Effect of Root Colonization by Arbuscular Mycorrhizal Fungi on Growth, Productivity and Blast Resistance in Rice

Abstract

Background: Arbuscular mycorrhizal (AM) fungi form symbiotic associations with roots in most land plants. AM symbiosis provides benefits to host plants by improving nutrition and fitness. AM symbiosis has also been associated with increased resistance to pathogen infection in several plant species. In rice, the effects of AM symbiosis is less studied, probably because rice is mostly cultivated in wetland areas, and plants in such ecosystems have traditionally been considered as non-mycorrhizal. In this study, we investigated the effect of AM inoculation on performance of elite rice cultivars (Oryza sativa, japonica subspecies) under greenhouse and field conditions, focusing on growth, resistance to the rice blast fungus Magnaporthe oryzae and productivity. Results: The response to inoculation with either Funneliformis mosseae or Rhizophagus irregularis was evaluated in a panel of 12 rice cultivars. Root colonization was confirmed in all rice varieties. Under controlled greenhouse conditions, R. irregularis showed higher levels of root colonization than F. mosseae. Compared to non-inoculated plants, the AM-inoculated plants had higher Pi content in leaves. Varietal differences were observed in the growth response of rice cultivars to inoculation with an AM fungus, which were also dependent on the identity of the fungus. Thus, positive, negligible, and negative responses to AM inoculation were observed among rice varieties. Inoculation with F. mosseae or R. irregularis also conferred protection to the rice blast fungus, but the level of mycorrhiza-induced blast resistance varied among host genotypes. Rice seedlings (Loto and Gines varieties) were pre-inoculated with R. irregularis, transplanted into flooded fields, and grown until maturity. A significant increase in grain yield was observed in mycorrhizal plants compared with non-mycorrhizal plants, which was related to an increase in the number of panicles. Conclusion: Results here presented support that rice plants benefit from the AM symbiosis while illustrating the potential of using AM fungi to improve productivity and blast resistance in cultivated rice. Differences observed in the mycorrhizal responsiveness among the different rice cultivars in terms of growth promotion and blast resistance indicate that evaluation of benefits received by the AM symbiosis needs to be carefully evaluated on a case-by-case basis for efficient exploitation of AM fungi in rice cultivation.

Effects of Mycorrhizal Colonization on Transcriptional Expression of the Responsive Factor JERF3 and Stress-Responsive Genes in Banana Plantlets in Response to Combined Biotic and Abiotic Stresses

“…Various defense mechanisms have been discussed in this concern including cell wall lignification, the accumulation of polyphenolic compounds and defensive proteins, and the activation of antioxidant and pathogenesis-related enzymes (Abdel-Fattah et al, 2011;Rashad et al, 2020a). In addition, the growth-promoting and nutrient uptake enhancing effects to ameliorate the adverse influences of the infection have also been reported (Campo et al, 2020;Rashad et al, 2020b). On the other hand, the mycorrhizal colonization of the banana plantlets alleviated the adverse effects due to salinity stress.…”

Mycorrhiza-Induced Resistance against Foliar Pathogens Is Uncoupled of Nutritional Effects under Different Light Intensities

“…In fact, AM enhances plant phenotypic plasticity, an important advantage in heterogeneous and changing environments where the precise allocation of limited resources between growth and stress resistance is critical for survival [15][16][17]. Mycorrhizal plants are usually more resistant to abiotic stresses such as drought, salinity, and heavy metal pollution [17][18][19], but AMF can also increase plant resistance/tolerance to biotic stresses by triggering the so-called mycorrhiza-induced resistance (MIR) against diverse root and foliar pathogens and pests [20][21][22][23][24][25][26][27][28]. In return, AMF require photosynthates and lipids from the plant to complete their life cycle.…”

Effect of in vitro Produced Arbuscular Mycorrhizal Fungi Inoculum on Anaerobic Direct Seeded and Transplanted Paddy

“…In a field study, Watanarojanaporn et al (2013) reported that rice plants harvested from the Systemic Rice Intensification (SRI) managed plots showed significantly higher total biomass, root dry weight, and grain filling than those obtained from conventional flooded, direct seeded paddy. Rice seedlings of European cultivars such as Loto and Gines varieties, when pre-inoculated with AM fungi R. irregularis, transplanted into flooded fields, and grown until maturity, showed significant increase in grain yield in mycorrhiza inoculated plants compared with non-mycorrhizal plants, wherein the yield increase was attributed to increase in the number of panicles (Campo et al, 2020). Consistent with the earlier studies, our study reconfirms the above findings that AMF could be potentially used in anaerobic paddy cultivation, both for direct seeded and transplanted paddy.…”