Photo credit: CIAT
Solanum chilense growing in a sand dune. Source: TGRC
Different combinations of morpho-physiological traits are responsible for tolerance to drought in wild tomatoes Solanum chilense and Solanum peruvianum
by Gerardo Tapia, José Méndez and Luis Inostroza
Background and Aims
Herbaceous species can modify leaf structure during the growing season in order to respond to drought stress and reduce water loss. Evolutionary processes can select combinations of traits in plants for efficient water use in restricted environments. This study investigated plant traits that mediate the adaptation and acclimation to water stress in two herbaceous drought tolerant species.
Several anatomical, morphological and physiological traits related to stems and leaves were examined under optimal watering (OW) and a long period of restricted watering (RW) conditions in 11 accessions from three species of the Solanaceae family (Solanum chilense, S. peruvianum and S. lycopersicum). The relationships between these traits were tested using linear regression and principal component analysis.
Significant differences were found for anatomical traits between the three species under both OW and RW treatments, where leaf area (LA) correlated with stem diameter (StemD). Proline and total carbohydrates (TC) accumulated highly in S. chilense and S. peruvianum, respectively, and these osmolytes were strongly correlated with increase of osmotic potential (Ψπ). The stomatal density (SD) varied between species but not between acclimation treatments, while the stomatal rate (SR) was significantly higher in wild tomatoes. The tomato species exhibited a strong positive relationship between stem growth rate (SGR) and a group of traits together expressed as total stomatal number (TSt). TSt was described in this research by the integration of LA, SD, Height (H) and internode length (IntL).
It is proposed that constitutive adaptations as well as modifications by acclimation that mediate RW treatment plays an important role in tolerance to drought stress in herbaceous plants. The capacity of growth under drought stress was not associated with any single combination of traits in wild tomatoes, since the two species differed in relative levels of expression of various phenotypical traits.
See the text: Wiley Online Library