Abstract
Seasonal dormancy is an adaptive mechanism where plants suspend growth and become physiologically inactive to avoid extreme environmental conditions. Environmental factors like temperature, photoperiod, nutrients, and soil moisture control plant growth and development through various complex molecular mechanisms. Crown and seed dormancy of plants are mostly influenced by day length and temperature. Genes and physiological pathways triggered by these two factors along with genotype variability are some targets to manipulate seasonal dormancy. There is genetic variation in the depth and duration of seasonal dormancy. Therefore, their genetic manipulation is possible. Manipulations of summer and fall dormancy are relatively easier compared to winter dormancy because plants require protection of their apical meristem from freezing temperatures and limited water supply. Genetic factors that regulate seed dormancy may also have regulatory role for seasonal dormancy of the maternal plants. Limited genetic and genomic information are available for seasonal dormancy in herbaceous perennial species. Knowledge of genes controlling seasonal dormancy of eudicots, forest trees, and horticultural crops could be interpolated to explore possible dormancy mechanisms in perennial forages. This study reviews current knowledge of seasonal dormancy of herbaceous forages emphasizing the genetic and physiological context that would be valuable to breeders and plant biologists to expand the production season of perennial species by developing non-dormant and semi-dormant cultivars.
Highlights
Herbaceous forage grasses and legumes are the cornerstone of feed resources for livestock and food security globally [1]
Ding and Missaoui (2017) confirmed CONSTANS and TERMINAL FLOWER (TFL), dormancy-associated MADS-box (DAM), auxin response factors (ARFs) and heat shock proteins (HSPs) as potential candidate genes involved in the control of tall fescue summer dormancy (Table 2) [83]
Seasonal dormancy in herbaceous perennial grasses and legumes is an adaptive mechanism to survive in harsh environments
Summary
Herbaceous forage grasses and legumes are the cornerstone of feed resources for livestock and food security globally [1]. Forage crops are either grazed directly on pasture or transported as hay, silage, green-chop, and pellets [4] Forage species include both annual and perennial species and are categorized into cool season and warm season based on their primary growth period and availability [5]. Warm-season crops exhibit C4 carbon fixation pathway and are efficient in fixing atmospheric carbon dioxide These grasses are excellent alternative forage sources in summer when cool season grasses are not abundant [7]. We provide insights into the possible genetic and genomic factors controlling seasonal dormancy of vegetative buds and seeds of common herbaceous species with focus on the roles of photoperiod and temperature in controlling such traits. We compile published information on genes and genomic features of some eudicots that could be extrapolated to infer the underlying molecular basis of grass seasonal dormancy
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