Flint maize root mycorrhization and organic acid exudates under phosphorus deficiency: Trends in breeding lines and doubled haploid lines from landraces

Abstract

Aims: High maize yields in modern well‐managed agroecosystems depend on the use of elite varieties and hybrids. Unfortunately, because of repeated selection at high fertilizer rates, some beneficial traits, such as the interaction with arbuscular mycorrhizal fungi or the release of organic acid anions for phosphate mobilization and for attracting beneficial microorganisms, might be gradually declining in modern elite genotypes. However, old founder lines and landraces possibly carry genetic relicts that originate from pre‐green revolution times that are useful for breeding elite material for low input farming systems. Methods: Seedling colonization with arbuscular mycorrhizal fungi (AMF) and organic acid anion release were measured in flint lines that were released over more than five decades ago and in six preselected doubled haploid (DH) lines from landraces. P‐uptake‐related root traits were compared under P‐sufficient and P‐deficient conditions. Results: Weak trends for the loss of AMF colonization or changes in organic acid anion release at low P supply were detected in modern varieties. One DH line from a landrace was found with increased mycorrhization, whereas others were similar to modern elite lines. Overall, substantial genetic variance was encountered for these traits. Conclusions: The concern that modern elite maize varieties have lost beneficial traits for nutrient acquisition is not substantiated for the flint pool of maize, although weak trends exist. Lines associated with better P‐acquisition efficiency under limited P availability should be utilized for breeding more sustainable varieties.

A Metagenomic and Gene Expression Analysis in Wheat (T. durum) and Maize (Z. mays) Biofertilized with PGPM and Biochar

“…Moreover, the results obtained may be influenced by the properties of the microorganisms in the consortia such as the biological nitrogen fixation, synthesis of phytohormones (IAA, GA3, and cytokinin), and increased availability of micro- and macronutrients (phosphorus and iron) [ 54 ]. All data reported were consistent with the literature [ 2 , 31 , 53 , 55 , 56 , 57 ], that is, the presence of MC in combination with AMF determined an increase in root development, nutrient uptake, and root and shoot biomass. The novelty here is that the results were obtained using a new technology of functionalization and delivery with biochar and in two “in lab”-designed microbial consortia [ 40 ], which were not tested previously on wheat ( T. durum ) and maize ( Z. mays ).…”

“…Moreover, the agricultural sector is strongly interested in making the cultivation of commodities such as maize and wheat more sustainable because of their relevance to human and animal nutrition, but this will need important changes in fertilization and energy consumption to avoid the production of pollutants [ 22 , 23 ]. Previous studies have evaluated the field application of mycorrhizae to maize [ 24 ] and wheat [ 25 , 26 , 27 ], obtaining promising results, as their application increased the root absorption of micronutrients from the soil [ 28 , 29 , 30 , 31 ]. Other studies have shown that the application of biofertilizers to wheat cultivation is hampered by the variability in plant responses and environmental conditions [ 32 , 33 ].…”

Decline of seedling phosphorus use efficiency in the heterotic pool of flint maize breeding lines since the onset of hybrid breeding

“…The weak Root/Shoot and RootDiam correlation and that with several other traits that were different in LP and HP, potentially indicates a trade‐off for acclimation to contrasting P conditions, as the increased contribution of one trait resulted in the decreased contribution of another trait (Table 2). The negative trend for PUE in juvenile flints was corroborated in another soil (Li et al., 2021), but as only young roots were considered here, field trials with the investigated genotypes are required to confirm the importance of juvenile PUE traits for adult plants and for final grain yield and grain PUE. Such experiments should also consider other traits that are important for P efficiency in adult plants, such as the presence of cortical root aerenchyma (Postma & Lynch, 2011) or the association with mycorrhiza (Li et al., 2021).…”

“…The negative trend for PUE in juvenile flints was corroborated in another soil (Li et al., 2021), but as only young roots were considered here, field trials with the investigated genotypes are required to confirm the importance of juvenile PUE traits for adult plants and for final grain yield and grain PUE. Such experiments should also consider other traits that are important for P efficiency in adult plants, such as the presence of cortical root aerenchyma (Postma & Lynch, 2011) or the association with mycorrhiza (Li et al., 2021).…”

Mechanistic assessment of tolerance to iron deficiency mediated by Trichoderma harzianum in soybean roots

“…However, it is unknown whether the increased citrate and malate accumulation in the roots occurred as a result of the plant's response to TH or whether TH was capable of releasing these acids to mobilize Fe. Mycorrhizal fungi, particularly AMF, have been shown to release significant amounts of organic acids in response to phosphorus deficiency in plants (Andrino et al, 2021 ; Li et al, 2021 ). Further research is required to determine how TH promotes the production of organic acids in plants that aid in the acquisition of Fe.…”