Summary• To adapt to waterlogging in soil, some gramineous plants, such as maize (Zea mays), form lysigenous aerenchyma in the root cortex. Ethylene, which is accumulated during waterlogging, promotes aerenchyma formation. However, the molecular mechanism of aerenchyma formation is not understood.• The aim of this study was to identify aerenchyma formation-associated genes expressed in maize roots as a basis for understanding the molecular mechanism of aerenchyma formation. Maize plants were grown under waterlogged conditions, with or without pretreatment with an ethylene perception inhibitor 1-methylcyclopropene (1-MCP), or under aerobic conditions. Cortical cells were isolated by laser microdissection and their mRNA levels were examined with a microarray.• The microarray analysis revealed 575 genes in the cortical cells, whose expression was either up-regulated or down-regulated under waterlogged conditions and whose induction or repression was suppressed by pretreatment with 1-MCP.• The differentially expressed genes included genes related to the generation or scavenging of reactive oxygen species, Ca 2+ signaling, and cell wall loosening and degradation. The results of this study should lead to a better understanding of the mechanism of root lysigenous aerenchyma formation.

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Several genes related to cell wall modification and proteolysis are specifically up- or downregulated in cortical cells during lysigenous aerenchyma formation under aerobic conditions with ethylene treatment. The results suggest that ethylene is perceived in stelar cells, cortical cells and outer cell layers in the maize primary root, and that the cortical cell-specific PCD is controlled downstream of ethylene perception through subsequent gene expression, which is partly regulated by ROS, in the cortical cells.

Terpenes play a key part in the metabolic processes of a wide variety of animals, plants and microorganisms in which they are produced. In nature, terpenoids serve a variety of purposes including defense, signaling and as key agents in metabolic processes. Terpenes have been used in perfumery, cosmetics and medicine for thousands of years and are still extracted from natural sources for these uses. Terpenes antioxidant activities may sometimes explain their capacity to adjust inflammation, immunological effects and neural signal transmission. They offer pertinent protection under oxidative stress situations including renal, liver, cancer, cardiovascular diseases, neurodegenerative and diabetes as well as in ageing mechanisms.

In this study, we examined the behavior of six faba bean (Vicia faba L.) genotypes under salinity conditions at the seedling stage. The evaluation was assessed using 21 morphological, physiological, and photosynthetic traits under control, moderate, and severe salinity conditions. The principal component analysis (PCA) was used to identify genotypes of contrasting behavior in response to salt stress and to characterize the important traits for salt tolerance. The result of PCA analysis showed that the genotypes displayed different behavior under the saline conditions. The most discriminating quantitative characters were related to plant biomass production and photosynthesis, especially the mass of fresh root, number of leaves, water-use efficiency, and the substomatal CO2 concentration. The analysis of all parameters by PCA permits us to distinguish cv. Najeh as the most tolerant genotype for salinity conditions and cv. Chourouk as the most sensitive one. These results would be of pertinent tools in faba bean breeding programs.

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