Differential and interactive effects of cytoplasmic substitution and seed ageing on submergence stress response in wheat (Triticum aestivum L.)

Abstract

Cytoplasmic genomes affect various phenotypes, including abiotic stress responses, through interaction with nuclear genomes in plants. We focused on the effects of cytoplasmic substitution on germination and seedling growth in combinations with submergence and seed ageing, both of which are known to inhibit these traits posing a challenge in agriculture and seed banking. We carried out comparative phenotypic studies of submergence and seed ageing effects using a series of nucleus-cytoplasm (NC) hybrids of wheat, in which 11 heterologous cytoplasms of Triticum and Aegilops species were combined with a common nucleus. Adopting the testtube bioassay, germination and seedling growth were studied using aged and non-aged seeds. Imbibed seeds were subjected to 3-days submergence followed by incubation under de-submergence conditions. Seed ageing reduced the germination rates in NC hybrids. Submergence and seed ageing both caused reduction of seedling growth evaluated by shoot length in all or most of the lines. The magnitude of shoot growth inhibition by submergence and seed ageing varied greatly among NC hybrids compared with the nuclear donor, and three distinct response types were recognized. Submergence and seed ageing, in combination, caused leaf chlorosis in most of NC hybrids. Our results suggested that the observed diverse effects of cytoplasmic substitution were exerted through differential interactions with submergence and seed ageing. Further studies are needed to clarify the mechanisms underlying cytoplasmic genome diversity and interaction with nuclear genomes affecting submergence and seed ageing responses in wheat. ARTICLE HISTORY

Nucleus-cytoplasm compatibility: A genetic system underlying allopolyploid speciation as exemplified in alloplasmic lines of wheat

“…Submergence stress markedly increased superoxide dismutase (SOD) activity in the susceptible hybrids, suggesting that the elevated SOD activity has resulted from high levels of accumulated reactive oxygen species. Comparative studies of submergence and the effects of seed aging on germination and seedling growth were also made using hexaploid wheat NC hybrids (Takenaka et al 2019). Magnitudes of inhibition of shoot growth by submergence stress and seed aging varied greatly among NC hybrids, and their combination caused severe leaf chlorosis in most hybrids.…”