Distinct mechanisms for aerenchyma formation in leaf sheaths of XXXX genotypes displaying a quiescence or escape strategy for flooding tolerance.

@entity101 @entity26 @entity273 @entity579 @entity1786
BACKGROUND AND AIMS: @entity579 is one of the few crops able to withstand periods of partial or even complete submergence. One of the adaptive traits of @entity579 is the constitutive presence and further development of aerenchyma which enables @entity26 to be transported to submerged organs. The development of lysigenous aerenchyma is promoted by @entity1786 accumulating within the submerged plant tissues, although other signalling mechanisms may also co-exist. In this study, aerenchyma development was analysed in two @entity579 ( @entity579 ) varieties, 'FR13A' and 'Arborio Precoce', which show opposite traits in flooding response in terms of internode elongation and survival. METHODS: The growth and survival of @entity579 varieties under submergence was investigated in the leaf sheath of 'FR13A' and 'Arborio Precoce'. The possible involvement of @entity1786 and reactive @entity26 species (ROS) was evaluated in relation to aerenchyma formation. Cell viability and DNA fragmentation were determined by FDA/FM4-64 staining and TUNEL assay, respectively. @entity1786 production was monitored by gas chromatography and by analysing ACO gene expression. ROS production was measured by using Amplex Red assay kit and the fluorescent dye DCFH(2)-DA. The expression of APX1 was also evaluated. AVG and DPI solutions were used to test the effect of inhibiting @entity1786 biosynthesis and ROS production, respectively. KEY RESULTS: Both the varieties displayed constitutive lysigenous aerenchyma formation, which was further enhanced when submerged. 'Arborio Precoce', which is characterized by fast elongation when submerged, showed active @entity1786 biosynthetic machinery associated with increased aerenchymatous areas. 'FR13A', which harbours the Sub1A gene that limits growth during @entity26 deprivation, did not show any increase in @entity1786 production after submersion but still displayed @entity101 . @entity273 levels increased in 'FR13A' but not in 'Arborio Precoce'. CONCLUSIONS: While @entity1786 controls aerenchyma formation in the fast-elongating 'Arborio Precoce' variety, in 'FR13A' ROS accumulation plays an important role.
