The nematophagous root endophyte Pochonia chlamydosporia enhances tolerance to drought in soybean

Climate changes have led to fluctuations in rainfall, reducing crop productivity during drought conditions. In addition to developing tolerant genotypes, plant growth-promoting microorganisms could be applied to maintain sustainable agriculture under environmental stresses.

Therefore, in this study the ability of the nematophagous fungus P. chlamydosporia to promote drought tolerance in soybean plants was assessed.

Under water deficit conditions, the inoculated plants exhibited a one-day delay in reaching the same water potential as the noninoculated plants. Fungal colonization improved physiological parameters associated with drought tolerance, resulting in a 2- to 5-fold increase in water use efficiency (A/E). Moreover, the behavior of the inoculated drought-sensitive BR16 plants resembled that of the drought-tolerant parental Embrapa 48. The relative water content (RWC) increased from 15% to 26% in the leaves and roots of inoculated plants of both genotypes under water deficit. Consequently, the intrinsic efficiency of water use (A/gs) was 6.7-fold greater in the inoculated BR 16 plants under water deficit. The increase in drought tolerance may be related to the induction of root growth in inoculated plants, although this increase was not associated with hydraulic conductivity. Similarly, fungal inoculation led to increased concentrations of phenolics, which directly or indirectly contributed to drought tolerance. Reduced concentrations of proline and ABA confirmed that P. chlamydosporia alleviated water deficit stress. Conversely, the increases in spermine and spermidine concentrations may act as osmoprotectants, relieving the water deficit in the roots.

Thus, P. chlamydosporia inoculation may contribute to maintaining soybean productivity during periods of limited water availability.