Flavonoids' presence in sorghum roots may lead to frost-resistant crop


Date:
August 13, 2020
Source:
Penn State
Summary:
Flavonoid compounds -- produced by the roots of some sorghum
plants - - positively affect soil microorganisms, according
to researchers, who suggest the discovery is an early step in
developing a frost-resistant line of the valuable crop for North
American farmers.



FULL STORY ========================================================================== Flavonoid compounds -- produced by the roots of some sorghum plants
- - positively affect soil microorganisms, according to Penn State
researchers, who suggest the discovery is an early step in developing
a frost-resistant line of the valuable crop for North American farmers.


==========================================================================
That is important because sorghum is a crop that can respond to climate
change because of its high water- and nitrogen-use efficiency, according
to Surinder Chopra, professor of maize genetics, and Mary Ann Bruns,
professor of soil microbiology. A close relative to corn, it is the
fifth most valuable cereal crop globally.

"Sorghum can be used for human food and animal feed and also can
be grown as a bioenergy crop, producing more ethanol than corn when
grown on marginal lands," they said. "Sorghum is better adapted than
corn to stresses such as drought, salinity and heat. But increased
sorghum production requires increasing its tolerance to chilling and
frost stress, and this is especially true for the northeastern U.S."
Showing red flavonoids To reach its full potential, sorghum needs to grow
five months after being planted in the first week of June. If a frost
occurs in early October -- which is not unusual in the U.S. Northeast
-- farmers can be devastated. Because sorghum is so sensitive to being
chilled, even a mild frost or an early cold snap can kill the crop.

Earlier studies by Chopra's research group in the College of Agricultural Sciences showed that sorghum produces potent flavonoids in its leaves
when exposed to stresses such as fungi, insect feeding or frost. These flavonoids can allow the plant to adapt and survive. Bruns group has been working on understanding soil microbiomes in various stressed ecosystems.



========================================================================== Together, the researchers are testing whether interactions between those flavonoids and microorganisms in the root zone can lead to the development
of sorghum varieties and compatible soil microbial additions to provide resistance to cold and frost. A collaborative effort between the two
research groups enables them to connect the prevalence of plant-associated microbiomes, plant genetics and flavonoids.

In this study, researchers found evidence that plant genetic variation influences root flavonoids and the composition of the soil microbial
community, and that low temperatures affect these relationships. In
findings recently published in Phytobiomes Journal, they contend that plant-microbe interactions and secondary metabolite production may be
important components to include for selective breeding of sorghum for
frost stress tolerance.

"We think that the flavonoids can provide the needed tolerance against the stress of cold and frost," Bruns and Chopra said. "In addition, certain microorganisms present in the soil can interact with flavonoids to provide adaptability to the plant when it perceives cold or frost above ground."
The researchers grew selected lines of sorghum at Penn State's Russell E.

Larson Agricultural Research Center at Rock Springs from seeds they
acquired from the Grain, Forage and Bioenergy Research Laboratory
maintained by the U.S.

Department of Agriculture's Agricultural Research Service in Lincoln,
Nebraska.

Of those "near-isogenic" lines of sorghum -- alike except for two genes involved in the production of flavonoids -- one set of lines inherently produced flavonoids, the second set lacked genes to produce flavonoids,
and the third type only produced flavonoids when the plants were exposed
to stress such as frost and fungal pathogens.



========================================================================== Researchers analyzed the community of microorganisms in the soils
surrounding the roots to see if the presence or absence of flavonoids
in the roots of some of the sorghum plants impacted communities of fungi
and bacteria. Lead researcher Mara Cloutier, doctoral candidate in soil
science and biogeochemistry, led the evaluation of microbiomes in the
vicinity of the roots before and after a late-season frost.

Seed multiplication plot The researchers analyzed roots for total
flavonoids, total phenolics and antioxidant activity to determine whether sorghum genetic variation influenced root flavonoid concentrations and
soil microbial communities. The researchers wanted to identify how frost affected these relationships.

"We found that a greater number of bacterial strains were correlated with
total flavonoids compared with fungal species," she said. "Collectively,
this study provides evidence that plant genetic variation influences
root flavonoids and the soil microorganism community composition in the vicinity of the plant roots, and that these relationships are affected
by frost." Also involved in the research were Debamalya Chatterjee,
Dinakaran Elango and Jin Cui, graduate students in plant science.

The Sun Grant Initiative and the U.S. Department of Agriculture's National Institute of Food and Agriculture funded this research.


========================================================================== Story Source: Materials provided by Penn_State. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Mara Cloutier, Debamalya Chatterjee, Dinakaran Elango, Jin Cui,
Mary Ann
Bruns, Surinder Chopra. Sorghum Root Flavonoid Chemistry,
Cultivar, and Frost Stress Effects on Rhizosphere Bacteria
and Fungi. Phytobiomes Journal, 2020; PBIOMES-01-20-0 DOI:
10.1094/PBIOMES-01-20-0013-FI ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200813123612.htm

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