Maize mutants

N. von Wiren, S. Mori, H. Marschner, and V. Romheld, Iron inefficiency in maize mutant ysl Zea mays L. cv. Yellow-stripe) is caused by a defect in uptake of iron phytosiderophores. Plant Physiol. 106 1 (1994). 

The results in Table I show that, in the presence of plant material, the standard GA3 is spread over a considerably wider range than is usual. However, after the sample is further purified by the second run, the mobility of GA3 returns to normal. The same pattern of distribution, with zone III as maximum, is manifest in the natural run, although at considerably lower fluorescent intensities. For both fractions, the presence of GA3 is confirmed by the capryl system. A portion of zone III of the natural extract gave positive response proportional to concentration in the pinto bean seedling assay and in the dwarf maize mutants I and V assay. The relative activity on both mutants was approximately equal, as is required for GA3 (26). The correlation of relatively specific biological growth activity with chromatographic and chemical behavior affirms the presence of a GA3-like substance in kudzu vine. 

Figure 1. Standard curve showing response of first internode of d5 maize mutant to applied gtbberellin As...

Figure 2. Relation between sprouting of Red Pontiac potato tubers (A) and level of endogenous gibberellins in potato peels and buds during and after rest (C) as measured by internode elongation of maize mutant d5( B)...

Figure 3. Gibberellin-like activity in peels of Red Pontiac potatoes during and after rest as revealed by intemoae elongation of maize mutants 1,3, and 5...

Figure 4. Histogram of extracts from young leaves of vegetative and photoinduced plants of Hyoscyamus niger, tested on d-1, a-3, and d-5 maize mutants (23)...

The inhibitory properties of the four filtrates and the four eluates were determined by bioassay with the dwarf-1 maize mutant (Table II). Only the first eluate was inhibitory, the next three showing little if any reduction in leaf-sheath length. In contrast, all filtrates were inhibitory. Since the initial. treatment with charcoal and Celite removed only some inhibitory material while subsequent treatments left the remaining inhibitory material in the supernatant, there must be at least two inhibitory materials in the extract, only one of which is adsorbed by charcoal. 

Maize mutants with altered flavonoid metabolism can also be identified based on variation in color, either of the seeds, the vegetative parts of the plant, or the floral structures (anthers and silks). Petunia (Petunia hybrida) and snapdragon (Antirrhinum majus) have also been widely used as model species for the elucidation of flavonoid biosynthesis (reviewed by Winkel-Shirley, 2001). In the description of genes involved in flavonoid biosynthesis presented in this section, the emphasis will be on maize and Arabidopsis. 

Tsai, C. Y., and Nelson, O. E. 1966. Starch-deficient maize mutant lacking adenosine diphosphate glucose pyrophosphorylase activity. Science 151, 341-343. 

One additional line of evidence that independently implicates a 32 kDal polypeptide in triazine binding comes from studies on chloroplasts isolated from a maize mutant that specifically lacks the stainable 32 kDal polypeptide and the rapidly labeled 34 kDal polypeptide. Chloroplasts of this PS Il-less lethal mutant lack binding sites for radioactive atrazine (35). 

Recent studies in our laboratory have indicated that the cytochrome hjf cyVhJT) complex is involved in the light induced phosphorylation of LHQI polypeptides in Acetabularia mdLemna (1,2). Similar data have been obtained with several cyt.be/f deficient Chlamydomonas (3) and maize mutants (4,5). To furtho ascertain that indeed the cyth /f complex is required for the activation of the redox controlled LHC n kinase, the activity of this enzyme(s) was assayed in another Chlamydomonas mutant lacking the complex components. 

Acetyl-coenzyme A carboxylase (ACCase) carboxylates acetyl-coenzyme A to malonyl-coenzyme A which serves as an intermediate metabolite for several diverse pathways in plant metabolism including synthesis of fatty acids, flavonoids, pigments and waxes. Plants likely have more than one ACCase isoform -- one in the plastid for fatty acid synthesis and at least one non-plastidic form to provide malonyl-coenzyme A for the other pathways. In maize, the plastid-localized ACCase required for fatty acid synthesis has been identified as a target site for several herbicide families [1] and herbicide-tolerant maize mutants have been selected [2,3]. 

Waxy maize Mutant type of corn that contains more than 95% amylopectin in the starch. It is wet-milled to obtain waxy starch, which has special uses. Waxy starch has a higher hot paste viscosity and produces softer and clearer gels than regular starch. 

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