You can protect blueberries from cold with some help from the Antarctic

Climate change isn’t just making the average weather warmer, it’s also becoming more unpredictable with wider extremes of weather. In the Mediterranean climatic region of central Chile, this is a problem for blueberry farmers. Sudden cold snaps and water shortages can strike the plants when they’re most vulnerable. Now research by Ian Acuña-Rodríguez and colleagues in South America has found a way to help the blueberries. They’re inoculated with a couple of species of Penicillium found in the Antarctic.

Acuña-Rodríguez and colleagues chose to test two root endophytes, organisms that live with plants, from Antarctica. They reasoned that plants in Antarctica face a few stresses at the same time. There’s cold and, despite the snow, there’s also often drought as the water the plants need is frozen.

The authors had already knew that Penicillium species from roots of Colobanthus quitensis collected from King George Island, just off the tip of the Antarctic peninsula, had been shown to help crops cope with drought stress. Co-author Marco Molina-Montenegro and colleagues, had used these microbes to help lettuce cope with drought stress and published their results in AoB PLANTS.

So the team tested two of the fungi found in the roots, Penicillium rubens, the source of Penicillin, and its sister species P. bialowienzense. If the fungi could help lettuce, the scientists thought it worthwhile to test them in Chile. The tests examined how Highbush Blueberry (Vaccinium corymbosum) reacted to inoculations of the two Penicillium species with differing access to water. To see what effect the endophytes had, they exposed both inoculated and uninoculated plants to one event of one chilly night just above freezing for eight hours every week for a month.

The authors found that while the blueberries did not cope well with the cold, the Penicillium helped the plants cope. This result could have a practical use for farmers in Chile right now. In their article Acuña-Rodríguez and colleagues write, “Established in the last decades, blueberry plantations have exported fruits for more than 100,000 tons, mainly from the Brigitta cultivar. Berries of this cultivar are large, sweet, firm, and resistant to bruising and thus suitable for mechanical harvesting. In addition, they present a long postharvest life retaining the desirable organoleptic properties and edible quality even after 8 weeks of storage. However, all these positive qualities are counteracted by a reduced fruit set, possibly related with a high rate of abortions due to sub-zero temperatures during the spring season. This condition can be worsened as plants of this cultivar are highly susceptible to drought, showing a severe impairment in physiological parameters when water availability is low. Additionally, extreme low temperature events could be frequent during the winter and spring seasons in central Chile… Thus, blueberry is a suitable crop to search and test novel biotechnological solutions for dealing with abiotic stress, particularly drought and cold stress. Our results suggest that functional symbiosis with beneficial microorganisms like some endophytic fungi may be one of these solutions.”

Quite how the endophyte helps the plant is unclear, but Acuña-Rodríguez and colleagues suggest that one possible way is by enhancing plant nutrient uptake rates, particularly nitrogen and phosphorous. These are critical elements in many amino acids and proteins. By increasing access to these elements, the fungi may help the plants source the raw material they need to build a buffer against cold and drought stress.

ORIGINAL ARTICLE

Acuña-Rodríguez, I.S., Ballesteros, G.I., Atala, C., Gundel, P.E. and Molina-Montenegro, M.A. (2022) “Hardening blueberry plants to face drought and cold events by the application of fungal endophytes,” Agronomy https://doi.org/10.3390/agronomy12051000