Phenotypic and genotypic characterization of an amylose-free starch mutant of the potato

Abstract

The amylose-free (amf) potato mutant 86 .040 has been characterized phenotypically and genotypically . Not only storage starch in tubers and metabolic starch in leaves but also starch in cells with specific functions, such as columella cells in the root cap and guard cells of stomata, was amylose-free . Doubled amf-clones of 86 .040 flowered well, but the percentage of stainable pollen was low (8 .2%) . Therefore, they were used as female parent in crosses with diploid amylose-containing plants . Over 1400 pollinations gave 13 berries, all dropping off prematurely ; they contained 78 ovules with embryos at different developmental stages . Twenty Ft plants were obtained by embryo rescue, all having amylose starch . Three of them were characterized more extensively . They flowered well, and pollen stainabilitity as well as seed set were high . Analysis of the F, plants and of F, X F, progeny plants showed that the amf-character is monogenic and recessive . The locus involved was designated amf+ and the mutated allele amf.

Expression of poly-3-(R)-hydroxyalkanoate (PHA) polymerase and acyl-CoA-transacylase in plastids of transgenic potato leads to the synthesis of a hydrophobic polymer, presumably medium-chain-length PHAs

“…In vitro-grown Solanum tuberosum L., genotype 1024-2 (amf, diploid; Jacobsen et al 1989-Laboratory of Plant Breeding, Wageningen University & Research Centre, Wageningen) was used as starting material for particle bombardment-mediated co-transformation as described elsewhere (Romano et al 2001(Romano et al , 2003a(Romano et al , 2003c DNA polymerase] from genomic DNA of P. putida KT2442. Primers 5¢-CCATGGGGCCAGAAATCG-CTGTACTTG-3¢ and 5¢-CGGGATCCTCAGATGG-CAAATGCATGC-3¢ were used, which introduced, by primer extension, NcoI and BamHI restriction sites at the 5¢ and 3¢ ends of the gene, respectively.…”

Wheat Granule-Bound Starch Synthase I and II Are Encoded by Separate Genes That Are Expressed in Different Tissues

“…The presence of blueblack-staining starch containing amylose in non-storage organs of waxy mutants has been reported in both maize (Hixon and Brimhall, 1968;Badenhuizen, 1969) and rice (Sano, 1985); therefore, the presence of genes related to GBSSII in these species is not surprising. In potato, a single GBSSI appears to be responsible for the presence of amylose in tuber, leaf, root, and pollen starch (Jacobsen et al, 1989), but at least two isoforms occur in pea (Denyer et al, 1997;Tomlinson et al, 1998). However, although wheat GBSSII showed closer homology to GBSSI from pea and potato than to GBSSI from wheat at both the nucleotide and amino acid levels, neither wheat GBSSI nor GBSSII produced clear bands with the dicotyledonous species pea, potato, tomato, soybean, or taro.…”

Starch biosynthesis.

“…However, the amylose that they produce in vivo is somehow protected from the activity of SBEs in the plastid, even though SBEs can use it as a substrate in vitro. The key to understanding the synthesis of these discrete products lies in the discovery that wx mutants of maize, rice, sorghum, and Amaranthus, and the amy/ose free (amf) mutant of potato, make no amylose and lack the activity of an exclusively GBSS (GBSSI; Sprague et al, 1943;Nelson and Rines, 1962;Tsai, 1974;Okuno and Sakaguchi, 1982;Sano, 1984;Hseih, 1988;Jacobsen et al, 1989) that has also been frequently referred to as the "waxy" protein. This -60-kD protein is made in relatively large amounts and is found exclusively bound to the starch granule.…”