Browsing by Subject "Photoperiod sensitivity"

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Studies on flowering time and photoperiod sensitivity in domesticated and wild amaranth species (Amaranthus spp.)
(2023) Baturaygil, Ali; Schmid, Karl J.
Flowering time plays fundamental roles in the local adaptation and agricultural productivity of the crops. Photoperiodic response regulates the time of flowering by adjusting the response of plant circadian rhythm to environmental signals. Amaranth (Amaranthus spp.) is a short-day crop native to Central and South America, and mainly used as grain and vegetable. Hence, photoperiod sensitivity is a pivotal trait for grain amaranths in Central Europe climatic and long-day conditions, as it determines the local adaptability and the cultivation purpose of the crop i.e., grain or biomass production. However, the knowledge on the different aspects such as breeding, domestication history and adaptation genetics is very limited in grain amaranths. In this project, we studied such different aspects of grain amaranths by addressing the elucidative photoperiod sensitivity trait. In the first study, the phenotypic evaluation of biomass yield components revealed two distinct growth types. Of those, our ten biomass genotypes showed mild to high photoperiod sensitivity, flowered late or completely rejected flowering, reached long final plant heights and low dry matter content. In contrast, the only grain type variety showed photoperiod insensitivity, flowered early, and reached a short final plant height and a relatively higher dry matter content. Our results suggested that selection for both high dry matter yield and content requires a trade-off between photoperiod sensitivity and early flowering, due to the negative correlation between these traits. In the second study, characterization of genebank accessions from the three major grain species (A. caudatus, A. cruentus, A. hypochondriacus) and their wild relative species (A. hybridus and A. quitensis) for adaptive traits such as flowering time and seed setting under long-day conditions discovered a larger photoperiodic variation in the Central American accessions ranging from insensitivity to high sensitivity, whereas South American accessions showed a more narrow variation, limited by mild sensitivity. This result suggests the Central American origin of the wild relative A. hybridus, which might have migrated from Central to South America, and potentially has been selected against high photoperiod sensitivity. Moreover, we studied the environmental variables that may influence seed setting. Photoperiod insensitive accessions set seed regardless of their origin. However, mild photoperiod-sensitive accessions set seed, only if they were from warm center of origin. In the third study, we investigated the genetic architecture of photoperiod sensitivity. The bimodal-like flowering time distributions, and the linkage and association mapping studies using three different populations revealed that photoperiod sensitivity trait is controlled in an oligogenic manner. In particular, all three populations consistently found the same ‘consensus region’ that includes a very promising candidate gene called ‘response regulator of two-component system’. The homologs of this candidate gene are responsible for photoperiodic response in a variety of different crops and the model species Arabidopsis thaliana. In addition, the phenotypic analyses, and the marker data (i) showed photoperiod sensitivity guided pleiotropic relationships between the traits, (ii) revealed a potential epistatic behavior of the genomic region controlling photoperiod sensitivity, and (iii) showed the dominance of photoperiod sensitivity over insensitivity in that region.