Mixed cropping with maize combined with moderate UV-B radiations lead to enhanced flavonoid production and root growth in faba bean

Abstract

Flavonoids have recently been proposed to function as developmental regulators and/or signaling molecules under biotic or abiotic stress. The aim of this study was to determine the composition and concentration of fiavonoid aglycones (kaempferol, luteolin, and quercetin) in faba bean shoots and roots, as affected by interspecific root interactions with maize and moderate UV-B radiation. Independent of the UV-B treatment, interspecific root interactions with maize enhanced the concentration of both quercetin and luteolin in the faba bean shoots and roots by 50 and 97.8%, respectively, and improved the root length by 14.6%. In addition, moderate UV-B radiation facilitated a systematic increase of both aglycones in both shoots and roots without affecting plant growth. To our knowledge, this report is the first work documenting the response of faba bean flavonoids to interspecific root interactions with maize and moderate UV-B radiation, and it provides a new perspective for understanding interspecific interactions.

UV-B Exposure of Black Carrot (Daucus carota ssp. sativus var. atrorubens) Plants Promotes Growth, Accumulation of Anthocyanin, and Phenolic Compounds

“…Such an effect relies on the biosynthesis costs of flavonoids and related phenolic compounds, which are generally higher than those of biomass [36]. Conversely, several authors have reported an increased plant biomass in response to moderate UV-B doses in faba bean [33], radish [37], and Arabidopsis [38]. A similar response was found in our work, where both top and root weights increased upon treatment (Figure 1).…”

“…At the cellular level, UV-B irradiance initially triggers ROS formation, which subsequently increases the biosynthesis of certain phenolic compounds, as part of the non-enzymatic antioxidant defences [26,31,32]. This phenomenon would explain the accumulation of these compounds in non-exposed tissues to UV-B, as observed in maize roots [33]. In fact, low UV-B doses increased the flavonoid content in leaves and roots of nasturtium [34] and kale [35], which indicates that UV-B may act as a systemic inducer of phenolic contents in the whole plant.…”

Intercropping influences component and content change of flavonoids in root exudates and nodulation of Faba bean

“…In our study, the concentrations of flavonol, isoflavone, chalcone and hesperetin in intercropping faba bean root exudates during the nodulation period were increased when compared with monocropping, and we found that flavonol, naringenin and hesperetin of flavonoids in root exudates were more sensitive components relating to faba bean nodulation. Thus, the enhancement of nodulation was likely caused by the enrichment with flavonol, isoflavone, chalcone and hesperetin in root exudates when faba bean was intercropped with wheat, which was similar to the result of Li et al (2012), who found that maize intercropped with faba bean could change the content of quercetin and luteolin that could promote significantly faba bean nodulation. However, legumes nodulation is a complex process which consists of the interaction between legumes root and soil rhizobium, a series of signal transduction and material synthesis, so further investigation is required to evaluate the intrinsic mechanism.…”

“…Flavonoids in root exudates are a class of widely distributed secondary metabolites that play an important function in mediating the interaction of plants with their environment (Pourcel et al 2007). Studies have demonstrated that it is affected by a range of factors, such as crop species, temperature, UV radiation and nitrogen rates (Coronado et al 1995;Zhang & Li 2003;Li et al 2012), and particularly crop species. For instance, the flavonoids in legume root exudates are the inducers of genes responsible for the nodulation process of rhizobium in specific legumes (Broughton et al 2003;Badri & Vivanco 2009;Paul et al 2010;Wang et al 2012).…”

Alleviating the inhibitory effect of salinity stress on nod gene expression in Rhizobium tibeticum – fenugreek (Trigonella foenum graecum) symbiosis by isoflavonoids treatment

“…The inhibitory effects of soil stress may be through affecting the signal exchange process between the two partners (Li et al 2012). According to our knowledge, there is no publication on the effects of signal molecule on the Rhizobium tibeticum Á fenugreek symbiosis under saline conditions.…”