Pivotal Roles of Cryptochromes 1a and 2 in Tomato Development and Physiology

Abstract

Cryptochromes are flavin-containing blue/UVA light photoreceptors that regulate various plant light-induced physiological processes. In Arabidopsis (<i>Arabidopsis thaliana</i>), cryptochromes mediate de-etiolation, photoperiodic control of flowering, entrainment of the circadian clock, cotyledon opening and expansion, anthocyanin accumulation, and root growth. In tomato (<i>Solanum lycopersicum</i>), cryptochromes are encoded by a multigene family, comprising <i>CRY1a</i>, <i>CRY1b</i>, <i>CRY2</i>, and <i>CRY3</i> We have previously reported the phenotypes of tomato <i>cry1a</i> mutants and <i>CRY2</i> overexpressing plants. Here, we report the isolation by targeting induced local lesions in genomes, of a tomato <i>cry2</i> knock-out mutant, its introgression in the indeterminate Moneymaker background, and the phenotypes of <i>cry1a</i>/<i>cry2</i> single and double mutants. The <i>cry1a</i>/<i>cry2</i> mutant showed phenotypes similar to its Arabidopsis counterpart (long hypocotyls in white and blue light), but also several additional features such as increased seed weight and internode length, enhanced hypocotyl length in red light, inhibited primary root growth under different light conditions, anticipation of flowering under long-day conditions, and alteration of the phase of circadian leaf movements. Both cry1a and cry2 control the levels of photosynthetic pigments in leaves, but cry2 has a predominant role in fruit pigmentation. Metabolites of the sterol, tocopherol, quinone, and sugar classes are differentially accumulated in <i>cry1a</i> and <i>cry2</i> leaves and fruits. These results demonstrate a pivotal role of cryptochromes in controlling tomato development and physiology. The manipulation of these photoreceptors represents a powerful tool to influence important agronomic traits such as flowering time and fruit quality.