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Shade delays flowering in Medicago sativa
Author(s) -
Lorenzo Christian D.,
Alonso Iserte Javier,
Sanchez Lamas Maximiliano,
Antonietti Mariana Sofia,
Garcia Gagliardi Pedro,
Hernando Carlos E.,
Dezar Carlos Alberto A.,
Vazquez Martin,
Casal Jorge J.,
Yanovsky Marcelo J.,
Cerdán Pablo D.
Publication year - 2019
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14333
Subject(s) - medicago sativa , biology , petiole (insect anatomy) , perennial plant , arabidopsis , medicago , shade avoidance , botany , limiting , forage , arabidopsis thaliana , agronomy , horticulture , gene , genetics , mechanical engineering , hymenoptera , mutant , engineering
Summary Shade‐intolerant plants respond to the decrease in the red (R) to far‐red (FR) light ratio (R:FR) occurring under shade by elongating stems and petioles and by re‐positioning leaves, in a race to outcompete neighbors for the sunlight resource. In some annual species, the shade avoidance syndrome (SAS) is accompanied by the early induction of flowering. Anticipated flowering is viewed as a strategy to set seeds before the resources become severely limiting. Little is known about the molecular mechanisms of SAS in perennial forage crops like alfalfa ( Medicago sativa ). To study SAS in alfalfa, we exposed alfalfa plants to simulated shade by supplementing with FR light. Low R:FR light produced a classical SAS, with increased internode and petiole lengths, but unexpectedly also with delayed flowering. To understand the molecular mechanisms involved in uncoupling SAS from early flowering, we used a transcriptomic approach. The SAS is likely to be mediated by increased expression of msPIF3 and msHB2 in low R:FR light. Constitutive expression of these genes in Arabidopsis led to SAS, including early flowering, strongly suggesting that their roles are conserved. Delayed flowering was likely to be mediated by the downregulation of msSPL3 , which promotes flowering in both Arabidopsis and alfalfa. Shade‐delayed flowering in alfalfa may be important to extend the vegetative phase under suboptimal light conditions, and thus assure the accumulation of reserves necessary to resume growth after the next season.