical, 54 Nationally Endangered, 21 Nationally Vulnerable), Chronically Threatened 96 taxa (comprising Serious Decline 26 taxa, Gradual Decline 70 taxa), At Risk 499 taxa (comprising Sparse 126 taxa, Range Restricted 373 taxa), Non-resident Native 26 taxa (comprising Vagrant 16 taxa, Colonist 10 taxa), and Data Deficient 45 taxa. A further 208 plants are listed as Taxonomically Indeterminate, being those which might warrant further conservation attention once their taxonomic status is clarified. A further 31 named taxa and 18 rated as Taxonomically Indeterminate, and previously considered to be threatened and/or uncommon, are removed from this updated listing. A concordance of plant names is provided. The lists presented use a new threat classification system developed by the New Zealand Department of Conservation for sole use within this country. This paper represents the first time the entire known indigenous vascular flora has been assessed from a conservation perspective since the mid 1970s. A brief analysis of the patterns of rarity exhibited by the taxa listed is presented

Genetic diversity and nitrogen fixation of mesorhizobia symbionts of New Zealand endemic Sophora species

Forty-four rhizobial isolates from New Zealand endemic Sophora species growing in natural conditions were characterised and the effectiveness of selected isolates with regard to growth and N2 fixation of different Sophora species was tested. Sequences for the housekeeping genes (concatenated recA, gln11 and rpoB) of the isolates were diverse but sequences for their symbiosis genes (nifH and nodC) were similar. Generally, isolates from the same field site showed similar housekeeping gene sequences. All isolates were Mesorhizobium. Twenty-six of the isolates aligned with Mesorhizobium species previously isolated from New Zealand native Sophora on the basis of their housekeeping gene sequences, but 18 isolates separated into two groups and a pair of isolates clearly separated from all Mesorhizobium type strains. DNA–DNA hybridisations indicated that isolates in the two groups could belong to two novel Mesorhizobium species. Rhizobial isolates with different housekeeping gene sequences (but similar symbiosis gene sequences) gave similar increases in dry weight and total N content of four Sophora species under glasshouse conditions