Unlocking the Secrets of Perennial Rice: A Genetic Breakthrough from Chinese Researchers

Rice, the staple food for billions worldwide and a cornerstone of Chinese agriculture, has long been bound by its annual lifecycle—planted, harvested, and replanted each season. This labor-intensive process contributes to soil erosion, high input costs, and environmental strain. However, a groundbreaking discovery by scientists at the Chinese Academy of Sciences (CAS) in Shanghai has identified the genetic key to transforming rice into a perennial crop capable of multiple harvests from a single planting. The Endless Branches and Tillers 1 (EBT1) locus, harboring tandem microRNA156 genes (MIR156B and MIR156C), enables wild rice's remarkable ability to revert from reproductive to vegetative growth, sustaining itself year after year.

This advancement, detailed in a March 19, 2026, Science publication, represents a pivotal moment in plant molecular biology. By resurrecting dormant traits lost during domestication over 10,000 years ago, researchers have engineered rice lines that mimic wild Oryza rufipogon's perennial habit. Field trials in Hainan Province demonstrate plants surviving over two years while producing up to 70 secondary tillers—far surpassing the dozen in conventional varieties—offering a glimpse into sustainable farming's future.

The Evolutionary Journey: From Wild Perennials to Annual Cultivars

Wild rice ancestors like Oryza rufipogon thrive as creeping perennials, propagating clonally through tiller buds that root and form new plants. This grass-like architecture allows continuous growth, with axillary buds reactivating post-flowering to produce fresh shoots every three to four months. Early farmers domesticated these into upright, annual Oryza sativa varieties for compact growth and higher per-season yields, inadvertently selecting against the EBT1 locus. The result: modern rice senesces after seed set, necessitating annual tillage and replanting.

China, producing over 210 million tons of rice annually—about 30% of global output—faces mounting challenges. Labor shortages in rural areas, soil degradation from repeated plowing, and climate variability exacerbate vulnerabilities. Perennial rice addresses these by minimizing disturbance, enhancing soil organic carbon, and reducing erosion, particularly on China's hilly terrains where 60% of farmland lies.

Deciphering EBT1: The Molecular Switch for Plant Longevity

The EBT1 locus on chromosome 1 encodes tandem MIR156B/C genes, master regulators of developmental timing via the age pathway. MicroRNAs (miRNAs) are small non-coding RNAs that silence target genes; miR156 specifically represses SPL (SQUAMOSA PROMOTER BINDING PROTEIN-LIKE) transcription factors, delaying flowering and promoting juvenility. In wild rice, epigenetic modifications—elevated chromatin accessibility and reduced repressive H3K27me3 histone marks—reset MIR156 expression in tiller buds post-flowering. This 'rejuvenation' triggers floral reversion: buds shift back to vegetative proliferation, bypassing senescence.

Researchers used single-segment substitution lines (SSSLs) from wild-cultivated crosses to map EBT1. ATAC-seq (Assay for Transposase-Accessible Chromatin sequencing) and CUT&Tag confirmed wild alleles' open chromatin states. Knocking in the wild EBT1^W1943 allele into cultivated rice restored resetting, yielding vigorous tillering without compromising primary yield potential.

Engineering Perennial Rice: Combining Genes for Robust Traits

To fully recapitulate wild perenniality, the team introgressed EBT1 with PROG1 (PROSTRATE GROWTH 1) and TIG1 (TILLER ANGLE INCREASED 1), genes promoting prostrate architecture and tiller spreading from wild rice. Recombinant lines exhibited grass-like habits: extensive rooting, clonal propagation, and multi-year survival. In Hainan fields, these plants thrived sans replanting, with observations ongoing beyond two years.

Lead researcher Han Bin notes, "By introducing EBT1 into high-yield cultivated rice, we created perennial 'wild-like rice' that has endured over two years." While secondary tillers currently yield sterile flowers, this proof-of-concept opens doors to fertility restoration via further breeding.

Building on Yunnan University's PR23 Legacy

This discovery complements prior innovations like PR23, developed by Professor Hu Fengyi at Yunnan University since 2009. Released in 2018, PR23—bred via interspecific hybridization—allows 6-8 harvests over 4 years, cutting costs by 50% (from labor, seeds, tillage), boosting soil nitrogen by 20%, and sequestering carbon. By 2022, over 18,000 hectares in Yunnan adopted it, with yields matching annual elites (7-9 tons/ha). The EBT1 work provides precise genetic tools to enhance PR23-like varieties, targeting sterility and regional adaptation.

Photo by Pontus Wellgraf on Unsplash

Agronomic and Economic Benefits for Chinese Farmers

Perennial rice slashes production costs: no annual seeding (20-30% savings), reduced tillage (less fuel, machinery wear), and lower herbicide needs due to competitive tillering. In Yunnan trials, PR23 netted 30-50% higher profits over multi-seasons. For China, with 30 million hectares under rice, scaling could save billions in inputs amid rural aging (average farmer age 57). Ideal for marginal lands—slopes, uplands—where machinery falters, it bolsters food security for 1.4 billion.Read the full study here.

• Cost reduction: 50%+ from year 2
• Yield stability: Comparable to annuals over cycles
• Labor savings: One planting, multiple harvests

Environmental Impacts: Soil Health and Climate Resilience

Annual tillage releases 1-2 tons CO2e/ha yearly; perennials halve emissions via no-till, enhancing soil organic matter (up 15-20% in PR23 fields). Deeper roots improve water retention (20-30% more), drought tolerance, and nutrient cycling, cutting fertilizer by 20-40%. In erosion-prone southern China, roots stabilize slopes, reducing sediment runoff by 60%. Globally, perennial grains could mitigate agriculture's 24% GHG footprint.China Daily coverage.

Challenges and the Path Forward

Key hurdles: secondary tiller fertility (sterile now), pathogen buildup over years, and adaptation to diverse ecologies. Breeders must pyramid more loci (rhizome formation, seed set). Regulatory approval for GM traits (if used) and farmer training are essential. Collaborations between CAS, Yunnan University, and international partners like The Land Institute accelerate progress.

Implications for Global Cereal Crops and Food Security

EBT1/miR156 mechanisms may apply to wheat, maize—miR156 mutants like Corngrass1 confer perenniality. For China, exporting tech to Africa (e.g., Uganda trials) aids Belt and Road. Projections: 10-20% adoption could offset climate losses (5-10% yield drop by 2050).

Role of Chinese Higher Education in Agrobiotech Innovation

CAS Shanghai Center exemplifies China's fusion of academia and research, training PhDs in genomics. Yunnan University's PR23 stemmed from Hu Fengyi's lab, producing alumni leading sustainable ag programs. Rising demand for plant geneticists offers careers in breeding, with salaries 150k-300k RMB/year. Programs at China Agricultural University, Huazhong Ag University equip students for this frontier.Xinhua report.

Photo by Raymond Tan on Unsplash

Future Outlook: Toward Commercial Perennial Varieties

With EBT1 toolkit, hybrid perennial elites could debut by 2030, targeting 1 million ha. Policy support via China's 14th Five-Year Plan boosts funding. This convergence of epigenetics, breeding, and sustainability heralds a greener rice revolution.