One maize gene switch trades heat tolerance for better leaf shape
Wang J, Xie Y, An X, Wen Y, Chu Z
Crop Improvement
The corn towering in fields near you could soon be bred to stand more upright for tighter rows, but this research shows that same upgrade might make it wilt faster in a heat wave.
Corn plants have a tiny genetic dial called ZmMIR319A that controls two things at once: how much their leaves flare out, and how well they cope with heat stress. When this dial turns down leaf angle to let plants grow more upright and packed together, it also turns down the plant's heat defenses, so breeders get better yields from dense planting but a corn that struggles more in a heatwave. Turns out you can't easily get both traits maxed out at the same time.
Key Findings
ZmMIR319A represses ZmTCP5/ZmTCP44 transcription factors, which normally block auxin transporter genes ZmPIN1 and ZmPIN8, so the microRNA's activity reduces leaf angle by boosting cell growth in the leaf's ligular region
Under heat stress, ZmMIR319A levels drop quickly, allowing ZmTCP5/44 to accumulate and suppress heat shock protein genes ZmHSP70-4 and ZmHSP90-5, weakening thermotolerance
ZmMIR319A knockout maize showed increased grain yield under high-density planting but reduced heat tolerance, demonstrating a direct architecture-versus-stress-resilience tradeoff
chevron_right Technical Summary
Scientists found a single genetic switch in maize that controls both how upright its leaves grow and how well it survives heat waves, but improving one trait comes at the cost of the other. This discovery could help breeders design corn plants suited for tighter planting and a warming climate, as long as they manage the tradeoff.
Abstract Preview
Original paper
The ZmMIR319A-ZmTCP5/44 module bifurcates into two pathways to coordinately regulate leaf angle and thermotolerance in maize.
Global warming increasingly threatens crop productivity, necessitating new varieties that combine high yield potential with climate resilience. Optimizing plant architecture, particularly by reduci...
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Maize, also known as corn in North American English, is a tall stout grass that produces cereal grain. The leafy stalk of the plant gives rise to male inflorescences or tassels which produce pollen, and female inflorescences called ears. The ears yield grain, known as kernels or seeds. In modern ...