Tomato plants delay shoot meristem maturation to achieve heat-stress resilience

As global temperatures continue to rise, extreme heatwaves pose a significant threat to agricultural productivity. Studies estimate that for every 1°C increase above pre-industrial levels, crop yields decline by approximately 6-8%. The ability of plants to withstand heat stress is therefore critical for ensuring food security, yet the underlying molecular mechanisms have largely remained elusive.

Now, however, a new study led by Prof. XU Cao's team at the Institute of Genetics and Developmental Biology (IGDB) of the Chinese Academy of Sciences sheds light on an adaptive strategy that may be pivotal in developing heat-resilient crop varieties amid escalating climate change. Specifically, the study reveals a novel mechanism by which tomato plants actively mitigate heat stress and stabilize yield through the developmental reprogramming of shoot apical stem cells.

The research was published in Developmental Cell on April 2.

Stem cells in the shoot apical meristem (SAM) are essential for aerial morphogenesis—the process by which plants develop above-ground structures—and directly influence crop yield. However, heat stress can cause abnormal differentiation or even necrosis of these stem cells, resulting in developmental defects, plant mortality, and significant yield losses. Understanding how SAM stem cells adapt to heat stress is therefore critical for advancing cultivation techniques and breeding more resilient crop varieties.

In their study, Prof. XU Cao and his team identified a key molecular adaptation mechanism in tomato plants. Under heat stress, reactive oxygen species (ROS) accumulate and promote the phase separation of TERMINATING FLOWER (TMF), a floral repressor. This modification prolongs the transcriptional repression of floral identity genes by TMF condensates, effectively reprogramming SAM development. By delaying shoot maturation, the plant extends vegetative growth, allowing it to avoid premature reproductive transitions under unfavorable conditions.

During early vegetative growth, tomato plants can enter a dormancy-like state in response to heat stress, temporarily suspending their maturation program. Once temperatures normalize, development resumes, ensuring stable yields. This strategic suspension has been shown to prevent 34–63% of yield losses in the first fruit truss, highlighting its significant role in heat resilience.

The study proposes that this redox-controlled bet-hedging mechanism functions as a survival strategy for sessile plants, enabling them to delay flowering during adverse conditions while ensuring reproductive success once environmental stresses subside.

The researchers emphasized that this discovery provides a new conceptual framework for developing climate-smart crops with environmentally responsive yield stability. The mechanistic insights identified in this study could guide precision breeding efforts aimed at improving agricultural productivity in a changing climate.

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