Field evaluation of CRISPR-Cas9-driven brachytic and jointless pedicel tomatoes identifies an association between the high extra-large-sized fruit yield of the brachytic-mediated shortened tomato and the jointless2

Abstract

Fresh-market tomato is one of the most important vegetables in the United States (US), and novel, cost-effective labor solutions are an important issue in current fresh-market tomato production. The shortened stem driven by the brachytic (br) and the jointless pedicel driven by the jointless2 (j2) are two important traits that would contribute to knowledge-based breeding; based on these traits, an appropriate plant architecture can be designed for ground cultivation systems that will ultimately enable mechanical harvesting. We aimed to evaluate the effect of CRISPR-Cas9-driven shortened plant architecture and jointless pedicel on the yield and horticultural performance of fresh-market tomatoes using a ground cultivation system in an open field. We conducted field trials during three successive seasons in 2020 and 2021 using the fresh-market tomato variety Fla. 8059 (a non-brachytic jointed pedicel tomato; BR/BR:J2/J2; wild-type) and its three different CRISPR-Cas9-driven mutants, a brachytic jointed pedicel Fla. 8059 (br/br:J2/J2), a non-brachytic jointless pedicel Fla. 8059 (BR/BR:j2/j2), and a brachytic jointless pedicel Fla. 8059 (br/br:j2/j2). Field evaluations confirmed that the total yield of the mutants was not significantly different from the yield of the wild-type. However, there was a significant association between the high extra-large-sized fruit yield of the br mutant and the j2 mutation. Field evaluations also revealed a clear positive impact of the br mutation on the high proportion of fruits laying on the raised plastic bed. Our results contribute to the optimization of fresh-market tomato architecture for developing shortened jointless pedicel varieties and the adoption of low input management practices.