In autumn-sown barley fields across central and eastern China, a few days can decide whether farmers have time to plant rice after the spring harvest. Researchers have identified a pairing of barley gene variants that helps plants mature earlier without reducing grain yield under the field conditions they studied.
The timing matters because farmers in these regions often grow two crops on the same land in one year. Barley is planted in autumn and harvested in late spring, making room for a summer crop such as rice. If barley takes too long to mature, it can disrupt that schedule. An earlier harvest can also help barley avoid heat and rain late in its growing season.
A team led by Ping Yang of the Chinese Academy of Agricultural Sciences worked with researchers at the IPK Leibniz Institute to investigate how Chinese barley adapted to this system. They studied 505 Chinese barley varieties and 27 introduced reference lines, combining field trials and genetic research with historical records covering eight decades. Their analysis traced changes in the genetic makeup of Chinese barley since the 1940s.
The researchers found that a variant of the PHYTOCHROME C, or PhyC, gene can speed up the emergence of barley ears and the plant’s maturity. The change alters one amino acid, a building block of proteins. The variant appears to have come from East Asian barley and spread through modern breeding.
But the PhyC variant does not work the same way with every partner gene. Paired with a version of the flowering regulator VRN1 common in spring barley, it can lower plant biomass and harm traits linked to yield. With a VRN1 version typical of winter barley, which helps plants respond to long periods of cold, the early-maturing PhyC variant brought earlier development without a grain-yield loss in the conditions tested.
The two genes sit close together on the same chromosome, so they can be inherited as a pair. Their combination became more common in Chinese autumn-sown barley varieties from the 1960s onward. Since the 1990s, it has appeared in more than 60% of the modern autumn-sown varieties examined.
The team also used base editing, a precise method for changing individual DNA building blocks, to recreate the PhyC change. Tests confirmed that it led to earlier development in barley and wheat. In rice, the same change delayed flowering instead. Barley and wheat respond to longer days, while rice responds to shorter days, which may explain the difference.
The findings, published in Nature, show why a gene’s partners and the crop’s biology matter when breeders seek earlier harvests. The results point to a possible way to fit barley more reliably into double-cropping schedules, but they do not yet show how the gene pairing will perform everywhere. Further field trials are needed to test it in other varieties and growing regions.