Microbial interactions and traits to improve quinoa resilience to climate variability

Abstract

Quinoa (Chenopodium quinoa Willd.) is an Andean crop with exceptional adaptation to harsh environments, yet drought remains a major constraint to stable production in the Bolivian Altiplano. Beneficial microorganisms represent a promising strategy to enhance crop resilience, but knowledge of native quinoa microbiomes, drought-adapted plant growth-promoting rhizobacteria (PGPR), and effective bioinoculant technologies remains limited. This thesis investigated the role of native microorganisms in quinoa drought tolerance and developed microbial technologies for sustainable production in the Bolivian Altiplano. The work combined microbiome analyses, culture-dependent bacterial isolation, greenhouse and field experiments, and bioinoculant formulation. Root microbiome analyses showed that quinoa genotype strongly influenced endophytic bacterial community assembly, while drought primarily altered the microbiome of the drought-susceptible genotype. In contrast, the drought-tolerant genotype maintained a stable root microbiome, suggesting that microbiome resilience contributes to drought adaptation. Culture-dependent screening identified several drought-tolerant PGPR with plant growth-promoting traits. Among these, strains of Serratia, Pseudomonas, and Bacillus consistently enhanced quinoa growth under drought. For practical application, low-cost production strategies were developed using brewery spent yeast as a culture medium and carrageenan bio-beads as bacterial carriers. Optimised bio-beads maintained bacterial viability and enabled successful field application. In field trials, Serratia sp. IIFB006 significantly increased quinoa growth and yield under Altiplano conditions. Quinoa genotypes also differed markedly in their response to Pseudomonas sp. inoculation, demonstrating that host genotype is a key determinant of PGPR effectiveness. Overall, integrating native drought-adapted microorganisms, sustainable formulation technologies, and host genotype selection provides a promising strategy for climate-resilient quinoa production. These findings advance the understanding of plant–microbiome interactions under drought and support the development of microbial bioinoculants for resource-limited agriculture.