The impact of domestication and crop improvement on arbuscular mycorrhizal symbiosis in cereals: insights from genetics and genomics

Abstract

Contents Summary 1135 I. Introduction 1135 II. Recruitment of plant metabolites and hormones as signals in AM symbiosis 1136 III. Phytohormones are regulators of AM symbiosis and targets of plant breeding 1137 IV. Variation in host response to AM symbiosis 1137 V. Outlook 1137 Acknowledgements 1139 References 1139 SUMMARY: Cereals (rice, maize, wheat, sorghum and the millets) provide over 50% of the world's caloric intake, a value that rises to > 80% in developing countries. Since domestication, cereals have been under artificial selection, largely directed towards higher yield. Throughout this process, cereals have maintained their capacity to interact with arbuscular mycorrhizal (AM) fungi, beneficial symbionts that associate with the roots of most terrestrial plants. It has been hypothesized that the shift from the wild to cultivation, and above all the last c. 50 years of intensive breeding for high-input farming systems, has reduced the capacity of the major cereal crops to gain full benefit from AM interactions. Recent studies have shed further light on the molecular basis of establishment and functioning of AM symbiosis in cereals, providing insight into where the breeding process might have had an impact. Classic phytohormones, targets of artificial selection during the generation of Green Revolution semi-dwarf varieties, have emerged as important regulators of AM symbiosis. Although there is still much to be learnt about the mechanistic basis of variation in symbiotic outcome, these advances are providing an insight into the role of arbuscular mycorrhiza in agronomic systems.

The genetic architecture of host response reveals the importance of arbuscular mycorrhizae to maize cultivation

“…Modern breeding efforts have focused on maximizing yield under homogeneous environments with large quantities of synthetic inputs. It is not clear how the breeding process has impacted the balance of AM symbiosis (discussed in Sawers et al, 2008Sawers et al, , 2018, but major crops do retain the capacity to interact with AMF and they conserve the necessary molecular machinery (e.g. Gutjahr et al, 2008;Nadal et al, 2017).…”

Cross‐scale integration of mycorrhizal function

“…1322–1336) examine plant metabolic plasticity in stressed tomato plants, and note that AM symbioses can help plants deal with this stress, and the Tansley insight by Sawers et al . (; in this issue of New Phytologist , pp. 1135–1140) examines AM symbiosis in light of domestication and crop improvement in cereals.…”

Research Advances of Beneficial Microbiota Associated with Crop Plants

“…Furthermore, a few studies have reported that both artificial management of plant growth environment and conditions, and plant domestication affect the community structure of rhizosphere and endosphere microbiomes [27,119,146,147]. Wild plant species preserve more diversity in associated microbiota for their survival against stress resistance than the domesticated crops.…”