Scientists discover gene that causes apple trees to grow downwards

Plant geneticists have made a groundbreaking discovery regarding the “weeping” architecture in apple trees, where branches grow downwards. This finding has the potential to significantly enhance orchard fruit production.

For over a century, apple growers have manually tied down branches of young trees to boost crop productivity. While the exact reason behind this practice remains unclear, it is believed to redirect the tree's resources, such as carbon and nutrients, towards reproductive growth (flowering and fruiting) rather than vegetative growth (branches and leaves).

However, some apple trees naturally exhibit a weeping growth pattern, which led researchers to investigate the underlying basis. In a recent study published in , scientists identified a in a gene called MdLAZY1A, which plays a major role in controlling weeping growth in apple trees.

This rare mutation occurs in less than 1% of trees but could hold the key to enhancing apple cultivation. By using advanced genetic sequencing techniques and a “forward genetics” approach, researchers analyzed over 1,000 offspring of weeping apple cultivars. Through this process, they successfully isolated the genetic determinant responsible for the weeping trait.

The senior author of the study, Kenong Xu, explained that the findings could be applied to existing apple cultivars to encourage more downward growth or wider-spreading branches, leading to increased productivity and reduced labor costs for tying branches down.

The identified mutation involves a single nucleotide substitution in the MdLAZY1A gene. With the knowledge of this , plant geneticists could potentially use /Cas-9 technology to develop new apple cultivars with weeping-like growth.

The research not only sheds light on the of the weeping architecture in apple trees but also paves the way for targeted genetic modifications to improve apple cultivation and fruit production. Laura Dougherty, the paper's first author, is a former postdoctoral researcher at Cornell, and the study includes contributions from other esteemed researchers in the field of plant science.

Source: Cornell University

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