The identification and characterization of seedlings hyper-responsive to light 2 (SHL2), a gene implicated in developmental responses to light
Year: 2007
Type: dissertation
Abstract: Mutants showing developmental hyper-responsiveness to limited light were screened and\ndesignated as seedlings hyper-responsive to light (shl). These mutants showed an\netiolated phenotype similar to wild type in the dark, yet had shorter hypocotyls, larger\ncotyledons, and more advanced development of true leaves than wild type in low light.\nThe SHL genes act (genetically) as light-dependent negative regulators of\nphotomorphogenesis, possibly in a downstream signaling or developmental pathway that\nis shared by the major photoreceptor genes (CRY1, PHYA, and PHYB) and other\nphotoreceptors (CRY2, PHYC, PHYD, and PHYE). shl1 and shl2 were shown to be\npartially dependent on HY5 activity for their light-hyperresponsive phenotypes.\nshl1-1 showed a defect in responding to auxin in its root development in both white and\nyellow light conditions, and showed a defect in responding to auxin in hypocotyl\nelongation in yellow light. Compared to wild type, both shl1-1 and shl2-2 showed\nincreased hypocotyl length in response to cytokinin in white light. Gibberellin (GA)\npartially recovered shl1-1 mutant phenotype in yellow light, whereas showed no effect\non hypocotyl elongation of shl2-2 in this light condition. These altered responses of\nshl1-1 and shl2-2 to multiple phytohormones in different light regimes suggests that\ncross-talks among light and hormones regulate SHL1 and SHL2. One of the SHL genes, SHL2 was cloned by map-based positional cloning and shown to\nbe allelic to the previously identified locus designated murus3(mur3) and\nkatamari1(kam1). MUR3/KAM1 encodes a XyG galactosyltransferase. Sequence analysis\ndemonstrated that our original EMS generated reference allele shl2-2 is probably not a\nnull mutant, therefore the phenotypes of T-DNA insertion null mutant in SHL2,\nSALK_074435 were studied in different light conditions. Unlike shl2-2, SALK_074435\nhad a slightly short hypocotyl phenotype in the dark (though not to the extent of the\ndet/cop/fus mutants). A consideration of the phenotypes and molecular lesions of shl2-2\nand mur3 alleles, along with the phenotypes of null alleles kam1 and SALK_74435,\nsuggests that SHL2/MUR3/KAM1 may be involved in hypocotyl elongation in low light\nthrough the modification of xyloglucan in the plant cell wall, and may play a role in\nhypocotyl elongation in the dark through proper organization of the endomembrane.
Author: Mi-Seon Seong
Language: English
Topic: Light effects on plants
Subfield: Plant Science
Domain: Life Sciences
Open Access status: green
Funder: McKnight Foundation
OpenAlex ID: W2291095897