Diversity of Trigonella foenum graecum Microsymbionts in Morocco

Abstract

Trigonella foenum graecum is a medicinal and culinary plant with varied health benefits. The improvement of its growth in weak soils depends on symbiotic soil bacteria called rhizobia which contribute to the autonomy of legumes towards nitrogen. In this work, we characterized 75 bacteria isolated from root nodules of Fenugreek grown in different soils of the Eastern Morocco with the aim to select some performant strains to use as inoculum for the improvement of the plant growth and yield in weak soils of Moroccan semi-arid areas. We found a great phenotypic diversity of fenugreek rhizobia and they were more tolerant to environmental stresses than the reference strains. The strain S3D has similar behavior as Ensifer meliloti strain USDA1002, whereas the other strains analyzed were different from the studied reference strains. There was no relationship between rep-PCR fingerprinting and phenotypic properties. The nearly 16S rRNA gene sequence of some representative strains showed they are closely related to the genus Ensifer with the highest similitude values (100%) with E. meliloti USDA1021. Sequencing of the symbiotic nodC gene from some representative strains revealed they were close to nodC sequences of different Ensifer meliloti strains. Host range tests revealed that all the fenugreek rhizobia nodulated several legumes from different Fabaceae tribes. In conclusion, the strains analyzed are very infective and may be used as inoculum in the arid areas of Morocco.