Auxin and heat shock activation of a novel member of the calmodulin like domain protein kinase gene family in cultured alfalfa cells.

A calmodulin like domain protein kinase (CPK) homologue was identified in alfalfa and termed MsCPK3. The full-length sequence of cDNA encoded a 535 amino acid polypeptide with a molecular weight of 60.2 kDa. The deduced amino acid sequence showed all the conserved motifs that define other members of this kinase family, such as serine-threonine kinase domain, a junction region and four potential Ca2+ -binding EF sites. The recombinant MsCPK3 protein purified from E. coli was activated by Ca2+ and inhibited by calmodulin antagonist (W-7) in in vitro phosphorylation assays. The expression of MsCPK3 gene increased in the early phase of the 2,4-D induced alfalfa somatic embryogenesis. Heat shock also activated this gene while kinetin, ABA and NaCl treatment did not result in MsCPK3 mRNA accumulation. The data presented suggest that the new alfalfa CPK differs in stress responses from the previously described homologues and in its potential involvement in hormone and stress-activated reprogramming of developmental pathways during somatic embryogenesis.

A novel aldose/aldehyde reductase protects transgenic plants against lipid peroxidation under chemical and drought stresses.

Rapid accumulation of toxic products from reactions of reactive oxygen species (ROS) with lipids and proteins significantly contributes to the damage of crop plants under biotic and abiotic stresses. Here we have identified a stress-activated alfalfa gene encoding a novel plant NADPH-dependent aldose/aldehyde reductase that also exhibited characteristics of the homologous human enzyme. The recombinant alfalfa enzyme is active on 4-hydroxynon-2-enal, a known cytotoxic lipid peroxide degradation product. Ectopic synthesis of this enzyme in transgenic tobacco plants provided considerable tolerance against oxidative damage caused by paraquat and heavy metal treatment. These transformants could also resist a long period of water deficiency and exhibited improved recovery after rehydration. We found a reduced production of lipid peroxidation-derived reactive aldehydes in these transformed plants under different stresses. These studies reveal a new and efficient detoxification pathway in plants.

Immunolocalization of a novel annexin-like protein encoded by a stress and abscisic acid responsive gene in alfalfa.

We report here on the isolation and characterization of a full-length cDNA clone from alfalfa termed AnnMs2 encoding a 333 amino acid long polypeptide that shows 32-37% sequence identity with both mammalian and plant annexins, and has four tandem repeats. While other plant annexins exhibit a high level of sequence similarity to each other (up to 77% identity at amino acid level), AnnMs2 appears to be a distinct type of plant annexins. All the four endonexin folds contain the conserved eukaryotic motif within this alfalfa protein, but this element is considerably different in the second repeat. The AnnMs2 gene is expressed in various tissues of alfalfa with elevated mRNA accumulation in root and flower. This gene is activated in cells or tissues exposed to osmotic stress, abscisic acid (ABA) or water deficiency. The recombinant AnnMs2 protein is able to bind to phospholipid in the presence of Ca2+. Indirect immunofluorescence studies using affinity purified rabbit anti-AnnMs2 peptide antibody show mainly nucleolar localization, but the protein sequence lacks the usual nuclear localization signal. The potential role of this novel annexin-like protein in the basic and stress-induced cellular functions is discussed.

Household composition and agricultural technology in Zambia.

PIP: While a small percentage of Zambia's farming households practice advanced agricultural technics and produce significant yields, the majority of Zambians have barely broken out of subsistence level farming. Government programs to assist the small farmer have proven unsuccessful largely because of economic pessure to keep family members on the farm as laborers. A household's size, as well as the age and sex of its members, are crucial factors in moving the rural population toward agricultural development. A large family is clearly an asset to Zambian farmers. At peak points in the agricultural season, it is difficult to hire helpers since everyone is working on their own land, even the poor villagers. Because young men and women from poorer households tend to migrate to the cities, these families are much smaller and have fewer males than the more prosperous families. Although a Zambian man's ideal strategy is to marry several wives and raise a large number of children to ensure a labor supply, this is difficult to carry out. Only after achieving a certain minimal technological level can a farming household support a large enough group to continue to develop. The agricultural development that has taken place so far in Zambia is largely the outcome of demonstration effects and, more recently, the fruit of family remittances from the cities.^ieng