Data di Pubblicazione:
2015
Citazione:
A FORWARD GENETICS APPROACH TO STUDY SEED AND SEEDLING DEVELOPMENT IN MAIZE / M. Persico ; supervisor: G. Consonni ; co-supervisor: F. F. Nocito. DIPARTIMENTO DI SCIENZE AGRARIE E AMBIENTALI - PRODUZIONE, TERRITORIO, AGROENERGIA, 2015 Dec 15. 28. ciclo, Anno Accademico 2015. [10.13130/m-persico_phd2015-12-15].
Abstract:
Embryogenesis, germination and early phases of seedling growth represent critical phases in the plant life cycle and are probably the most important events in determining the success of an annual plant.
A rapid and robust emergence positively influences the capacity of the plant to take advantage of the favourite environment and to compete with its neighbours. In the perspective of a more sustainable agriculture specific characters are envisaged for a crop seedling, such as the resistance to environmental critical abiotic as well as biotic factors. For these reasons key factors subtending plant developmental process and contributing to the achievement of a productive and robust plant have to be searched inside the genetic network that control embryo and seedling development.
Among the different aspects affecting seedling development the two that will be analysed in this study play an important role also in the interplay with the environment. Hormones are endogenous signals governing seedling growth and architecture establishment but at the same time are able to induce plant response to environmental stress. Wax deposition is required for determining a correct embryo and seedling development, and provides, beside that, a protective barrier that plants produce in their early developmental phases to defend themselves from pathogens as well as from variation in environmental abiotic components, such as temperature and water availability.
Here, we report the characterization of the mutants lilliputian 1-1 (lil1-1) and fused leaves 1-1 (fdl1-1), both ascribable to defective seedling (des) maize mutants.
lilliputian 1-1 (lil1-1) is a monogenic recessive mutant of maize, isolated from an active Mutator (Mu) stock and attributed to the insertion of a Mutator1 element in the first exon of a the gene encoding the BR C-6 oxidase. The enzyme belongs to the superfamily of CYP85A proteins and catalyzes the final steps of brassinosteroid synthesis. lil1-1 mutant exhibits a reproducible phenotype consisting of a large primary root, extremely reduced stature and crinkly leaves. Recently, another dwarf mutant of maize impaired in the same brassinosteroid C-6 oxidase and showing a very similar phenotype of lil1-1 has been characterized and the corresponding gene was termed brasssinosteroid deficient 1 (brd1)
Allelism between the two mutant alleles has been demonstrated in this work. Moreover, it has been observed that the exogenous application of brassinolide to the lil1 mutant seedlings resulted in a partial recovery of the lil1-1 phenotype. This observation is in agreement to what previously observed for brd1-m in maize and other Br-deficient mutants in Arabidopsis, rice and tomato.
Differently from some of these mutants, i.e det2 of Arabidopsis, lil1 genotype does not influence the seed formation and development. It is evident that the comparison between homozygous lil1-1 mutant and Li11-1 wild-type seeds from the same segregating ear did not highlight any difference in weight. In addition, F2 progeny ears obtained from F1 heterozygous Lil11/lil1-1 or homozygous Lil1-1/Lil1-1 plants showed the same average kernel number and total kernel weight per ear and the average weight of single kernel.
BRs are also involved in the modulation of stress responses. Water loss assays and measurement of gas exchange demonstrated that lil1-1 plants lost less water and maintained efficient gas exchange under drought stress for longer time than wild-type siblings.
Our hypothesis is that lil1-1 mutant is more tolerant to drought stress because it is by default in a physiological water stress condition. A similar interpretation has been proposed to explain the behaviour of the det2 mutant in Arabidopsis that is deficient in a steroid reductase. The det2 mut
Tipologia IRIS:
Tesi di dottorato
Keywords:
fdl1-1; lil1-1; maize, cuticular waxes; brassinosteroids
Elenco autori:
M. Persico
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