Functional Plant Biology
Volume 42 Number 1 2015
FP14043Transcriptional regulation of phosphate transporters from Lolium perenne and its mycorrhizal symbionts in response to phosphorus supply
Phosphorus is essential for plant growth but little is known about its acquisition in pasture grasses. We isolated a phosphate transporter gene from perennial ryegrass together with genes associated with mycorrhizal fungal colonisation and studied how these were affected by varying phosphate supply. This research will help understand phosphorus uptake in pasture grasses and how the relationship with symbiotic mycorrhizal fungi supports this.
FP14078Radial oxygen loss and physical barriers in relation to root tissue age in species with different types of aerenchyma
Plants grown under flooding conditions display a large variation in aeration strategies in order to maintain suitable levels of oxygen to survive. We investigated these responses in three lowland grassland species, focusing on radial oxygen loss from roots, with different arrangement of aerenchyma. We found that hypoxia response as the oxygenation of roots depends on species and we discuss the physiological implications of the different responses.
FP14101PvLOX2 silencing in common bean roots impairs arbuscular mycorrhiza-induced resistance without affecting symbiosis establishment
Arbuscular mycorrhizal colonization elicits mycorrhizal-induced resistance (MIR), an enhanced pathogen defence response. To investigate the role of the oxylipin biosynthetic pathway in this phenomenon, we silenced lipoxygenases in normally AM colonized common bean roots and observed MIR impairment against a foliar pathogen. These findings provide novel insights into the onset of MIR, and will eventually be of great benefit to agriculture.
FP14159Suppression of starch synthesis in rice stems splays tiller angle due to gravitropic insensitivity but does not affect yield
In rice (Oryza sativa L.), tiller angle – defined as the angle between the main culm and its side tillers – is one of the important factors involved in light use efficiency. Our analysis of a low stem starch mutant revealed suppression of starch synthesis in rice stems splays tiller angle due to gravitropic insensitivity but does not necessarily impact dry matter production. These findings provided new insights for rice breeding to improve plant architecture.
FP14095Light-stimulated heat tolerance in leaves of two neotropical tree species, Ficus insipida and Calophyllum longifolium
In the tropics, climate warming and intensified extreme weather events may lead to elevated peak temperatures transgressing the limit of thermal tolerance in plant leaves, causing permanent tissue damage. We demonstrate experimentally that light absorbed by leaves in excess of photosynthetic utilisation ameliorates thermal tolerance. Our results contradict the widespread notion that exposure of leaves to high light in combination with heat aggravates leaf damage.
FP14100Increasing nitrogen supply stimulates phosphorus acquisition mechanisms in the fynbos species Aspalathus linearis
The mechanisms for growth of Aspalathus linearis (Rooibos tea) in the nutrient-poor soils of the Core Cape subregion, and its response to combined addition of N and P, are not known. When addition of N induced low availability of P, the species increased partitioning of resources towards acquisition of P and also enhanced growth. Our findings show that plant growth is colimited by multiple resources.
FP14040Foliar trait contrasts between African forest and savanna trees: genetic versus environmental effects
Plants are generally assumed to become more sclerophyllous as precipitation declines – but not in West Africa where leaf mass per unit area actually declines with decreasing rainfall. Foliar potassium concentrations increase dramatically with increasing aridity, also differentiating ecotonal forest and savanna species. This suggests an important but as yet unidentified role for K as a modulator of tropical vegetation structure and function.
FP14115Changes in timing of water uptake and phenology favours yield gain in terminal water stressed chickpea AtDREB1A transgenics
Effect of DREB1A on the yield under stress of transgenic chickpea was tested in a lysimetric system. Only modest yield benefits were found and higher yield related with higher water availability during the reproduction and grain filling period and the capacity to successfully produce filled pods from late flowers. This confirms earlier results obtained with chickpea germplasm.
FP14097Potential advantages of highly mycotrophic foraging for the establishment of early successional pioneer plants on sand
Nutrient uptake through symbiotic mycorrhizal fungi can be considered as an alternative to nutrient acquisition via roots. A comparison of both strategies in sand pioneer plants revealed that in ‘mycorrhiza strategists’ the enlargement of the absorptive surface area was clearly promoted and led to enhanced soil phosphorus depletion compared with ‘root strategists’. Thus, mycorrhizal fungi may be an important factor for the establishment of some plant species in nutrient poor sandy habitats.
FP14062Nitrogen supply controls vegetative growth, biomass and nitrogen allocation for grapevine (cv. Shiraz) grown in pots
Apart from water, nitrogen is also an important limiting factor in grape growing. The effects of nitrogen deficiency were investigated with 2-year-old Vitis vinifera cv. Shiraz plants grown in pots and exposed to various N supplies under well watered conditions. Primary axis elongation, leaf emergences on the primary and the secondary axes and lamina area expansion were significantly inhibited by nitrogen deficiency from flowering in an intensity-dependent manner.