SummaryUnderstanding the development of the cereal caryopsis holds the future for metabolic engineering in the interests of enhancing global food production. We have developed a Serial Analysis of Gene Expression (SAGE) data platform to investigate the developing wheat has also provided a resource of novel sequence and expression information including the identification of potentially useful promoter activities. Further investigations into both the abundant and low expressing transcripts will provide greater insight into wheat caryopsis development and assist in wheat improvement programmes.

Seedlings of Eucalyptus camaldulensis, E. comitae-vallis, E. kondininensis, E. lesouefii, E. platycorys, E. spathulata and Casuarina obesa were grown in a glasshouse under non-saline drained, saline drained, non-saline waterlogged, and saline waterlogged conditions for 3 months. Measurements were taken of seedling height, seedling survival and the concentration of Na, K, Ca, Mg and Cl in plant tissues. Production of specialised roots containing aerenchyma in E. camaldulensis and C. obesa enabled these species to tolerate non-saline waterlogged conditions. Saline, but freely drained conditions reduced seedling growth for all species but only E. kondininensis recorded seedling deaths. C. obesa was the species most tolerant of saline waterlogged conditions with no seedling deaths and a lower reduction in growth compared to the Eucalyptus species. Exclusion of Na and Cl, together with the production of specialised roots by C. obesa are suggested as the probable factors relating to the high seedling tolerance in saline waterlogging. The species with highest tolerance to non-saline waterlogging were more tolerant of saline waterlogged conditions. The importance of this result for evaluating trees to be used in the rehabilitation of secondary salinised land in Australia is discussed.

A cDNA library containing approximately 5,000 clones from germinating barley embryos was constructed and used to examine the variation in gene expression patterns during the first 4 days postimbibition. The expression profiles of embryos (including scutellum) from 4 to 96 h postimbibition were compared to a reference profile from 24 h postimbibition using microarray analysis. A subset of clones exhibiting tenfold or greater differential expression patterns was sequenced to elucidate function. All of the sequenced clones could be identified to at least EST level with 64% exhibiting homology to published protein sequences. Almost 95% of the library exhibited similar expression levels at the 4 h time point as at the 24 h reference point. From 24 to 96 h, however, considerable fluctuations in gene expression occurred. The observed patterns of gene expression for the classified genes are consistent with the expected genetic changes required to prepare an embryo for germinative development. A replicate set of clones for the 23-kDa jasmonate-induced protein was identified. The current data not only provides conclusive evidence for the expression patterns of this abundant stress-response protein in germinating embryos, but also serves to validate previous research into JIP-23 isoforms, function and the relationship between timing of mRNA upregulation and protein abundance.

The effects of salinity and waterlogging on stomatal conductance, net photosynthesis and transpiration of 3-month-old Eucalyptus camaldulensis Dehnh. and Eucalyptus lesouefii Maiden seedlings were studied under greenhouse conditions. Under non-saline conditions, waterlogging induced stomatal closure in both species. However, the stomata of E. camaldulensis reopened after five weeks, when adventitious roots were produced. Relative to that of controls, height growth of waterlogged seedlings was greater in E. camaldulensis than in E. lesouefii, as were rates of photosynthesis and transpiration. In a freely drained medium, high salinity reduced rates of seedling height growth and photosynthesis, relative to those in controls, less in E. lesouefii than in E. camaldulensis. In both species, height growth, stomatal conductance and photosynthetic rate were lowest under conditions of saline waterlogging.