Physiological and biochemical responses to manganese toxicity in ryegrass (Lolium perenne L.) genotypes

Abstract

We studied resistance to manganese (Mn) toxicity under acidic conditions and its relationship with nutrients such as calcium (Ca) and magnesium (Mg) in new perennial ryegrass (Lolium perenne L.) genotypes (One-50, Banquet-II and Halo-AR1) introduced in southern Chile, using the Nui genotype as the reference. Plants were grown in nutrient solution at increased Mn concentrations (0-750 μM) at pH 4.8, and physiological and biochemical features were determined. Under higher Mn concentration, the One-50 genotype had a significantly lower relative growth rate (RGR) of shoots and roots, whereas in the other cultivars this parameter did not change under variable Mn treatments. Increasing the Mn concentration led to an increased Mn concentration in roots and shoots, with Banquet-II and Halo-AR1 having higher Mn in roots than shoots. Shoot Mg and Ca concentrations in all genotypes (except Banquet-II) decreased concomitantly with increasing Mn applications. In contrast to the other genotypes, Banquet-II and Halo-AR1 maintained their net CO assimilation rate regardless of Mn treatment, whereas the chlorophyll concentration decreased in all genotypes with the exception of Banquet-II. In addition, lipid peroxidation in Banquet-II roots increased at 150 μM Mn, but decreased at higher Mn concentrations. This decrease was associated with an increase in antioxidant capacity as well as total phenol concentration. Banquet-II and Halo-AR1 appear to be the most Mn-resistant genotypes based on RGR and CO assimilation rate. In addition, Mn excess provoked a strong decrease in Ca and Mg concentrations in shoots of the Mn-sensitive genotype, whereas only slight variations in the Mn-resistant genotype were noted. When other evaluated parameters were taken into account, we concluded that among the perennial ryegrass genotypes introduced recently into southern Chile Banquet-II appears to be the most Mn-resistant, followed by Halo-AR1, with One-50 being the most sensitive.

Early responses to manganese (Mn) excess and its relation to antioxidant performance and organic acid exudation in barley cultivars

“…We found that Mn content was higher in roots than in shoots, and proportional to increasing Mn treatments in all cultivars. This finding is similar to that reported by Rosas et al, (2007) and Inostroza-Blancheteau et al, (2017) in ryegrass from Chilean Andisol. In contrast, recent studies in maize (Silva et al, 2017) and barley genotypes (Huang et al, 2015) showed that some Mn-tolerant genotypes exhibited higher Mn concentrations in shoots than in roots due to internal tolerance mechanisms.…”

“…whereas Barke and Scalett decreased their biomass parameters, as was reported for Mn-barley sensitive cultivars (Mora et al, 2009;Ribera et al, 2013). Despite previous studies showing that lipid peroxidation (LP) is an important indicator to metal toxicity in ryegrass (Mora et al, 2009;Inostroza-Blancheteau et al, 2017), cucumber (Shi et al, 2005) and maize (Srivastava and Dubey 2011), we observed only an increase of LP in shoot of all cultivars. In contrast, antioxidant performance was given by antioxidant enzymes, where mainly SOD activity was activated.…”

Manganese Stress in Flue-cured Tobacco: Biochemical Responses

“…Previous research indicates that the ability of plant to tolerate Mn toxicity is related to nutrients such as calcium (Ca) and magnesium (Mg), in ryegrass. Magnesium and Ca concentrations in all genotypes decreased concomitantly with increasing Mn applications [7]. Kováčik et al [14] found different plant species have different trends of Mn accumulation; chamomile (Matricaria chamomilia), preferentially accumulated Mn in the roots compared to shoots, but a related species, Tanacetum parthenium, contained more Mn in shoots.…”

“…Planting mainly occurs in paddy soils in which the major preceding crop is rice (Oryza sativa L.) [4]. Long-term flooded cultivation in paddy soils leads to puddling, low pH, and low permeability resulting in excessive soluble Mn 2+ in soil solution [5][6][7]. Plants growing in such paddy soils absorb Mn 2+ to toxic levels [8].…”

Physiology of sensitivity and tolerance of crop plants to high manganese availability in the root environment

“…Horst (1988) considered that crinkle leaf in soybean, cotton (Gossypium hirsutum), and bean may be due to an induced Ca deficiency. High Ca supply in solution alleviates Mn toxicity (Robson and Loneragan 1970) through decreased Mn in plant tissues (Horst and Marschner 1978a;Inostroza-Blancheteau et al 2017). This effect likely results from decreased Mn 2+ activity in solution.…”