Researchers have made a groundbreaking discovery in plant genetics that could revolutionize apple tree cultivation. In a recent study published in Plant Physiology, scientists identified a mutation in the gene MdLAZY1A that causes the distinctive “weeping” architecture in apple trees, where branches grow downwards. This rare mutation, known as MdLAZY1A-W, was found to be the genetic determinant responsible for the weeping growth phenotype in apple trees.

Traditionally, growers have manually tied down apple branches during the early stages of tree growth to enhance crop productivity. However, the new findings suggest that understanding and utilizing the weeping gene mutation could lead to more efficient and cost-effective methods of improving orchard fruit production. By redirecting the tree’s growth pattern, more resources can be channeled toward reproductive growth (flowering and fruiting) rather than vegetative growth (branches and leaves).

The research team, led by senior author Kenong Xu from Cornell AgriTech, noted that the weeping allele, MdLAZY1A-W, occurs in less than 1% of apple trees. With this gene mutation now identified, plant geneticists may explore the potential of using CRISPR/Cas-9 gene editing technology to develop apple cultivars with weeping-like growth patterns. Transgenic studies confirmed that inserting the weeping allele into a standard royal gala apple cultivar caused the tree to grow downward.

The study utilized a “forward genetics” approach, examining over 1,000 offspring of weeping cultivars to identify the genetic determinant responsible for the weeping growth phenotype. Researchers hope to apply this knowledge to improve apple cultivation and other crop yields by understanding the genetic control of apple tree architecture. This groundbreaking discovery opens up new possibilities for tree architecture improvement in the agricultural industry.

References

• Dougherty, L., Borejsza-Wysocka, E., Miaule, A., Wang, P., Zheng, D., Jansen, M., Brown, S., Piñeros, M., Dardick, C., & Xu, K. (2023). A single amino acid substitution in MdLAZY1A dominantly impairs shoot gravitropism in Malus. Plant Physiology, kiad373. https://doi.org/10.1093/plphys/kiad373
• Ramanujan, K. & Cornell Chronicle. (2023, July 20). Gene variation makes apple trees ‘weep,’ improving orchards. Cornell Chronicle; Cornell University. https://news.cornell.edu/stories/2023/07/gene-variation-makes-apple-trees-weep-improving-orchards-1