Source-sink regulation of cotyledonary reserve mobilization during cashew (Anacardium occidentale) seedling establishment under NaCl salinity.
Seedling establishment is a critical process to crop productivity, especially under saline conditions. This work was carried out to investigate the hypothesis that reserve mobilization is coordinated with salt-induced inhibition of seedling growth due to changes in source-sink relations. To test this hypothesis, cashew nuts (Anacardium occidentale) were sown in vermiculite irrigated daily with distilled water (control) or 50mM NaCl and they were evaluated at discrete developmental stages from the seed germination until the whole seedling establishment. The salt treatment coordinately delayed the seedling growth and the cotyledonary reserve mobilization. However, these effects were more pronounced at late seedling establishment than in earlier stages. The storage protein mobilization was affected by salt stress before the lipid and starch breakdown. The globulin fraction represented the most important storage proteins of cashew cotyledons, and its mobilization was markedly delayed by NaCl along the seedling establishment. Free amino acids were mostly retained in the cotyledons of salt-treated seedlings when the mobilization of storage proteins, lipids and starch was strongly delayed. Proline was not considerably accumulated in the cotyledons of cashew seedlings as a response to NaCl salinity. According to these results it is noteworthy that the salt-induced inhibition of seedling growth is narrowly coordinated with the delay of reserve mobilization and the accumulation of hydrolysis products in cotyledons. Also, it was evidenced that free amino acids, especially those related to nitrogen transport, are potential signals involved in the regulation of storage protein hydrolysis during cashew seedling establishment under NaCl salinity.
Voigt
Eduardo Luiz
EL
Departamento de Bioquímica e Biologia Molecular, Laboratório de Metabolismo de Plantas, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.
Almeida
Tânia Dias
TD
Chagas
Roberta Magalhães
RM
Ponte
Luiz Ferreira Aguiar
LF
Viégas
Ricardo Almeida
RA
Silveira
Joaquim Albenísio Gomes
JA
D000596:Amino Acids / Q000378:metabolism; D031021:Anacardium / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D018533:Biomass; D018548:Cotyledon / Q000187:drug effects / Q000378:metabolism*; D050356:Lipid Metabolism / Q000187:drug effects; D010940:Plant Proteins / Q000378:metabolism; D054712:Salinity; D036226:Seedlings / Q000187:drug effects* / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D012995:Solubility / Q000187:drug effects; D013213:Starch / Q000378:metabolism
D000596:Amino Acids; D010940:Plant Proteins; D012965:Sodium Chloride; D013213:Starch