Self-alleviation of continuous cropping obstacles in potato via root exudate-driven recruitment of growth-promoting bacteria

Continuous cropping (CC) obstacles are among the primary factors limiting the development of global agriculture. Although most plants are negatively affected by barriers that develop with CC, they may also overcome obstacles by altering the soil biological and chemical environment to favor plant growth. In this study, we investigated the mechanism by which plants recruit beneficial microorganisms using root exudates to alleviate obstacles in a 10- year CC potato system. On day 20 after potato emergence in a CC system, soil microorganisms promoted an increase in adventitious root (AR) numbers by increasing indole-3-acetic acid (IAA) content in rhizosphere soil. Analysis of rhizosphere bacterial communities using 16S rRNA sequencing revealed that CC altered community structure, with increased abundance of Pantoea sp. MCC16. Irrigation with root exudates from CC potato significantly increased AR numbers and Pantoea sp. MCC16 abundance. According to untargeted metabolomic analysis, nobiletin was identified as promoting Pantoea sp. MCC16 colonization in the rhizosphere. Last, application of nobiletin or Pantoea sp. MCC16 significantly increased the yield of CC potatoes. Thus, CC plants can actively secrete unique metabolites nobiletin to recruit Pantoea sp. MCC16, a high IAA producer, to help plants recover functional traits and mitigate CC obstacles.