Brachypodium invasion in California may be facilitated by rhizosphere microbes

Transcription

1 Brachypodium invasion in California may be facilitated by rhizosphere microbes Emma L. Aronson, Chelsea Carey, Jon Botthoff, and Pilar Catalan University of California, Riverside Universidad de Zaragoza 1

2 Brachypodium distachyon considered invasive in CA UC Herbaria 2

3 Brachypodium distachyon densities San Diego County, CA, USA Zaragoza, Spain 3

4 Brachypodium distachyon is really 3 species B. distachyon B. staceii B. hybridum Catalan et al

5 Drivers of Invasion Enemy release Exploitation of naïve community Mutualists co- invade 5 5

6 Drivers of Invasion Enemy release Exploitation of naïve community Mutualists co- invade Some combination of these and other factors 6 6

7 Objective To better understand what is driving invasion by Brachypodium annual spp., in CA by investigating their microbiome in their native range May lead to better understanding of past invasion by Bromus annual spp. Assist with preventing or controlling invasions 7

8 Hypotheses Grass root microbiomes are a subset selected from their surrounding rhizosphere communities, which in turn select from bulk soil communities Closely related genera differ in their root and rhizosphere microbial communities 8

9 Methods Collected Brachypodium spp. and co- occurring Bromus spp. in May 2014 and 2015 For Brachypodium spp. we collected B. distachyon and B. hybridum (here reported together) For Bromus spp. we collected B. rubens and B. madritensis (here reported together) Collections were performed in Spain, within the native range, and Califonia, the invaded range for both genera 9

10 Plant sampling scheme Roots Roots/rhizosphere Bulk soil 10

11 Molecular methods DNA extracted using MoBio PowerSoil kit PCR for V3 and V4 regions of 16S rrna gene Sequenced via Illumina MiSeq Analyzed via QIIME and R 11

12 Results: By sample type across locations and years SampleType Bulk Core 2 RhizosphereOnly NMDS2 0 2 Plant RootOnly RootRhizosphere Bra_distachyon Brachypodium distachyon Bra_hybridum Brachypodium hybridum Bro_rubens Bromus rubens NMDS1 None 12

13 Results: Locations differed within Spain 0.5 Location NMDS NMDS1 13

14 Results: Microbial communities by plant genus Bulk soil 1.0 NMDS Genus Species Brachypodium Bromus NMDS1 14

15 Results: Microbial communities by plant genus Bulk soil 1.0 NMDS NMDS NMDS1 Species Brachypodium Bromus Root/rhizosphere soil Genus Species Brachypodium Bromus NMDS1 15

16 Results: Microbial communities by plant genus Bulk soil Root only 1.0 Rhizosphere soil NMDS Genus Species Brachypodium Bromus NMDS1 16

17 Results: Core microbiome within Spain Brachypodium Root/Rhizosphere Bromus Root/Rhizosphere 17

18 Core microbiome CA to Spain 18 18

19 Conclusions Invasive grass root endophyte communities are unique between plant genera, while nearby soil communities are not As the bacteria show little overlap between Spain and CA, we have an indication of the Enemy Release Hypothesis 19

20 Impact These data may lead to identification of beneficial or detrimental root endophytes May aid in the understanding of, and biocontrol for, these grasses in California. 20

21 Continuing research Additional collections were performed in 2015 & 2016 Matched collections performed in Spain and California Roots completely separated from rhizosphere in all 2015/2016 samples In the process of sequencing these samples now. 21

22 Acknowledgements Collaborators Ruben and others in the Catalan Lab at Escuela Politechnica de Huesca Edie and Mike Allen at UC Riverside The Aronson Lab Graduate student Brooke Pickett Undergraduate students Andres Rodriguez, Taryn Barsotti, and Samantha Chow Funding Source USDA NIFA AFRI SEED grant 22

23 Questions? 23

24 Results Spain NMDS Description Bulk RootOnly RootRhizosphere NMDS1 24

25 Results: Overlapping species and years Plant NMDS Year Bra_distachyon Bra_hybridum Bro_rubens None NMDS