Heterogeneity of the rice microbial community of the Chinese centuries-old Honghe Hani rice terraces system.

Pascal Alonso,Christian Vernière,Pierre Gladieux,Eric Desmarais,Romain Ferdinand,Philippe Roumagnac,Frédéric Mahé,Darren P Martin,Denis Filloux,Jean‐Benoit Morel,Hervé Sanguin,Frédérique Cerqueira,Xiahong He,Huichuan Huang,Baihui Jin,Laurence Blondin

doi:10.1111/1462-2920.15114

Abstract

SummaryThe Honghe Hani rice terraces system (HHRTS) is a traditional rice cultivation system where Hani people cultivate remarkably diverse rice varieties. Recent introductions of modern rice varieties to the HHRTS have significantly increased the severity of rice diseases within the terraces. Here, we determine the impacts of these recent introductions on the composition of the rice‐associated microbial communities. We confirm that the HHRTS contains a range of both traditional HHRTS landraces and introduced modern rice varieties and find differences between the microbial communities of these two groups. However, this introduction of modern rice varieties has not strongly impacted the overall diversity of the HHRTS rice microbial community. Furthermore, we find that the rice varieties (i.e. groups of closely related genotypes) have significantly structured the rice microbial community composition (accounting for 15%–22% of the variance) and that the core microbial community of HHRTS rice plants represents less than 3.3% of all the microbial taxa identified. Collectively, our study suggests a highly diverse HHRTS rice holobiont (host with its associated microbes) where the diversity of rice hosts mirrors the diversity of their microbial communities. Further studies will be needed to better determine how such changes might impact the sustainability of the HHRTS.

Highlights

During and since the Green Revolution, governments and agricultural stakeholders all around the world have promoted the widespread introduction to cropping systems of modern high-yielding crop varieties
Have significantly structured the rice microbial community composition and that the core microbial community of Honghe Hani rice terraces system (HHRTS) rice plants represents less than 3.3% of all the microbial taxa identified
Both landraces and modern rice varieties are grown in the Malizhai HHRTS

Summary

Introduction

During and since the Green Revolution, governments and agricultural stakeholders all around the world have promoted the widespread introduction to cropping systems of modern high-yielding crop varieties. There are a number of Globally Important Agricultural Heritage Systems (GIAHS) within which landraces (traditional varieties) are still cultivated (FAO, http://www.fao.org/ giahs/en/) Many of these GIAHSs were left largely unchanged by the Green Revolution, some, such as the Honghe Hani rice terraces system (HHRTS), have more recently experienced both the introduction of modern highyielding rice varieties and an increase in chemical usage (Yang et al, 2017; Dedeurwaerdere and Hannachi, 2019). Hundreds of years of rice varietal selection within the HHRTS has yielded at least 195 local rice landraces (Oryza sativa) and 47 wild rice landraces (Oryza rufipogon and Oryza nivara) (Jiao et al, 2012) These diverse rice landraces are grown by each Hani household in complex heterogeneous mosaics, in narrow paddy fields averaging 150 m2 within each of which only one rice landrace is cultivated

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