The rhizosphere bacterial community of water yam (Dioscorea alata L.) under limited water conditions

Abstract

Introduction

Yam cultivation in West Africa, the largest yam production area, has expanded to the northern Guinea savanna, which receives an annual rainfall of 800–1000 mm. However, variations in rainfall are problematic for the stable productivity of yams. Integrated soil fertility management is urgently needed to improve and stabilise yam productivity. Plants have complex interactions with bacterial communities, influencing their health and environmental adaptability. Although the growth of water yams (Dioscorea alata L.) at various rainfall levels might be related to their interaction with the bacterial community, their structure under water limitation is yet to be elucidated. Here, we evaluated the bacterial community structure in the rhizosphere (Rh) and roots of ‘A-19’ under water limitation conditions.

Materials and Methods

Plants were grown under normal conditions, and watering was reduced to less than 70% for 1 month. Rh and root samples were collected for DNA extraction, and downstream amplicon sequencing analyses were performed.

Results

The dry weight of the shoots, particularly the leaves, decreased under water limitation. Bacterial diversity in the rhizocompartments was significantly reduced. However, bacterial community composition was not affected by water limitation. Despite water-limited conditions, bacterial community structure was robust in the Burkholderia-Caballeronia-Paraburkholderia and Streptomyces clades. These taxa accounted for approximately 60% of the relative abundance in the roots under water limitation.

Conclusion

identifying bacterial community composition of ‘A-19’ under water-limited conditions provides fundamental information for developing integrated soil fertility management strategies across rainfall gradients in West Africa. Our study indicates that ‘A-19’ has a robust bacterial community structure for beneficial interactions with bacteria despite soil water conditions.