Disease relevance of Hypocotyl

• Our results show that TOC1 RNA interference and toc1-2 mutant plants displayed an important reduction in sensitivity to red and far-red light in the control of hypocotyl elongation, whereas increments in TOC1 gene dosage clearly enhanced light sensitivity [1].
• It is demonstrated that overexpression of CRY1 resulted in hypersensitivity to blue, UV-A, and green light for the inhibition of hypocotyl elongation response [2].
• The levels of mRNA for mitochondrial Cpn60 in cotyledons, hooks and hypocotyls of pumpkin seedlings increased in response to heat stress, as deduced from Northern-blot analysis, indicating that pumpkin mitochondrial Cpn60 is a heat-induced stress protein [3].

High impact information on Hypocotyl

• Overexpression of the cytochrome P450 results in enhanced hypocotyl growth even in the light, which phenocopies the etiolated hypocotyls [4].
• The morphology of the hookless hypocotyl is phenocopied by inhibitors of auxin transport or by high levels of endogenous or exogenous auxin [5].
• COP1, when fused to beta-glucuronidase (GUS), is enriched in the nucleus in darkness, but not in the light, in hypocotyl cells of Arabidopsis seedlings and epidermal cells of onion bulbs [6].
• In contrast, seedlings grown in darkness become etiolated, with elongated hypocotyls and dosed cotyledons on an apical hook [7].
• The hy4 mutant is one of several mutants that are selectively insensitive to blue light during the blue-light-dependent inhibition of hypocotyl elongation response, which suggests that they lack an essential component of the cryptochrome-associated light-sensing pathway [8].

Biological context of Hypocotyl

• We describe a new mutant, hfr1 (long hypocotyl in far-red), that exhibits a reduction in seedling responsiveness specifically to continuous far-red light (FRc), thereby suggesting a locus likely to be involved in phytochrome A (phyA) signal transduction [9].
• When expressed from the SHY2 promoter, both shy2-2 and bdl inhibited cell elongation and auxin-induced gene expression in the seedling hypocotyl [10].
• This aberrant phenotype in red light requires functional phyB, suggesting that OBP3 is a positive regulator of phyB-mediated inhibition of hypocotyl elongation [11].
• The sgr2 and zig/sgr4 mutants exhibited abnormal gravitropism in both inflorescence stems and hypocotyls [12].
• In particular, the extra endoreplication cycle that occurs in dark-grown hypocotyl cells is associated with upregulation of the AtCDC6 gene [13].

Anatomical context of Hypocotyl

• The blue light-induced destabilization response persists in long hypocotyl hy4 and phytochrome phyA, phyB, and hy1 mutants as well as in far-red light-grown seedlings, indicating that neither CRY1 (encoded by the hy4 locus) nor phytochrome is the sole photoreceptor [14].
• Microtubule density was indistinguishable from that of the wild type, but microtubule organization was affected in trichomes and hypocotyl cells of dark-grown kis plants [15].
• A step-like transition believed to be glass transition was observed in walls isolated from the elongating region of soybean hypocotyls at 52.9 degrees C. Addition of 1 mM CaCl2 to the cell wall preparation increased the transition temperature to 60.8 degrees C and greatly reduced the transition magnitude [16].
• Chalcone synthase [naringenin-chalcone synthase; malonyl-CoA:4-coumaroyl-CoA malonyltransferase (cyclizing), E.C. 2.3.1.74], the key enzyme of flavonoid pathways that was believed to be soluble, has been localized on ribosome-bearing endoplasmic reticulum membranes in the epidermis of buckwheat (Fagopyrum esculentum M.) hypocotyls [17].
• Confirmation of the presence of a beta-type adaptin in plants was provided by dot and Southern blotting experiments using genomic DNA from zucchini hypocotyls and a beta-adaptin cDNA clone from human fibroblasts [18].

Associations of Hypocotyl with chemical compounds

• Among plant growth factors involved in the control of hypocotyl elongation (auxin, gibberellins and ethylene) none significantly influenced KOR-mRNA levels [19].
• SAc3 and SAc7 genes appear to be more highly expressed in shoot and 2,4-dichlorophenoxyacetic acid-induced hypocotyl than in root and hypocotyl.(ABSTRACT TRUNCATED AT 250 WORDS)[20]
• In wild-type seedlings, sucrose repressed the far-red light-induced cotyledon opening and inhibition of hypocotyl elongation. sun7 seedlings showed reduced repression of these responses [21].
• Studies with PHO1 promoter-beta-glucuronidase constructs reveal predominant expression of the PHO1 promoter in the stelar cells of the root and the lower part of the hypocotyl [22].
• This mutant exhibited hypersensitive induction of CAB1, CAB2, and the small subunit of ribulose-1,5-bisphosphate carboxylase (RBCS) promoters in the very low fluence range of red light and a hypersensitive response in hypocotyl growth in continuous red light of higher fluences [23].

Gene context of Hypocotyl

• We show that FHY1 is a novel light-regulated protein that accumulates in dark (D)-grown but not in FR-grown hypocotyl cells [24].
• However, phenotypic analysis of transgenic seedlings suggested that the constitutively nuclear-localized WD-40 repeat domain was able to mimic aspects of COP1 function, as indicated by exaggerated hypocotyl elongation under light conditions [25].
• Long Hypocotyl in Far-Red 1 (HFR1), a basic helix-loop-helix transcription factor, is required for both phytochrome A-mediated far-red and cryptochrome 1-mediated blue light signaling [26].
• The blue light receptor NPH1 (for nonphototropic hypocotyl) has been considered to be the only UV-A/blue light receptor that induces a phototropic response by the hypocotyl and root of Arabidopsis [27].
• Gain-of-function mutations in SHY2/IAA3 cause enlarged cotyledons, short hypocotyls, and altered auxin-regulated root development [28].

Analytical, diagnostic and therapeutic context of Hypocotyl

• Complementation tests with various long hypocotyl (hy) mutants indicated that CR88 identifies a new HY locus [29].
• The auxin-regulated expression of two poly(A)+ mRNAs in soybean hypocotyl was demonstrated by cloning of the cDNAs and Northern blot hybridization analyses (Walker, J.C., and Key, J.L. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 7185-7189) [30].
• Stomata formation in the hypocotyl is induced by the treatment with either GA or ethylene [31].
• The measurements of melatonin and IAA in lupin hypocotyls by high-performance liquid chromatography with electrochemical detection, and their identification by tandem mass spectrometry, point to a different distribution of these molecules in etiolated hypocotyls [32].
• The expression of a maturation-associated gene, Mat1, was induced in both cotyledons and hypocotyl/radicle tissues of somatic embryos after 72 h desiccation [33].

References