These genetic markers can be used in tomato breeding to generate varieties of fresh-market tomatoes with compact growth characteristics necessary to enable mechanical harvesting to decrease harvesting costs. In the U.S., fresh-market and processing tomatoes are the two most commonly consumed types and account for more than $2.6 billion of revenue annually. Processing tomatoes have a compact growth habit that allows them to grow without staking and harvested mechanically. By contrast, fresh-market tomato varieties have long vines that require manual staking, tying, and pruning. Additionally, the stakes supporting these vines prevent the use of cost-efficient mechanical harvesting. The compact growth habit of processing tomato varieties is due to a shortened internode that reduces stem length and this trait is controlled by several genes.
Researchers at the University of Florida have identified multiple genes responsible for this trait. The genetic markers associated with a shortened internode allow tomato breeders to use marker-assisted breeding to efficiently introduce this trait into fresh-market tomatoes to reduce production costs. Alternatively, with the identification of the genes responsible for compact growth habit, gene editing (e.g., through use of CRISPR-Cas9) can be used to create new cultivars.
Creation of new cultivars by gene editing and/or genetic selection of tomato varieties that have a compact growth habit allowing for reduced production costs that enables growth without staking to increase yield and reduce production and harvesting costs
Identification of multiple genes and associated genetic markers in the tomato genome for compact growth habit enables more efficient breeding of varieties with specific phenotypic traits, such as shortened internodes and concentrated fruit setting. Creating new cultivars with the compact growth trait can be achieved by a number of routes such as crossing designated tomato plants so that the progeny contains and expresses the desirable brachytic gene variant; or introgressing the gene variant into fresh-market tomato varieties through several generations of back-crossing; or using gene editing techniques to modify the genes responsible for short internode length. The resulting tomato varieties expressing the brachytic gene variant(s) have shorter distances between nodes and more condensed fruit distribution, making their production less labor intensive and suitable for mechanical harvesting.
