Functional Plant Biology

Contents Volume 34 Issue 8 2007

Regulation of lutein biosynthesis and prolamellar body The regulation of the carotenoid biosynthesis pathway is formation in Arabidopsis extremely important, and yet the mechanisms are far from clear. Abby J. Cuttriss, Alexandra C. Chubb, Ali Alawady, These authors investigated carotenoid gene expression and Bernhard Grimm and Barry J. Pogson 663–672 ultrastructural changes of the etioplasts in response to herbicide and/or light treatment, and demonstrate that carotenoid isomerase and ε-cyclase may play a key role in controlling lutein biosynthesis.

Effects of polyploidy on photosynthetic properties and Polyploidy affects through changes in anatomy in leaves of Phlox drummondii morphology, anatomy and biochemistry. These authors examined Poonam Vyas, Madho Singh Bisht, Shin-Ichi Miyazawa, effects of chromosome doubling and genome stabilisation on Satoshi Yano, Ko Noguchi, Ichiro Terashima and photosynthesis and leaf anatomical properties in diploid Phlox Sachiko Funayama-Noguchi 673–682 drummondii, and its corresponding synthetic autotetraploids at the initial and 11th generations. They found an increase in photosynthesis associated with polyploidy, due to both chromosome doubling and some subsequent adjustment.

Plant isotopic composition provides insight into In order to unravel the specific mechanisms involved in host mechanisms underlying growth stimulation by AM fungi plant growth enhancement by native arbuscular mycorrhizal in a semiarid environment fungi (AMF), growth of two dryland shrubs on a degraded soil in José I. Querejeta, Michael F.Allen, María M. Alguacil a semi-arid environment was studied. The authors examined the and Antonio Roldán 683–691 relationships among mycorrhizal, nutrient, isotopic and growth variables; their results highlight the critical role that drought- adapted native AMF can play improving the water relations in drought-prone environments.

δ13C of organic matter transported from the leaves to the Post-photosynthetic isotope fractionation may alter the roots in Eucalyptus delegatensis: short-term variations isotopic signal imprinted on organic matter during primary and relation to respired CO2 carbon fixation by Rubisco. To characterise the influence of post- Arthur Gessler, Claudia Keitel, Naomi Kodama, photosynthetic processes, Gessler et al. investigated the effect of Christopher Weston,Anthony J. Winters, starch storage and remobilisation on the stable carbon isotope Heather Keith, Kliti Grice, Ray Leuning signature in Eucalyptus delegatensis, and the potential carbon isotope fractionation associated with phloem transport and and Graham D. Farquhar 692–706 respiration. The difference in 13C signal observed between transitory starch remobilised during the night and soluble sugars exported during the day corresponds to their hypothesis, and the 13C signal in twig phloem exudates matches the signal in remobilised starch during the night.

Cover illustration: Autumn senescing sugar maple leaves, showing anthocyanin pigments (see van den Berg and Perkins pp. 714–719). Photo by Paula Murakami. Early flowering induction and Agrobacterium The work of Southerton tackles some of the challenges transformation of the hardwood tree species researchers face when studying flowering in eucalypts and the Eucalyptus occidentalis difficulties associated with genetically transformed eucalypts. Simon G. Southerton 707–713 He demonstrates that very early flowering is common in Eucalyptus occidentalis, and that the species is susceptible to Agrobacterium transformation, making it a valuable experimental species for molecular and other flowering studies in the genus.

Contribution of anthocyanins to the antioxidant These authors show that flavonoid (particularly anthocyanin) capacity of juvenile and senescing sugar maple production during leaf development and leaf senescence in sugar (Acer saccharum) leaves maple could provide antioxidant capacity, giving some protection Abby K. van den Berg and Timothy D. Perkins 714–719 against degradation by reactive oxygen species. They also show that anthocyanin production by developing leaves is strongly associated with in vitro antioxidant activity, and deduce that antioxidants other than anthocyanins may be more important.

Impairment of leaf hydraulics in young plants of Citrus Phoma trachephila causes dieback of several Citrus species. aurantium (sour orange) infected by Phoma tracheiphila The impact of this on leaf hydraulics was studied in Fabio Raimondo, Francesco Raudino, Citrus aurantium (sour orange) with the aim of identifying the Santa Olga Cacciola, Sebastiano Salleo primary mechanism of damage to leaves. Leaf infection was and Maria Assunta Lo Gullo 720–729 focused in veins that were first forced to embolise and then invaded by fungal hyphae. The native dominant hydraulic resistance of leaf vasculature in sour orange amplified the impact of vein embolism on leaf water relations, which ultimately led to shedding.

Mycorrhizal effects on growth and nutrition of tomato Cavagnaro et al. investigate the implications of elevated CO2 under elevated atmospheric concentrations on arbuscular mycorrhizal plant interactions. Timothy R. Cavagnaro, Shannon K. Sokolow They compare growth, nutrient contents and mycorrhizal and Louise E. Jackson 730–736 colonisation of a reduced mycorrhizal mutant and its mycorrhizal wild type progenitor under elevated and ambient CO2 concentrations. Although mycorrhizal colonisation was not affected by CO2 concentration, the mycorrhizal plants showed different growth responses. This suggests that the costs and benefits to the plant of forming mycorrhizal associations are altered under elevated CO2.

Microarray analysis of bast fiber producing tissues of Gene expression profiles in phloem fibre-enriched outer tissues Cannabis sativa identifies transcripts associated with in hemp were analysed using microarrays. The authors compare conserved and specialised processes of secondary wall bast samples along the axis of stems, across a developmental development gradient of bast fibre differentiation separating the elongation Mary A. De Pauw, John J. Vidmar, JoAnn Collins, phase with two stages of secondary cell wall biosynthesis. Their Rick A. Bennett and Michael K. Deyholos 737–749 findings extend biochemical models of bast fibre development and secondary wall deposition.

On the role of H2O2 in the recovery of grapevine (Vitis This is the first in-depth study of the physiology and vinifera cv. Prosecco) from Flavescence dorée disease biochemistry of the recovery phenomenon in Flavescence dorée Rita Musetti, Rosita Marabottini, Maurizio Badiani, (FD) phytoplasma-affected grapevines. Little is understood Marta Martini, Luigi Sanità di Toppi, Stefano Borselli, about the physiological processes following recovery from FD Michele Borgo and Ruggero Osler 750–758 disease. The authors found that H2O2 accumulates in grapevines following recovery, when FD phytoplasma could not be detected. They hypothesise that this is associated with a defence response restricting the presence of phytoplasma and, assuming the disease is caused by phytoplasma, results in recovery.