Physiological Responses to Salt Stress at the Seedling Stage in Wild (<i>Oryza rufipogon</i> Griff.) and Cultivated (<i>Oryza sativa</i> L.) Rice
2024
Jacopo Trotti | Isabella Trapani | Federica Gulino | Maurizio Aceto | Miles Minio | Caterina Gerotto | Erica Mica | Giampiero Valè | Roberto Barbato | Cristina Pagliano
Domesticated rice <i>Oryza sativa</i> L. is a major staple food worldwide, and the cereal most sensitive to salinity. It originated from the wild ancestor <i>Oryza rufipogon</i> Griff., which was reported to possess superior salinity tolerance. Here, we examined the morpho-physiological responses to salinity stress (80 mM NaCl for 7 days) in seedlings of an <i>O. rufipogon</i> accession and two Italian <i>O. sativa</i> genotypes, Baldo (mildly tolerant) and Vialone Nano (sensitive). Under salt treatment, <i>O. rufipogon</i> showed the highest percentage of plants with no to moderate stress symptoms, displaying an unchanged shoot/root biomass ratio, the highest Na<sup>+</sup> accumulation in roots, the lowest root and leaf Na<sup>+</sup>/K<sup>+</sup> ratio, and highest leaf relative water content, leading to a better preservation of the plant architecture, ion homeostasis, and water status. Moreover, <i>O. rufipogon</i> preserved the overall leaf carbon to nitrogen balance and photosynthetic apparatus integrity. Conversely, Vialone Nano showed the lowest percentage of plants surviving after treatment, and displayed a higher reduction in the growth of shoots rather than roots, with leaves compromised in water and ionic balance, negatively affecting the photosynthetic performance (lowest performance index by JIP-test) and apparatus integrity. Baldo showed intermediate salt tolerance. Being <i>O. rufipogon</i> interfertile with <i>O. sativa</i>, it resulted a good candidate for pre-breeding towards salt-tolerant lines.
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