Carletti Giorgia, Fricano Agostino, Mazzucotelli Elisabetta, Cattivelli Luigi
Council for Agricultural Research and Economics, Research Centre for Genomics and Bioinformatics, Via San Protaso 69, Fiorenzuola d' Arda (PC), 29017, Italy.
Plant Methods. 2025 Jul 9;21(1):93. doi: 10.1186/s13007-025-01408-2.
Soil compaction is defined as the reduction of air-filled pore space affecting soil density, water conductivity and nutrient availability. These conditions negatively influence root morphology, root development and plant growth leading to yield loss. To date, the ability of roots to penetrate compacted soil has been investigated using high density agar or wax-petrolatum layers as a proxy for compaction. Nevertheless, these methods are not realistic and fail to account for the root-soil interaction that influences root growth ability.
Artificially compacted soil lumps were prepared using natural field soil mixed with sand and vermiculite in a 1:1:0.2 ratio and adjusted to a final water content of 31%. A Genome Wide Association Study (GWAS) was performed to validate this new methodology, combining a panel of 139 barley cultivars with a Single Nucleotide Polymorphism (SNP) dataset of 5,317 polymorphic markers. The panel was evaluated at seedling stage for four traits: total root length, average of diameter width, seminal root number, shoot: root weight ratio and two novel Quantitative Trait Loci (QTLs) associated with total root length were identified on Chr 4 H and 5 H. Four genes (a Nitrate Transporter1 (NRT1)/Peptide Transporter (PTR) family protein 2.2, a Hedgehog-interacting-like protein, an expansin and a cyclic nucleotide-gated channel) were hypothesized as plausible candidates for further investigation, given their implication in root development. In addition, the new phenotyping method revealed an altered plagiogravitropism phenomenon in barley during root emergence in compact substrates. In uncompacted soil, only the primary root exhibits vertical gravitropic set-point angle while a variable number of embryonic seminal roots develop with a shallower growth angle. In contrast, in compacted substrate all roots developed vertically to restore the growth angle after reaching a length of 4-5 millimetres.
A methodology based on root-soil interaction is presented as a new method for root growth evaluation and genomic studies in seedlings growing in compacted soil.
土壤压实被定义为影响土壤密度、导水性和养分有效性的充满空气的孔隙空间的减少。这些状况对根系形态、根系发育和植物生长产生负面影响，导致产量损失。迄今为止，人们使用高密度琼脂或蜡 - 凡士林层作为压实的替代物来研究根系穿透压实土壤的能力。然而，这些方法并不现实，且未能考虑影响根系生长能力的根 - 土相互作用。
使用天然田间土壤与沙子和蛭石按1:1:0.2的比例混合制备人工压实的土块，并将其最终含水量调整为31%。进行了全基因组关联研究（GWAS）以验证这种新方法，该研究将一组139个大麦品种与一个包含5317个多态性标记的单核苷酸多态性（SNP）数据集相结合。在幼苗期对该组品种的四个性状进行了评估：总根长、平均直径宽度、种子根数、地上部：根重比，并且在4H和5H染色体上鉴定出了两个与总根长相关的新的数量性状位点（QTL）。鉴于四个基因（一个硝酸盐转运蛋白1（NRT1）/肽转运蛋白（PTR）家族蛋白2.2、一个刺猬相互作用样蛋白、一个扩张蛋白和一个环核苷酸门控通道）与根系发育有关，它们被假定为进一步研究的可能候选基因。此外，这种新的表型分析方法揭示了大麦在紧实基质中根系萌发期间斜向重力性现象的改变。在未压实的土壤中，只有初生根表现出垂直重力性设定点角度，而数量不等的胚性种子根以较浅的生长角度发育。相比之下，在压实的基质中，所有根系在达到4 - 5毫米长度后垂直生长以恢复生长角度。
提出了一种基于根 - 土相互作用的方法，作为评估紧实土壤中幼苗根系生长和进行基因组研究的新方法。
