RESUMO
The drought stress tolerance of two Solanum tuberosum subsp. andigena landraces, one hybrid (adgxtbr) and Atlantic (S. tuberosum subsp. tuberosum) has been evaluated. Photosynthesis in the Andigena landraces during prolonged drought was maintained significantly longer than in the Tuberosum (Atlantic) line. Among the Andigena landraces, 'Sullu' (SUL) was more drought resistant than 'Negra Ojosa' (NOJ). Microarray analysis and metabolite data from leaf samples taken at the point of maximum stress suggested higher mitochondrial metabolic activity in SUL than in NOJ. A greater induction of chloroplast-localized antioxidant and chaperone genes in SUL compared with NOJ was evident. ABA-responsive TFs were more induced in NOJ compared with SUL, including WRKY1, mediating a response in SA signalling that may give rise to increased ROS. NOJ may be experiencing higher ROS levels than SUL. Metabolite profiles of NOJ were characterized by compounds indicative of stress, for example, proline, trehalose, and GABA, which accumulated to a higher degree than in SUL. The differences between the Andigena lines were not explained by protective roles of compatible solutes; hexoses and complex sugars were similar in both landraces. Instead, lower levels of ROS accumulation, greater mitochondrial activity and active chloroplast defences contributed to a lower stress load in SUL than in NOJ during drought.
Assuntos
Adaptação Fisiológica , Desastres , Regulação da Expressão Gênica de Plantas , Solanum tuberosum/genética , Solanum tuberosum/fisiologia , Transportadores de Cassetes de Ligação de ATP/genética , Genótipo , Mitocôndrias/genética , Mitocôndrias/fisiologia , Chaperonas Moleculares/genética , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , Fotossíntese , Proteínas de Plantas/genética , Fatores de Transcrição/genéticaRESUMO
A drought screen identified accessions of Solanum tuberosum ssp. andigena that showed varying degrees of physiological acclimation or adaptation to repeated drought stress. The accessions also showed variable tuber phenotypes from small tubers that failed to develop in an accession that showed photosynthetic adaptation to normal tubers in an accession with a phenotype showing some degree of photosynthetic adaptation and acclimation. Using microarray data, we correlated the expression of genes associated with carbon metabolism with the tuber development phenotypes under drought. Genes associated with sucrose and starch metabolism showed responses consistent with starch deficiency in the adapted accession and normal starch deposition in the intermediate accession. Starch phosphorylase and glycogen bound starch synthase were induced in the adapted accession, which had abnormal tuber development. Genes associated with trehalose were induced in the intermediate accession with normal tuber development. Genes associated with respiration were also induced in the intermediate accession, and a pattern compatible with the existence of a 3PGA recovery pathway was revealed. Expression of thioredoxin genes also correlated with tuber development phenotypes under drought stress. The data suggest differential regulation of starch deposition in accessions of Andigena with different abilities to respond to drought stress.