Inducible hypertrophied lenticels compensate for insufficient aeration pathways and hydrophobic barrier limitations conferring tolerance to waterlogging stress in cotton (Gossypium hirsutum L.)

To adapt to low-oxygen environments, plants develop aerated tissues and hydrophobic barriers that facilitate internal respiration while protecting against radial oxygen loss (ROL). In plants exhibiting lenticel structures, reduced oxygen levels induce hypertrophy as a compensatory mechanism for oxygen deficiency and enhanced hydrophobic tolerance. However, the physiological mechanisms underlying the aeration and hydrophobic tolerance of inducible hypertrophied lenticels (Hpls) in cotton remain poorly understood. In this study, cotton lenticels were examined following exposure to continuous waterlogging for 10 and 20 days. Tolerant genotypes demonstrated an increase in Hpl formation and adventitious root development (AR), together with improved tolerance to 20 days of waterlogging stress. The Hpl regions exhibited induced thickening of cell wall and xylem tissue. Within the endodermal cells of Hpl, there was notable accumulation of extracellular vesicular tubular structures (EVBs), lignin, suberin, and casparian bands. Furthermore, the Hpl regions facilitated the formation of adventitious roots as well as internal aerated tissues characterized by cortical and arenchymatous phellem (AP). The development of secondary aerated tissues combined with the accumulation of hydrophobic polymers indicates that inducible Hpl plays a dual role in improving waterlogging tolerance. • Inducible hypertrophied lenticel enhanced survival under low oxygen. • Hypertrophied regions enable aeration through adventitious root formation and aerenchyma. • Waterlogging induced hypertrophied regions caused cell and xylem wall thickening. • Hypertrophied regions accumulate hydrophobic polymers to promote tolerance.