1. ROOTS The Hidden Secrets of Plants by John G. Mexal NMSU

2. Roots -- How Big is the Problem? Rye plant (Secale cereale)

3. Roots Structures Structures Fate of roots Fate of roots Role of symbiosis Role of symbiosis Types of symbiosis Types of symbiosis Inoculation Inoculation Response to inoculation Response to inoculation

4. Root Structures Radicle Radicle Taproot: primary root; develops from radicle Taproot: primary root; develops from radicle Lateral roots: Lateral roots: 1 o develop from taproot. 1 o develop from taproot. 2 o develop from 1 o lateral root 2 o develop from 1 o lateral root Feeder roots: short roots Feeder roots: short roots Root hairs Root hairs

5. Root Structures Adventitious Roots Adventitious Roots Roots occurring where they are not normally found. Roots occurring where they are not normally found. Example: Anchor roots of corn. Example: Anchor roots of corn. Important in asexual propagation (rooting) Important in asexual propagation (rooting)

6. Developing Root Stern 2006

7. Root Cross Section

8. Fate of Feeder Roots / Wilson 1984

9. Roots Contrary to their image, there are more good germs than bad germs. It’s just that the bad germs get all the publicity.

10. Symbiosis Definitions Symbiosis: literally; living together Parasitism Parasitism Commensalism Commensalism Mutualism Mutualism

11. Symbiosis Definitions Symbiosis: literally; living together Parasitism: living together where one benefits at the expense of the other. Parasitism: living together where one benefits at the expense of the other. Emroy Shannon

12. Symbiosis Definitions Symbiosis: literally; living together Parasitism: Parasitism: Commensalism: living together where one benefits, but the other is unaffected, e.g. epiphytes, bromeliads. Commensalism: living together where one benefits, but the other is unaffected, e.g. epiphytes, bromeliads.

13. Trudi Schaper Symbiosis Definitions Symbiosis: literally; living together Parasitism: Parasitism: Commensalism: Commensalism: Mutualism: living together Mutualism: living together where both parties benefit, e.g. lichen.

14. Role of Symbionts in Mutualism

15. Types of Mutualism

16. Symbiosis Plant:Plant Interactions Nitrogen Fixing (certain species) Nitrogen Fixing (certain species) Mycorrhizas (nearly all plants) Mycorrhizas (nearly all plants) Endophyte (antifeedant in grasses) Endophyte (antifeedant in grasses) Acremonium on fescue and ryegrass Acremonium on fescue and ryegrass http://www.noble.org/Ag/Research/Articles/TallFescueToxicity/Index.htm

17. Vegetation TypeHeath/ Conifer Deciduous Grassland Tundra MycorrhizaEricoid Ectomycorrhiza Endomycorrhiza Limiting Nutrient N N/P N/P P Increase in latitude or altitude Symbiosis Mycorrhiza: ‘Fungus Root’ After Read 1984

18. Symbiosis Mycorrhiza: ‘Fungus Root’ Coralloid Mycorrhiza Mycorrhizal Roots Uninfected Roots Live Root Hairs Dead Root Hairs Hyphae

19. Ectomycorrhizas Ectomycorrhizas Swollen, forked fine roots Swollen, forked fine roots Fungal mantle Fungal mantle Hartig net Hartig net No intracellular hyphae No intracellular hyphae Roots

20. Roots- ectomycorrhizas Mechanical Barrier Chemical Barrier Absence of root exudates required by pathogens Presence of antagonistic rhizospere microoganisms Absence of root exudates required by pathogens

21. Ectomycorrhiza development

22. Endomycorrhizas Endomycorrhizas No obvious external root modification No obvious external root modification No mantle or Hartig net No mantle or Hartig net Extensive intracellular hyphae Extensive intracellular hyphae Presence of arbuscules, vesicles, & chlamydospores Presence of arbuscules, vesicles, & chlamydospores Roots

23. Endomycorrhizas Arbuscules Spores Hyphae

24. Symbiont Inoculation Symbiont Inoculation Spores Spores Mycelium Mycelium Inoculated roots Inoculated roots Roots

25. Response to Inoculation IlexCitrus

26. Nitrogen Fixation Nitrogen Fixation Rhizobium + legumes Rhizobium + legumes Frankia + various families Frankia + various families Russian olive Russian olive Alder Alder Mt. mahogany Mt. mahogany Roots

27. Globally, 140 billion kg N fixed/ yr by symbiotic organisms Atmosphere = 78% N 2 Atmosphere = 78% N 2 Convert N 2 gas into amino acids Convert N 2 gas into amino acids Legumes + Bacteria Legumes + Bacteria (Rhizobium) (Rhizobium) Alder + Actinomycete Alder + Actinomycete (Frankia) (Frankia) Cycads + Blue green algae Cycads + Blue green algae (Nostoc) (Nostoc) 0 lb N/ac175 lb N/ac Symbiosis Nitrogen Fixation

28. 0 lb N/ac 175 lb N/ac Rhizobium on soybean

29. Frankia on Alnus

30. Roots-- Terms to Know Radicle Radicle Taproot (primary root) Taproot (primary root) Lateral roots Lateral roots 1 o 1 o 2 o 2 o 3 o 3 o Root hairs Root hairs Feeder roots Feeder roots Adventitious roots Adventitious roots Symbiosis Symbiosis Mutualism Parasitism Commensalism Actinorhiza (Frankia) Actinorhiza (Frankia) N 2 Fixing (Rhizobium) N 2 Fixing (Rhizobium) Endophyte (grasses) Endophyte (grasses) Mycorrhiza Mycorrhiza Endo- --Ecto-

31. Nursery Inoculation

32. Roots Response to Inoculation Nursery-Increased size -Increased value -Decreased culls Field-Improved survival -Improved growth -Altered mycoflora

33. Response to Inoculation

34. Response to Inoculation /Pinus radiata)

35. Killing Trees Mycorrhizal Inoculation + Fertilization/ Scott-Lifland 2000 Trunk Diameter (cm) Schinus molle MycorTree Injectable PHC BioPak 59 g nitrogen Mycor Tree Saver PHC BioPak Southwest Trees & Turf 9/’00