Banca de QUALIFICAÇÃO: ANA PAULA AVELINO DOS SANTOS

Uma banca de QUALIFICAÇÃO DE MESTRADO foi cadastrada pelo programa.

DISCENTE: ANA PAULA AVELINO DOS SANTOS
DATA: 25/05/2016
HORA: 08:30
LOCAL: Sala SS1 - Depto. de Biologia Celular e Genética - CB/UFRN
TÍTULO:

Involvement of source-sink relation and carbon starvation in the regulation of reserve mobilization in sunflower during late seedling establishment under continuous darkness

RESUMO:

Reserve mobilization, metabolite partitioning, and reserve-degrading enzyme activities were studied in sunflower seedlings cultivated in vitro under 12-h photoperiod or in the absence of light to investigate the involvement of source-sink relation and carbon starvation in the mechanisms that regulate reserve mobilization during the exposure to continuous darkness. At the first 24 h of treatment (acclimation phase), the absence of light did not affect growth, but restricted carbon and nitrogen utilization, indicated by sugar and amino acid accumulation in the different seedling parts. After 5 days of treatment (survival phase), extended exposure to darkness limited growth and retarded storage lipid and protein mobilization due to carbon starvation, evidenced by the depletion of carbohydrates in cotyledons and hypocotyl, as well as the consume of amino acids in hypocotyl and roots. Alterations in the source-sink relation may have been a response to extended darkness, instead of a mechanism utilized to regulate reserve mobilization, as these alterations cannot be associated with negative feedback mediated by metabolite accumulation. Storage lipid degradation depended, at least in part, on mechanisms that co-ordinately regulate the activities of lipases and isocitrate lyase, but the activities of acid proteases and amylases could not be directly related to the regulation of storage protein and starch hydrolysis, respectively. Taking these results together, it is possible to suggest that reserve mobilization in sunflower seedlings cultivated in the dark may be regulated by mechanisms that perceive the absence of light and predict carbon starvation, adjusting reserve utilization according to future energy demands to allow, at least in short term, seedling survival.

PALAVRAS-CHAVE:

Carbon starvation; Helianthus annuus L.; reserve mobilization; reserve-degrading enzymes; source-sink relation

PÁGINAS: 19
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica

MEMBROS DA BANCA:
Externo ao Programa - 2294466 - CRISTIANE ELIZABETH COSTA DE MACEDO
Interno - 1880243 - DANIEL CARLOS FERREIRA LANZA
Presidente - 1453487 - KATIA CASTANHO SCORTECCI