ISOLATION AND CHARACTERIZATION OF A TOBACCO CDNA CLONE ENCODING A PUTATIVE MAP KINASE

We have isolated and sequenced a MAP (mitogen-activated protein) kinase-type cDNA from a tobacco (Nicotiana tabacum L.) cell suspension cDNA library by screening with a PCR fragment amplified from the same library with oligonucleotide primers corresponding to two sequences conserved in yeast and animal MAP kinases. The tobacco sequence, ntf3, shows 45-54% identity to various members of the MAP kinase family at the protein level. Northern experiments showed that ntf3 is expressed in all tobacco tissues tested, including pollen isolated at different developmental stages. Southern analysis indicated that, as in other organisms, there is a family of MAP kinase genes in tobacco. In complementary tests, ntf3 could not substitute the yeast MAP kinase genes fus3 and kss1

A mediterranean japonica rice (Oryza sativa) cultivar improvement through anther culture.

Certified seed producers systematically select and propagate registered varieties year after year in order to maintain their uniformity and the original registered cultivar traits. However, natural mutations, spontaneous breeding between varieties and alien grain contamination can introduce undesir- able variability. NRVC 980385 is a temperate japonica rice cultivar (Oryza sativa ssp. japonica) first regis- tered in Spain in 2002. In 2005 certification tests detected a plot differing from the original traits in terms of uniformity and height suggesting the pres- ence of a certain heterozygosis. This material was therefore seen as an opportunity to obtain newly stabilized doubled haploid (DH) lines which could compete in the Spanish short grain seed market. In this study, an in vitro anther culture protocol is defined which also covers the field tests selection to obtain four new, improved and stabilized DH derived lines ready to be registered for commercial proposes. This took just 4 years from the initial anther collection until new lines were grown in large scale field trials. Consequently, this protocol reduces the time for obtaining field assessed DH lines thereby having considerable advantages over other techniques by both maintaining the original registered cultivars and/or generating new derived varieties