Iron deficiency in rice shoots: identification of novel induced genes using RDA and possible relation to leaf senescence

Abstract

Rice plants are highly susceptible to Fe-deficiency. Under nutrient deprivation, plant cells undergo extensive metabolic changes for their continued survival. To provide further insight into the pathways induced during Fe-deficiency, rice seedlings were grown for 3, 6 and 9 days in the presence or absence of Fe. Using RDA (Representational Difference Analysis), sequences of 32 induced genes in rice shoots under Fe-deficiency were identified. About 30% of the sequences found have been previously reported as responsive to other abiotic and even biotic stresses. However, this is the first report that indicates their relation to Fe deprivation. Differential expression of selected genes was confirmed by semi-quantitative RT-PCR analysis. The identification of classical senescence-related sequences, such as lipase EC 3.1.1.-, ubiquitin-conjugating enzyme EC 6.3.2.19, beta-Glucosidase EC 3.2.1.21 and cysteine synthase EC 2.5.1.47, besides the higher accumulation of total soluble sugars prior to the decrease of total chlorophyll content in Fe-deficient leaves, indicate that sugar accumulation may be one of the factors leading to premature leaf senescence induced by Fe-deficiency.

Natural variation in iron use efficiency and mineral remobilization in cucumber (Cucumis sativus)

“…Nitrogen deficiency stress is known to result in premature senescence (Crafts-Brandner et al 1998). Fe deficiency may also accelerate senescence (Sperotto et al 2008(Sperotto et al , 2007. In our experiments, K was remobilized earlier time points from MW, and P remobilization occurred at earlier time points in Ashley when Fe was withheld.…”

Metabolite profile changes in xylem sap and leaf extracts of strategy I plants in response to iron deficiency and resupply

“…Therefore, the increase in leaf free aminoacids is likely to result from proteolysis processes occurring in the shoot. In barley and rice (two Strategy II species), Fe deficiency results in an accelerated senescence both in old leaves (Maruyama et al, 2005; Sperotto et al, 2007; Higuchi et al, 2011) and roots (Sperotto et al, 2008), leading to the hypothesis that aminoacids can be reutilized in young leaves of these plants (Higuchi et al, 2011). An Arabidopsis thylakoid proteomic study suggests that Fe-deficient leaves bear changes similar to those observed during senescence (Laganowsky et al, 2009).…”

kNACking on heaven’s door: how important are NAC transcription factors for leaf senescence and Fe/Zn remobilization to seeds?

“…Decline of photosynthesis, chloroplast and chlorophyll degradation, dismantling of biomolecules and decrease in cellular metabolic activities take place, which result in available nutrients and metabolites that can be transported from source (the tissue that supplies nutrients, most commonly green tissues) to sink (the net importer of nutrients, younger or reproductive organs) through the vascular system (Thomas, 2013). Part of leaf senescence seems to be regulated by sugar levels (Rolland et al, 2006; Sperotto et al, 2007), since a senescence-related loss of chlorophyll or protein can be induced by increased sugar contents (Wingler et al, 1998). Hormones and nutrients also contribute to regulation of senescence in source tissues, especially cytokinins, which have a senescence-delaying effect (Sperotto et al, 2009; Davies and Gan, 2012).…”