Genetic dissection of abscisic acid biosynthesis in maise embryos /
Carotene and xanthophyll levels were determined in embryos of wild-type and viviparous mutants of Zea mays L. vp2 and vp5 accumulated phytoene, w3 phytofluene, and vp9 accumulated C-carotene. VP an vp5 accumulated phytoene, w3 accumulated phytofluene, and vp9 accumulated x-carotene. The terminal car...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739363511&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Carotene and xanthophyll levels were determined in embryos of wild-type and viviparous mutants of Zea mays L. vp2 and vp5 accumulated phytoene, w3 phytofluene, and vp9 accumulated C-carotene. VP an vp5 accumulated phytoene, w3 accumulated phytofluene, and vp9 accumulated x-carotene. The terminal carotenoid of vp7 accumulated g-carotene. However e-carotene, a product of d-carotene in some plants, has not carotenoid of vp7 been found in maize. It appears that g-carotene is the sole precursor of both b-carotene and a-carotene. Lutein reduced from 27% of total xanthophyll to 2% in embryos of vp8 by removing plumules. The relative amount of lutein in embryos of wild-type was also 2%. Lutein was produced mainly in the elongated shoots of viviparous mutants. Lutein epoxide and 9-cis-lutein epoxide, possible products of lutein, were not detected in mutant and wildtype embryos. It appears that lutein is not a precursor of ABA. The accumulation of zeaxanthin combined with the reduction of epoxy-xanthophylls gives an indication of the genetic lesion site of vplo and vplo-like mutants. The mutation impairs the epoxidation of zeaxanthin. Accumulation of violaxanthin, neoxanthin and 9-cisneoxanthin combined with the reduction of zeaxanthin was shown in vp8 and vp8-like mutants. The mutation probably affects an oxidative cleavage step. it is also possible that it affects the conversion of xanthoxin to ABA-aldehyde. The vp-92EPB accumulated violaxanthin. The vp-92GN24 and vp-90GS8 accumulated violaxanthin and neoxanthin it appears that neoxanthin is the intermediate between violaxanthin and 19-cis-neoxanthin. The vp-92EP8 affects the conversion of violaxanthin to neoxanthin. The vp-92GN24 and vp-90GS8 affect the conversion of neoxanthin to 19-cis neoxanthin.The xanthophyll intermediates of ABA biosynthesis in embryos are identical to those in leaves. This study also supports claims for a universal ABA biosynthetic pathway. |
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| Item Description: | Vita. "Major Subject: Genetics". |
| Physical Description: | x, 68 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 57-67. |