Plastome from high-altitude Lycopersicon hirsutum does not improve low-temperature tolerance of cold-sensitive Lycopersicon esculentum

Abstract

The role of the chloroplast in suboptimal-temperature tolerance was studied by comparing growth and photosynthesis of an alloplasmic tomato cybrid of L. esculentum c.v. LRC with chloroplasts from a more cold-tolerant L. hirsutum accession (LA 1777) with the performace of both euplasmic parents. Plants were grown in two adjacent greenhouses with an optimal (25/20°C) and suboptimal (16/14°C) temperature regime, under a minimum PPFD of 225 µmol m-2 s-1 during a 12-h photoperiod. Irrespective of the temperature regime, shoot biomass production was similar in L. esculentum and the cybrid. Shoot biomass production of the plastome donor L. hirsutum was less inhibited by suboptimal growth temperature than in LRC and the cybrid. Photosynthetic rates of the cybrid and LRC at both growth conditions were similar but lower than the values of L. hirsutum. Leaves of LRC, the cybrid and L. hirsutum grown at 25/20°C demonstrated comparable temperature dependencies of maximum photosynthetic capacity (Pmax). In contrast to LRC and the cybrid, Pmax was significantly increased at all temperatures in leaves of L. hirsutum acclimated to 16/14°C. The alloplasmic tomato was more susceptible to chilling-induced photoinhibition than its parents. It is concluded that combining the L. esculentum genome with a L. hirsutum plastome did not improve growth and photosynthetic performance of the domestic tomato at suboptimal temperature and that low-temperature acclimation of chloroplast functioning in tomato is not controled by the plastome.