Despite the remarkable morphological diversity in the leaf shape, usually higher plants maintain a flat lamina to ensure the desirable surface-to-volume ratio. The control of expansion of a flattened lateral organ is only partially known and the characterization of leaf mutants can be a useful strategy to add new information, as demonstrated in dicots with recessive mutants of model species. In sunflower, the dominant mutant Basilicum Leaf (BL) is characterized by prominent downward leaf curling. The central end of the present work is the detailed study of the BL phenotype to characterize the effects of this mutation, at organ and cellular levels, on both morphological and physiological traits. The geometry of mature leaves is obviously altered in BL plants because the lamina surfaces are downward curled and display a different length/width ratio with respect to wild type. The area of BL leaves is higher than that of wild type while the BL leaf perimeter is reduced. In BL leaves, the perimeter to the square root of area ratio is also abnormally low compared to the value of a flat sunflower lamina. These results suggest that the dominant mutation induces a deep change of the ratio between lamina and marginal growth. In addition, the epidermis and mesophyll of BL leaves comprised higher size pavement and palisade cells compared to those of wild type, indicating that the BL gene also control cell shape changes in the formation of the leaf lamina. Other leaf traits such as photosynthetic pigment content, pattern of minor vein architecture, margin type and stomatal density are affected by the mutation. In BL plants, the longitudinal axis of both cotyledons and ray flower corollas shows an unusual curvature while the diameter of shoot and inflorescence meristems is reduced. In mutant leaves, the gas exchange performance is influenced by low stomata conductance while the CO2 assimilation rate is also depressed by a depleted Rubisco activity. Together, these data demonstrate the pleiotropic nature of the BL mutation, which affects a number of morphological aspects of flattened lateral organs as well as physiological parameters in sunflower.
|Autori:||FAMBRINI M; DEGL'INNOCENTI E; GUIDI L; PUGLIESI C|
|Titolo:||The dominant Basilicum Leaf mutation of sunflower controls leaf development multifariously and modifies the photosynthetic traits|
|Anno del prodotto:||2010|
|Digital Object Identifier (DOI):||10.1016/j.flora.2010.01.001|
|Appare nelle tipologie:||1.1 Articolo in rivista|