roots micorhyzes and soil microorganisms

In another thread I wrote: “root system is interacting cooperating to competiting with all soil microorganisms be they insects worms bacterias funghi…”

A few years ago I corresponded with Hans van Hage about his no chemical rose nursery and he pointed to his use of micorhyzes.

I did try some on sowing flats and the roots instead of long running intertwined on trays bottom were shorter dense very ramified holding little soil balls that made transplanting and further growth a lot easier.

This effect of microorganisms on root morphology is consistent. As well as micorhyzes-disease resistance correlation.

By the way micorhyzes are predatory funghi that kill other microorganisms sharing the nutrients with host plant that provide them other nutrients.
These micorhyzes rely on an biologically active soil. Chemicals including high nutrients do deplete microorganism populations.
One can think that among micorhyze provided nutrients there are some quite helpful molecules.

Cooperation ability is known to be very variable from none to absolute interdependence so that one should consider breeding for roots that have a better ability to cooperate with micorhyzes.

Scagel C F. Cultivar specific effects of mycorrhizal fungi on the rooting of miniature rose cuttings. Journal of Environmental Horticulture, 2001,19(1): 15-20.

The benefits from root colonization by mycorrhizal fungi are thought to be highest when colonization occurs as early as possible during plant growth. We assessed whether addition of VA mycorrhizal fungi (VAMF) inoculum into rooting medium during cutting propagation would increase the quantity of rooting and the quality of rooted cuttings for five different cultivars of miniature roses (Rosa spp.). Four weeks after cuttings were stuck, the number of cuttings with roots for two cultivars that normally take longer to root, increased with addition of VAMF inoculum into the rooting medium. The combination of hormone treatment and VAMF inoculum in the rooting medium increased the number of rooted cuttings and the number of roots per cutting for three cultivars when compared to cuttings that only received hormone treatment. Increases in root initiation and root growth of cuttings rooted in medium containing VAMF inoculum were not always associated with increased levels of root colonization by VAM fungi. Our results indicate that although adding VAMF inoculum into the rooting medium does not always increase root initiation, in some cultivars the combination of VAMF inoculum and rooting hormones can increase root initiation and potentially increase the quality of rooted cutting produced.

Rooting of Rose Micro-Cuttings Derived from In Vitro Culture
by Claude Richer and Christian Bédard1.
1 Nursery Jardinire du Nord, Saint-Flix-de-Valois (Quebec).

Propagating plants on their own roots, either through cuttings or in vitro culture permits the exact reproduction of desired traits. With the cutting method, it takes several years before a new rose cultivar is ready to be placed on the market. New technologies therefore need to be developed to accelerate this process of introducing new cultivars. Direct rooting provides a link between in vitro culture and the conventional cutting technique. Factors such as hormones, the substrate used and mycorrhizal development were studied in four rose varieties in the Explorer Series TM : ‘Lambert Closse’ (LC), ‘Captain Samuel Holland’ (CSH), ‘William Booth’ (WB) and ‘George Vancouver’ (GV).

Journal of the American Society for Horticultural Science [J. Am. Soc. Hort. Sci.]. Vol. 129, no. 5, [np]. Sep 2004.
Changes in Cutting Composition during Early Stages of Adventitious Rooting of Miniature Rose Altered by Inoculation with Arbuscular Mycorrhizal Fungi
Scagel, CF

Many changes in metabolism are known to occur during adventitious root formation, including changes in amino acids, proteins, and carbohydrates. The influence of arbuscular mycorrhizal fungi (AMF) on adventitious rooting of rose was tested by inoculating four cultivars with Glomus intraradices Schenck & Smith. Changes in cutting composition were measured during the initial stages of adventitious root formation. Although there were cultivar-specific differences in response, AMF inoculation generally increased the biomass and number of adventitious roots on cuttings before root colonization was detected. Application of rooting hormone increased this effect. Inoculation with washings also increased the root biomass and number, but only when cuttings were treated with hormone. Changes in cutting composition in response to AMF were detected at 7 to 14 days. Differences in protein concentrations in response to AMF or hormone application were similar, while differences in amino acid and reducing sugar concentrations were not. Concentrations of proteins and amino acids in cuttings at the beginning of the experiment were positively correlated with adventitious rooting, while concentrations of reducing sugars and nonreducing sugars were not correlated with rooting. These results suggests that nitrogen-containing compounds play an important role in adventitious rooting, and that changes in amino acids associated with AMF inoculation were potentially different than those that occurred when cuttings were treated with rooting hormone alone. Carbohydrate concentrations in cuttings were not strongly related of adventitious roots, but reducing sugar may play a role in regulating part of the response of cuttings to AMF. The response of rose cuttings prior to colonization by G. intraradices suggests that AMF-plant signaling events occurred prior to rooting.;129/5/624

Spanish Journal of Agricultural Research Vol 10, No 1 (2012)
Application of arbuscular mycorrhizal fungi on the production of cut flower roses under commercial-like conditions
I. Garmendia, V. J. Mangas

The objective of this work was to study the influence of two arbuscular mycorrhizal fungi (AMF) - Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, and G. intraradices (Schenck & Smith) - on cut flower yield of rose (Rosa hybrida L. cv. Grand Gala) under commercial-like greenhouse conditions. Flower production was positively influenced by G. mosseae inoculation. Both inocula tested caused low levels of mycorrhizal root colonization, with higher percentages in Rosa associated with G. mosseae. Significant improvement of plant biomass or leaf nutritional status was not detected in inoculated plants probably due to the low symbiosis establishment. However, G. mosseae induced an early flowering and slightly increased number of cut flowers relative to non-mycorrhizal controls. It is suggested that an altered carbohydrate metabolism could contribute to this positive effect. Low colonization of rose roots supports the idea that more effort is required to ensure successful application of AMF in ornamental production systems.

This paper includes a bibliography of articles on Roses and mycorrhizae.

Pierre, were you using a brand name product to provide the micorhyzes?

I’ve had good luck using a product called Rootshield here on petunias, celosia, and cleome at the time of transplant into the garden. (Trichoderma harzianum, strain T-22)

I’ve had good luck using a product

Don’t use a commercial product. Go out into the wilds nearby and fetch a bucketful of innoculum by punching some holes in the rhizomatous mat. If you can locate some wild stands of roses then you’ll increase your odds that the micro-critters will be suitable for your own use by snatching the rhizomatous mat from nearby those.

Another approach, possibly suitable for your environs, is to clear cut a field of shrubs to plant your seedlings out in sans tilling.

pH is about the only factor you might fret about. Here the rhizomatous mat is acidic enough to tan leather and remove bumper rust. I mitigate it with dolomite.

Also, poison ivy/sumac/oak roots can easily be part of the mat so protect yourself if you are sensitive to urishiol.

For containers I use a soil-less mix of mostly perlite, some peat and some bark mulch, the lot innoculated with rhizomatous mat. I fertilize with Holly-Tone rose food once a year as an adjunct to Peters and Miracle Grow - not exactly the same thing as rhizomatous mat but I figure the microbes work it out.

Joe Best results I got with preemergence Trichoderma harzianum plus later Rootgrow.
The said Tricho… is a pithium antagonist.
Tricho viride is said to have the better symbiotic abilities.
So I would like to be able to get some Rootshield.

Mycorrhizal fungi are very important to most flowering plants, and have been overlooked by too many gardeners. However, there are differences in the fungi, even regional differences. So, a plant might be able to hook-up with two different species of fungus, but get more benefit from one than the other.

New Phytologist, 93(1): 67-76 (Jan. 1983)
Effects of Two Species of Va Mycorrhizal Fungi on Drought Tolerance of Winter Wheat
Michael F. Allen, Michael G. Boosalis
Roots and soils from western Nebraska fields of native and planted grasslands, and winter wheat of varied fallow-wheat cultivation duration, were evaluated for vesicular-arbuscular (VA) mycorrhizal root infection and spore numbers and types. Increased cultivation decreased percentage mycorrhizal infection in wheat and reduced spore numbers of > Glomus fasciculatus, > the dominant VA mycorrhizal fungus in these soils. Spore numbers of other VA mycorrhizal fungi did not change significantly with cultivation although mean numbers of > G. mosseae > increased with continued wheat production. Water relations and growth were determined for greenhouse-grown non-mycorrhizal, > G. fasciculatus> -infected, and > G. mosseae> -infected wheat in wet and dry soils. Stomatal conductances were higher in mycorrhizal than in non-mycorrhizal plants in both wet and dry treatments. Stomatal closure in mycorrhizal plants occurred at lower leaf water potentials (ψ) and after greater desiccation than in non-mycorrhizal plants, but some leaves of > G. mosseae> -infected plants showed no stomatal response to drought and continued to transpire at ψ as low as -4.1 MPa. Leaf osmotic adjustment was greatest for > G. fasciculatus> -infected plants. Non-mycorrhizal and > G. fasciculatus> -infected plants had equal dry wts in both wet and dry conditions. Infection by > G. fasciculatus > appeared to increase wheat drought tolerance while infection by > G. mosseae > did not.

And, different accessions of a single species may offer different benefits.

HORTSCIENCE 40(2):381-385. 2005.
Influence of Arbuscular Mycorrhizae Indigenous to Peru and a Flavonoid on Growth, Yield, and Leaf Elemental Concentration of ‘Yungay’ Potatoes
Fred T. Davies, Jr. and Constantino M. Calderon
This study shows the benefit of mycorrhiza as biofertilizers on growth, tuber yield, nutrient uptake and PUE of ‘Yungay’ potatoes in low input, sustainable agriculture systems of the Peruvian highlands, it is important to use native mycorrhiza. While some limited studies have been done with nonnative mycorrhiza in Peru (Calderon, 1994; Moreno, 1988), this is the first successful report, to our knowledge, where native mycorrhiza were used as biofertilizers to enhance growth and yield of the important potato cultivar ‘Yungay’. There were differences in plant growth, nutrient uptake and PUE among the AMF isolates. Formononetin also enhanced the growth effectiveness of the two Peruvian mixed isolates.

I think there’s not much chance that a rose growing in a swamp or bog will find its preferred mycorrhizal fungus a dry prairie soil. And a Siberian Rugosa might have as much trouble finding suitable fungi on the Florida coast.


Hi Karl

One can say it is not the best known subject.

So I concur that different micorhyze clones have different host plant affinities and also at times prey target.

But many micorhyzes are host dependent and not so much soil adapted when other soil microorganisms are eventually.
That micorhyzes are predating non subservient to host microorganisms is the key.

This is illustrated by the numerous funghi that develop caps and are tree dependent edible or not; many are just a little less widespread than host trees.

The same micorhyze efficient in my seed flats are in my rose field and in one thousand km north Hans van Hage nursery.

Also that you can plant an inoculated tree and gather mushrooms even out of the tree natural area.

Sometimes the gene-splicers get so carried away with their gee-whiz technology that they forget to think of the consequences.

Genetics and Genomics of Rosaceae (2009) pp. 399, 401
19. Genetic Engineering and Tissue Culture of Roses
T. Debener and L. Hibrand-Saint Oyant
The development of plants resistant to fungal diseases has been one of the major goals of genetic engineering in roses. Thus far, the rice chitinase gene (Marchant et al., 1998b), several genes from Barley (class II chitinase, class IIb-1,3-glucanase and type I ribosome inhibiting protein), the T4-lysosyme from T4 phage (Dohm et ale, 200 1 ) and the Ace-AMP1 gene isolated from onion seeds to enhance powdery mildew resistance (Li et al., 2003) have been inserted into rose. Marchant et ai. (1998b) demonstrated that chitinase activity in the transformed plants increased the resistance of rose to the > Diplocarpon rosae > pathogen whereas for Dohm et al. (2001) only the ribosome inhibiting protein and not the chitinase or the glucanase gene showed a reduction of black spot susceptibility. Transformed rose plants with the T4-lysosyme gene inserted showed reduced powdery mildew disease symptoms (Li et al., 2003). As all theses genes encoded antifungal proteins, the generated transgenic plants may have resistance to a broad range of pathogens (Dohm et al., 2001:). Consequently, the transgenic lines generated by Dohm et al. (2001) were evaluated for resistance to black spot, powdery mildew and downy mildew of roses. Preliminary results show that a number of transgenics show enhanced resistance to these pathogens (Debener unpublished results). Surprisingly, resistance for these three pathogens turns out to be dependent on the strain of the pathogen with some plants being resistant to one strain but susceptible to another and vice versa. In addition plants resistant to powdery mildew may be susceptible to black spot and vice versa indicating that this lytic enzyme gene insertion approach in roses does not necessarily lead to pathogen independent resistance.
Genetics and Genomics of Rosaceae - Google Books

An obvious problem with this technique is that the anti-fungal chitinase, etc. is likely to be as deadly to beneficial mycorrhizae as it is to pathogenic fungi.

It may well be Nature intends there never to be resistance to all three major rose fungi. Maytime seems immune to powdery mildew, but it will definitely black spot. Basye’s Legacy offspring can often be seemingly immune to mildew and highly resistant to black spot, but many rust like old iron skillets. Howard’s Thanksgiving (I LOVED that rose!) never mildewed and seldom black spotted for me, but I finally had to dump it due to terminal rust. It was addicted to it.

I can’t disagree. Sometimes it does seem to be true that we can’t have it all.

How many wild roses, growing in their native habitats, are defoliated by black spot or stunted by mildew? Is rust really harmful to wild roses, as opposed to being merely unsightly?

I just came across this report on mycorrhizae and roses. It may be of some interest.

Like most reports I’ve found, this deals with cultivated types. I still have to wonder how species from widely distant and distinct habitats would respond to different types of mycorrhizae. Roses inhabit deserts and swamps, frigid wastelands and tropical jungles. How can we expect a “one size fits all” solution to the various health problems of cultivated roses derived from such diverse ancestors?

Mycorrhyze habitat is his host roots.That they are more or less host specialized is easy to observe looking at the cap producing ones. Many are tree dependent and follow hosts everywhere they grow. Mushrooms gatherers know.

Species rose strategy is the hide and seek one. Each plant has a different resistance set and these plants are mostly mixed among other plants with another microorganism cortege. We look at the successful ones, be they individuals or species. Trial and error. Die early or do not develop.

That strategy of growing one plant only, removing the deseased and mixing with other plants works quite well in “organic” gardens with the genetically diverse and close to species OGRs.

Much better than for i.e. for the too closely related HTs that where selected away from species and for a few rare features with persistently as much inbreeding as possible.

That is true. However, many Rosa species have been distributed around the world as clean seeds, with little opportunity for finding the most suitable species or race of mycorrhizae. They may grow well enough, but I suspect that they will be less happy and healthy than they would have been if they had stayed at home.

This is also true. Wild roses, at least those I’ve seen, are typically found growing with other plants, rather than as “pure” colonies. Rosa arkansana in Kansas grows among grasses and other plants. R. setigera here in Tennessee sometimes grows into trees, or mingles with other shrubs and bushes. And the various species I saw in California, either in dense forests or along the margins, were scattered among other plants.