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RUIZ, O. A.

Publications and source records attributed to RUIZ, O. A..

2 recordsLinked to original sources
bioRxiv2020

Characterization of alkaline stress tolerance mechanisms in Lotus forage species modulated by Pantoea eucalypti

This study was designed to elucidate the physiological responses of three Lotus forage accessions to alkaline stress and the influence of the inoculation of a Pantoea eucalypti endophyte strain on its mitigation. One-month-old diploid accessions of Lotus corniculatus (Lc) and Lotus tenuis (Lt), and the interspecific hybrid LtxLc obtained from these parental accessions, were exposed to alkaline stress (pH 8.2) by the addition of NaHCO3 10 mM to the nutrient solution for 2 weeks. The results indicated that Lt and the LtxLc hybrid are alkaline-tolerant compared to Lc, based on the observation that their dry mass is not reduced under stress, and symptoms of chlorosis do not appear on leaf blades, in contrast to observations of the Lc accession subjected to identical growth and stress conditions. In Lc and LtxLc accessions, the Fe2+ concentration decreased in the aerial part under stress and increased in the roots. Interveinal chlorosis observed in the youngest leaves of Lc during alkaline treatment was accompanied with a higher reduction of Fe2+ levels in shoots and a higher increment of Fe2+ in roots, compared to the other accession. Plant inoculation also tended to acidify the medium under alkalinity, contributing to Fe accumulation in the roots. Moreover, the inoculation caused a considerable increase in Fe2+ content in shoots in all three Lotus forage species under alkaline treatment. Fv/Fm and PIABS were only reduced in Lc under alkaline treatment. Inoculation reverted this effect and improved the ABS/RC and DIo/RC ratios in all three accessions. In addition, under alkaline conditions, Lc dissipated more energy than control plants. Expression of the metal-transporting gene NRAMP1 increased in the inoculated Lc accession under stress, while remaining unmodified in Lt and LtxLc hybrid. Altogether, the results obtained make clear the importance of inoculation with P. eucalypti, which contributed significantly to the mitigation of alkaline stress. Thus, all the results provide useful information for improving alkaline tolerance traits in Lotus forage species and their interspecific hybrids.

plant biology↗
bioRxiv2020

Contrasting response of two Lotus corniculatus L. accessions to combined waterlogging-saline stress

Waterlogging and salinity impair crops growth and productivity worldwide, being their combined effects larger than the additive effects of both stresses separately. Recently, a new Lotus corniculatus accession has been collected from a coastal area with a high frequency of waterlogging-saline stress events. This population is diploid and has potential to increase nutritional values of Lotus cultivars used as forages. Due to its environmental niche, we hypothesize that this accession would show a better adaptation to combined waterlogging-saline stress compared to another commonly used tetraploid L. corniculatus (cv. San Gabriel). Shoot and root growth under waterlogging, salinity and combined waterlogging-saline treatments were addressed, together with chlorophyll fluorescence and gas exchange measurements. Results showed that salinity and waterlogging effects were more severe for the tetraploid accession, being the differences larger under the combined stress condition. In addition, Na+, Cl- and K+ concentrations were measured in young and old leaves, and in roots. A larger accumulation of Na+ and Cl- was observed under both saline and combined stress treatments for the tetraploid L. corniculatus, for which ion toxicity effects were evident. The expression of the NHX1 and CLC genes, coding for Na+ and Cl- transporters respectively, was only increased in response to combined stress in the diploid L. corniculatus plants, suggesting that ion compartmentalization mechanisms were induced in this accession. As a conclusion, the recent characterized L. corniculatus might be used for the introduction of new tolerant traits to combined stresses, in other Lotus species used as forage.

plant biology↗