Aerenchyma formation in the initial development of maize roots under waterlogging

We investigated the role of antioxidant and cell wall loosening enzymes in aerenchyma formation in roots of Saracura maize (Zea mays) from two different selection cycles with contrasting tolerance to waterlogging. Plantlets of Saracura maize from the 1st cycle (C1—sensitive) and 18th cycle (C18—tolerant) of selection were subjected to waterlogging for 0, 24, 48, 72, 96, and 120 h, and roots were collected for biochemical and anatomical analyses. Plantlets of cycle 18 exhibited higher aerenchyma formation, exodermis thickening, and higher activity of alcohol dehydrogenase, polygalacturonase, cellulase, and antioxidant enzymes than plantlets of cycle 1. Although these processes also occurred in C1 plantlets, they were independent of the waterlogging and therefore were initiated later. C18 plantlets exhibited biochemical and physiological characteristics that may have contributed to the higher water excess tolerance of Saracura maize plantlets from the later selection cycle. Higher aerenchyma formation in C18 plantlets is related to higher and early activity of cell wall loosening enzymes and higher activity of antioxidant enzymes than in C1 plantlets.