Microbial Diversity of Upland Rice Roots and Their Influence on Rice Growth and Drought Tolerance

Abstract

Among abiotic stresses, drought is one of the most important factors limiting plant growth. To increase their drought tolerance and survival, most plants interact directly with a variety of microbes. Upland rice (Oryza sativa L.) is a rice ecotype that differs from irrigated ecotype rice; it is adapted to both drought-stress and aerobic conditions. However, its root microbial resources have not been explored. We isolated bacteria and fungi from roots of upland rice in Xishuangbanna, China. Four hundred sixty-two endophytic and rhizospheric isolates (337 bacteria and 125 fungi) were distributed. They were distributed among 43 genera on the basis of 16S rRNA and internal transcribed spacer (ITS) gene sequence analysis. Notably, these root microbes differed from irrigated rice root microbes in irrigated environments; for example, members of the Firmicutes phylum were enriched (by 28.54%) in the roots of the upland plants. The plant growth-promoting (PGP) potential of 217 isolates was investigated in vitro. The PGP ability of 17 endophytic and 10 rhizospheric isolates from upland rice roots was evaluated under well-irrigated and drought-stress conditions, and 9 fungal strains increased rice seedling shoot length, shoot and root fresh weight (FW), antioxidant capability, and proline (Pro) and soluble sugar contents. Our work suggests that fungi from upland rice roots can increase plant growth under irrigated and drought-stress conditions and can serve as effective microbial resources for sustainable agricultural production in arid regions.

The influence of endophytes on rice fitness under environmental stresses

“…Streptomyces mutabilis also improves rice root architecture under drought conditions, which is attributed to its ACCD-and phosphatase-producing ability (Suralta et al 2018). Other studies have also reported similar effect of ACCD-producing microbes (Arunthavasu et al 2019;Pang et al 2020;Kumar et al 2021). Engineering endophytes or other PGP microbes for ACCD enzymatic activity therefore represents a way forward to ultimately boost rice production.…”

Relationship between Plant Roots, Rhizosphere Microorganisms, and Nitrogen and Its Special Focus on Rice

“…The process of lowland rice ecotype from paddy field to upland can be specifically enriched by some Gram-positive microbes, such as thermoleophilia and actinobacteria [139]. Upon further isolation and screening of root system functional microorganisms in upland rice, it was found that root microbes in upland rice could promote plant growth under drought and irrigation conditions, and may be an effective microbial resource to promote crop growth and drought tolerance [140]. The formation of paddy-upland rotation alleviates the internal environment and soil fertility accumulation, which makes the paddy field more resistant to external environmental disturbance than the dry farming ecosystem [141].…”

Bioprospecting of Rhizosphere-Resident Fungi: Their Role and Importance in Sustainable Agriculture

“…Presently, most of the research studies are focused on combating plant diseases through chemical insecticides or pesticides and fungicides, which are lethal to beneficial soil microflora and are also not safe for human consumption. Moreover, many chemical fertilizers, chiefly N, P, and K, have been applied to improve various crop plants’ growth, which causes soil pollution [ 240 ]. Therefore, different eco-friendly strategies have been put forth by research communities in the last decade to minimize the use of chemical-based fertilizers in crop improvement and management studies.…”