Fig 1.
Proportion of D. wrightii and A. palmeri flowers containing nectar microbes (bacteria and fungi; one nectar sample per flower).
Nectar was collected from plants in field or greenhouse environments, at different time points relative to anthesis, and with or without exclusion of flower visitors ("sleeve", "no sleeve"). Different letters assigned within a time category indicate statistically significant differences (Tukey HSD, p < 0.05).
Fig 2.
Concentration of colony forming units (CFU) in D. wrightii nectar collected before and after anthesis from plants with and without flower visitor exclusion (N = 14, 47, 12, 24 for -1 h/sleeve, -1 h/no sleeve, +16 h/sleeve and +16 h/no sleeve, respectively).
Different letters indicate significant differences (Tukey HSD, p < 0.05).
Fig 3.
Change in abundance of nectar microbes in D. wrightii flowers during one flowering season (31 May (5/31)– 16 October (10/16), 2013).
Nectar was collected from plants in the field 1 h before anthesis and without exclusion of flower visitors. (A) Proportion of D. wrightii nectar samples with microbes (N = 9 each, except for 25 June, 19 August and 16 October, with N = 8, 5, and 8, respectively). (B) Proportion of agar plates showing microbe growth (N = 72 each, except for 25 June, 19 August and 16 October, with N = 64, 40, and 64, respectively). Dashed lines describe second-order polynomial regressions. Different letters indicate significant differences between collection dates (GLM, p < 0.05).
Table 1.
Effects of growing environment, age and flower visitors on nectar microbe community composition in Datura wrightii and Agave palmeri in southeastern Arizona.
Table 2.
Top BLAST matches (genera) for the most common bacteria and all fungi isolated from nectar of D. wrightii and A. palmeri (see S1 Table for full list and details).
Taxa are presented in decreasing order of abundance as isolated from D. wrightii. (%) = isolates relative to total isolates of bacteria (above) or fungi (below).
Fig 4.
Concentration of colony forming units in A. palmeri nectar.
(A) CFU concentration in the nectar of 0, 1, 2, and 3 d old A. palmeri flowers with flower visitor exclusion (N = 2, 3, 3, and 7, respectively). (B) CFU concentration in the nectar of 0, 1, 2, and 3 d old A. palmeri flowers without flower visitor exclusion (N = 5, 12, 8, and 8, respectively).
Fig 5.
Richness of nectar microbes in D. wrightii and A. palmeri flowers.
(A) Species accumulation curve for fungi in D. wrightii nectar samples (N = 59 isolates). (B) Species accumulation curve for fungi in A. palmeri nectar samples (N = 16 isolates). (C) Species accumulation curve for bacteria in D. wrightii nectar samples (N = 210 isolates). (D) Species accumulation curve for bacteria in A. palmeri nectar samples (N = 60 isolates). Figures show the number of fungi and bacteria species observed (here estimated as OTU) (Mao Tau; black lines), lower and upper 95% confidence intervals (light gray lines), and bootstrap estimate of richness (dashed lines).
Fig 6.
Community analysis of nectar microbe communities for D. wrightii and A. palmeri.
Figure shows the results of non-metric multidimensional scaling based on Jaccard's index computed with non-singleton OTU only, and ANOSIM results for (A) bacterial (N = 31 and 47 for A. palmeri and D. wrightii, respectively) and (B) for fungal communities (N = 8 and 39 for A. palmeri and D. wrightii, respectively).