The role of species’ interactions in structuring biological communities remains unclear. Mutualistic symbioses, involving close positive interactions between two distinct organismal lineages, provide an excellent means to explore the roles of both evolutionary and ecological processes in determining how positive interactions affect community structure. In this study, we investigate patterns of co-diversification between fungi and algae for a range of New Zealand lichens at the community, genus, and species levels and explore explanations for possible patterns related to spatial scale and pattern, taxonomic diversity of the lichens considered, and the level sampling replication. We assembled six independent datasets to compare patterns in phylogenetic congruence with varied spatial extent of sampling, taxonomic diversity and level of specimen replication. For each dataset, we used the DNA sequences from the ITS regions of both the fungal and algal genomes from lichen specimens to produce genetic distance matrices. Phylogenetic congruence between fungi and algae was quantified using distance-based redundancy analysis and we used geographic distance matrices in Moran’s eigenvector mapping and variance partitioning to evaluate the effects of spatial variation on the quantification of phylogenetic congruence. Phylogenetic congruence was highly significant for all datasets and a large proportion of variance in both algal and fungal genetic distances was explained by partner genetic variation. Spatial variables, primarily at large and intermediate scales, were also important for explaining genetic diversity patterns in all datasets. Interestingly, spatial structuring was stronger for fungal than algal genetic variation. As the spatial extent of the samples increased, so too did the proportion of explained variation that was shared between the spatial variables and the partners’ genetic variation. Different lichen taxa showed some variation in their phylogenetic congruence and spatial genetic patterns and where greater sample replication was used, the amount of variation explained by partner genetic variation increased. Our results suggest that the phylogenetic congruence pattern, at least at small spatial scales, is likely due to reciprocal co-adaptation or co-dispersal. However, the detection of these patterns varies among different lichen taxa, across spatial scales and with different levels of sample replication. This work provides insight into the complexities faced in determining how evolutionary and ecological processes may interact to generate diversity in symbiotic association patterns at the population and community levels. Further, it highlights the critical importance of considering sample replication, taxonomic diversity and spatial scale in designing studies of co-diversification.

A number of parameters which have been reported to influence genetic transformation via Agrobacterium-mediated transformation method were evaluated to increase the frequency of transformation of cabbage (Brassica oleracea subsp. capitata) cv. KY Cross with AtHSP101 gene. The binary vector pCAMHSP was designed and mobilized into two Agrobacterium tumefaciens strains C58 and GV2260. The study was carried out on hypocotyl and shoot tip explants of cabbage cv. KY Cross. Transformation parameters optimized were pre-culture medium, acetosyringone application, bacterial density and inoculation time. The polymerase chain reaction (PCR) assay and production of mRNA of AtHSP101 gene were confirmed by reverse transcription-polymerase chain reaction (RT-PCR). The expression of LacZ gene in the transgenic plants also showed that it could be applied as a plant transformation reporter gene in genetic transformation studies. Multiple shoot regeneration of hypocotyl and shoot tip explants of cabbage after co-cultivation with Agrobacterium was optimized and medium containing 2 mg/L BAP was observed to be the best for shoot regeneration after cocultivation. In this study, 45% and 32.5% transformation efficiencies were achieved for hypocotyl and shoot tip explants, respectively using the optimized procedure.

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