Abstract. The United Nations Food and Agriculture Organisation (FAO) forecasts a 34% increase in the world population by 2050. As a consequence, the productivity of important staple crops such as cereals needs to be boosted by an estimated 43%. This growth in cereal productivity will need to occur in a world with a changing climate, where more frequent weather extremes will impact on grain productivity. Improving cereal productivity will, therefore, not only be a matter of increasing yield potential of current germplasm, but also of improving yield stability through enhanced tolerance to abiotic stresses. Successful reproductive development in cereals is essential for grain productivity and environmental constraints (drought, cold, frost, heat and waterlogging) that are associated with climate change are likely to have severe effects on yield stability of cereal crops. Currently, genetic gains conferring improved abiotic stress tolerance in cereals is hampered by the lack of reliable screening methods, availability of suitable germplasm and poor knowledge about the physiological and molecular underpinnings of abiotic stress tolerance traits.

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The Pleurotus eryngii species-complex includes taxa of the northern hemisphere growing in association with plants of the family Apiaceae (umbellifers). In this study, 45 Pleurotus strains were isolated from five different hostplants: Ferula ovina, F. assa-foetida, Smyrniopsis aucheri, Kellusia odoratissima, and Cachrys ferulacea; all plant species, with the exception of C. ferulacea, are reported for the first time as hosts for this fungal group. Random amplified polymorphic DNA-PCR (RAPD) analysis and nucleotide sequence data from the internal transcribed spacer of the nuclear rRNA genes (ITS1, 5.8S and ITS2) were used for assessing genetic diversity and for determining phylogenetic relationships among the populations studied. Results permitted the grouping of the strains studied into three major clusters corresponding mainly to the nature of the host-plant: the first included isolates collected from Ferula spp. only, the second included isolates originating from C. ferulacea only but from various sampling locations, and the third included all K. odoratissima and S. aucheri associated strains plus a few isolates collected from F. ovina and C. ferulacea. The grouping of the Iranian material, in conjunction with the position in the resulting phylograms of other previously obtained P. eryngii complex sequences, revealed that the first cluster is related to the asiatic 'P. nebrodensis' (or to the asiatic Ferula spp. associated Pleuroti), the second forms a rather distinct lineage which is linked with reference strains originally classified as P. fossulatus, whereas the third cluster falls within the main part (or the "core") of this complex, i.e., P. eryngii. Pleurotus populations growing on umbellifers in Iran seem either to have recently diverged through a sympatric speciation process based mainly on ecological factors (e.g., P. fossulatus), or they form part of a rather wide agglomerate associated with various host-plants where exchange of genetic material is still in progress (i.e., P. eryngii).

Carotenoids, a diverse group of colorful pigments, contribute to the development, light harvesting and photoprotection in plants as well as human health. Due to the interesting properties of carotenoids, enhanced carotenoid biosynthesis has been of ongoing interest. Recent advances in computational biology and bioinformatics make it more feasible to understand the transcriptional regulatory network underlying carotenoid biosynthesis.Studies on carotenoid biosynthesis in corn (Zea mays L.) have indicated the pivotal role of the phytoene synthase gene PSY1 (accession: GRMZM2G300348) in endosperm color and carotenoid accumulation in corn kernels.Computational approaches such as Genomatix, PlantPAN, PlantCARE, PlantTFDB and IGDE6 have been used for promoter prediction, regulatory features and transcription factor identification, as well as pairwise promoter comparisons. Four transcripts have been identified for the PSY1 gene. Based on Genomatix and PlantPAN, the promoter predicted for GRMZM2G300348_T01 was different from that predicted for the other three transcripts (GRMZM2G300348_T02, GRMZM2G300348_T03 and GRMZM2G300348_T04). The results indicated that the promoter of GRMZM2G300348_T01 has more diverse motifs involved in hormonal/environmental stress responses. The most significant result obtained from this study is the discovery of two transcription factors belonging to the HB family that are co-expressed with all four transcripts of PSY1 under environmental stresses. It is, therefore, likely that these transcription factors may act as critical regulators of PSY1 gene expression in corn. Identification of the proteins acting upstream of PSY1 within corn will shed light on the fine tuning of PSY1 expression regulation. Such an understanding would also contribute to metabolic engineering aimed at enhanced carotenoid biosynthesis.