In a new study published in New Phytologist, Chen Lin and colleagues have unlocked the secret behind deepwater rice’s extraordinary ability to survive and even thrive in flooded conditions. This discovery could lead to a more secure global food supply as climate change threatens crop yields worldwide.
The researchers focused on the fascinating ability of deepwater rice to grow special roots known as aquatic adventitious roots (AAR) in response to flooding. These roots enable the plant to obtain vital oxygen and nutrients, even when submerged in water for extended periods.
By examining near genetically identical lines of deepwater rice, the scientists discovered that the same genetic traits responsible for the plant’s incredible shoot elongation also promote the development of aquatic adventitious roots. They observed that two distinct types of aquatic adventitious roots (AR1 and AR2) emerge at different times, with unique morphological and anatomical traits, allowing them to adapt to different flooding conditions.
Remarkably, the researchers found that the second type of root (AR2) is better suited to long-term flooding, as it possesses a higher elongation capacity and desiccation tolerance. This discovery suggests that AR2 could play a crucial role in the plant’s evolutionary defence strategy against periodic submergence.
The researchers believe that their findings could have far-reaching implications for food security. As extreme weather events and flooding become more common due to climate change, understanding the mechanisms behind flood-tolerant crops like deepwater rice will be vital for ensuring a stable and sustainable global food supply.
Lin and colleagues conclude:
We propose that AR2 in deepwater rice could function as an evolutionary defence strategy to tackle periodic and long-term submergence. The morphological and anatomical traits suggested that AR2 is better adapted to flooding than AR1. The leaf sheath was the key factor influencing growth rate, elongation capacity and root diameter of AR2. As compared to paddy rice (T65), NIL-1 and NIL-12 produced more AR2 during flooding, indicating that key genes controlling AR2 development are included in QTL1 and QTL12. We suggest to further investigate the genes in these two QTLs regulating AR2 growth. Moreover, the functions of AR2 with respect to water and nutrient uptake during partial submergence have to be unravelled to justify introducing aquatic adventitious roots in modern cultivars for areas experiencing long-term shallow flooding.Lin et al . 2023
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Lin, C., Ogorek, L.L.P., Liu, D., Pedersen, O. and Sauter, M. (2023) “A quantitative trait locus conferring flood tolerance to deepwater rice regulates the formation of two distinct types of aquatic adventitious roots,” New Phytologist, 238(4), pp. 1403–1419. Available at: https://doi.org/10.1111/nph.18678.