Dwarf mutants in plants are crucial to elucidate regulatory mechanisms for plant growth and development. A new dwarf mutant named lingering hope (linho) was isolated from sunflower (Helianthus annuus). With the aim to characterize this new brachytic mutant, we performed genetic analysis and several morphometric data were collected. The hormonal profile and the photosynthetic performance were also investigated in this mutant. The brachytic trait is controlled by a recessive nuclear gene. The reduction of plant height is not due to the production of fewer phytomers but the phenotype depends on shorter internodes especially during reproductive stage. The mutant and wild type (WT) phenotype is normal from the cotyledonary stage to the first two pairs of leaves. However, after this vegetative stage, linho leaves show an altered ratio length/width of the blade, delayed greening phenomena and chlorosis in proximal area of the lamina; moreover, asymmetric shape and epinasty have been frequently observed. The linho mutant has defects in inflorescence development because blossoming is not regular. In several organs of linho and WT we analyzed endogenous hormonal level of abscisic acid, jasmonic acid, indoleacetic acid, salicylic acid (SA) and gibberellins. Results demonstrate that the brachytic trait is not associated to a specific hormonal reduction but the endogenous SA content in some organs (i.e. young leaves in reproductive stage) of the mutant is very high. SA plays key role in plant response to abiotic and biotic stresses although SA effects on plant growth and development are very complex and not still well understood. To evaluate the photosynthetic performance and the light energy dissipation mechanisms, gas exchange and fluorescence measurements were determined in linho and WT plants. The CO 2 assimilation rate significantly decreased in linho, due to the effects of both stomatal and non-stomatal constraints. In addition, the reduction of both photochemical efficiency of photosystem II and non-photochemical quenching at saturating light intensity indicated a lower capacity of linho to dissipate the absorbed light energy, associated with a reduced content of chlorophylls and carotenoids. These results suggest that the linho mutant could be useful to investigate the role of SA during plant growth and development
Genetic and physiological characterization of a new brachytic sunflower mutant, lingering hope (linho).
MARIOTTI L.;FAMBRINI M.;SCARTAZZA A.;PICCIARELLI P.;PUGLIESI C.
2017-01-01
Abstract
Dwarf mutants in plants are crucial to elucidate regulatory mechanisms for plant growth and development. A new dwarf mutant named lingering hope (linho) was isolated from sunflower (Helianthus annuus). With the aim to characterize this new brachytic mutant, we performed genetic analysis and several morphometric data were collected. The hormonal profile and the photosynthetic performance were also investigated in this mutant. The brachytic trait is controlled by a recessive nuclear gene. The reduction of plant height is not due to the production of fewer phytomers but the phenotype depends on shorter internodes especially during reproductive stage. The mutant and wild type (WT) phenotype is normal from the cotyledonary stage to the first two pairs of leaves. However, after this vegetative stage, linho leaves show an altered ratio length/width of the blade, delayed greening phenomena and chlorosis in proximal area of the lamina; moreover, asymmetric shape and epinasty have been frequently observed. The linho mutant has defects in inflorescence development because blossoming is not regular. In several organs of linho and WT we analyzed endogenous hormonal level of abscisic acid, jasmonic acid, indoleacetic acid, salicylic acid (SA) and gibberellins. Results demonstrate that the brachytic trait is not associated to a specific hormonal reduction but the endogenous SA content in some organs (i.e. young leaves in reproductive stage) of the mutant is very high. SA plays key role in plant response to abiotic and biotic stresses although SA effects on plant growth and development are very complex and not still well understood. To evaluate the photosynthetic performance and the light energy dissipation mechanisms, gas exchange and fluorescence measurements were determined in linho and WT plants. The CO 2 assimilation rate significantly decreased in linho, due to the effects of both stomatal and non-stomatal constraints. In addition, the reduction of both photochemical efficiency of photosystem II and non-photochemical quenching at saturating light intensity indicated a lower capacity of linho to dissipate the absorbed light energy, associated with a reduced content of chlorophylls and carotenoids. These results suggest that the linho mutant could be useful to investigate the role of SA during plant growth and developmentI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
