Physiological and anatomical traits associated with tolerance to long‐term partial submergence stress in the Lotus genus: responses of forage species, a model and an interspecific hybrid

Abstract

Cattle production based on natural pastures is often subject to flooding periods, which affect plant performance and as a result, forage production. Although most forage legumes are not tolerant to flooding, Lotus spp. are outstanding alternatives, since species, such as L. tenuis (Lt) and L. corniculatus (LcT), have high forage quality and are adaptable to different environments. We recently obtained a L. tenuis × L. corniculatus hybrid (LtxLc) with potential new cultivar traits, although its tolerance to flooding stress has not yet been evaluated. In the present study, the performance of LtxLc, its parental diploid accessions, the model legume L. japonicus and tetraploid LcT were evaluated under 55 days of partial submergence stress and a 35‐day recovery period. Physiological, morphological and anatomical traits were analysed, showing that tolerance to partial submergence was positively associated with aerenchyma and adventitious root formation and relative growth rates. Overall, Lt and LtxLc showed the best responses under stress and during the recovery period. Nevertheless, the higher forage value of LtxLc makes it recommendable for use in environments affected by flooding. Our results could be used as breeding criteria for the generation of new cultivars tolerant to partial submergence stress.

Contrasting response of twoLotus corniculatusL. accessions to combined waterlogging-saline stress

“…As a general response, waterlogging stress significantly affected shoot and root dry mass accumulation and net photosynthetic rate in LcT, but did not cause a severe impairment in growth in neither of both accessions. The tolerance extent of L. corniculatus to waterlogging stress was previously described (Antonelli et al, 2019; Striker and Colmer, 2017), and is related with the ability of aerenchyma and adventitious root formation. These traits allow O 2 supply and respiration, sustaining metabolism and growth rates under the hypoxic conditions imposed by the water submergence (Colmer and Voesenek, 2009; McDonald et al, 2002).…”

“…It is worth mentioning that a high variability within individuals of the same population could be an advantage in the search of tolerant traits for forage breeding programs. In fact, the inter-specific hybridization of LcD with other species was already demonstrated to be a useful tool for improving forage legumes (Antonelli et al, 2019; Escaray et al, 2019, 2014).…”

“…Thus, plant responses to waterlogging involve anatomical and morphological changes, such as aerenchyma formation and development of adventitious roots, which aim to increase root oxygenation (Colmer and Voesenek, 2009; McDonald et al, 2002). In particular, in the Lotus genus, aerenchyma formation was shown to correlate with flooding tolerance in several species (Antonelli et al, 2019; revised by Striker and Colmer, 2017).…”

“…In particular, L. corniculatus has been extensively used due to its moderate level of proanthocyanidins (PA), which contributes positively to nutritional quality of ruminant diet, increasing protein fraction assimilation, avoiding cattle bloat and reducing intestinal parasites (Foo et al, 1996; McNabb et al, 1996; Min et al, 2003). Nevertheless, the extended use of commercial cultivars of L. corniculatus (all tetraploids) has failed due to its edaphic requirements and its susceptibility to different stress conditions such as flooding or salinity (Antonelli et al, 2019; Escaray et al, 2019). By contrast, L. tenuis developed a relatively greater tolerance to waterlogging and salinity conditions (revised by Striker and Colmer, 2017), becoming naturalized in the Flooding Pampa.…”

“…This population is diploid and has been used to improve Lotus cultivars through inter-specific hybridization. Although this new germplasm was tested under waterlogging stress (Antonelli et al, 2019) and salinity (Escaray et al, 2019), its stress response under combined waterlogging-saline stress was not yet evaluated. In the present study, we aimed to compare the response to waterlogging, salinity and combined waterlogging-saline stress of the diploid accession of L. corniculatus (described by Escaray et al, 2014) and one of the most common L. corniculatus cultivars used as forage production in South America (L. corniculatus cv.…”