RESUMO
Bruchid larvae cause major losses of grain legume crops through-out the world. Some bruchid species, such as the cowpea weevil and the azuki bean weevil, are pests that damage stored seeds. Others, such as the pea weevil (Bruchus pisorum), attack the crop growing in the field. We transferred the cDNA encoding the [alpha]-amylase inhibitor ([alpha]-AI) found in the seeds of the common bean (Phaseolus vulgaris) into pea (Pisum sativum) using Agrobacterium-mediated transformation. Expression was driven by the promoter of phytohemagglutinin, another bean seed protein. The [alpha]-amylase inhibitor gene was stably expressed in the transgenic pea seeds at least to the T5 seed generation, and [alpha]-AI accumulated in the seeds up to 3% of soluble protein. This level is somewhat higher than that normally found in beans, which contain 1 to 2% [alpha]-AI. In the T5 seed generation the development of pea weevil larvae was blocked at an early stage. Seed damage was minimal and seed yield was not significantly reduced in the transgenic plants. These results confirm the feasibility of protecting other grain legumes such as lentils, mungbean, groundnuts, and chickpeas against a variety of bruchids using the same approach. Although [alpha]-AI also inhibits human [alpha]-amylase, cooked peas should not have a negative impact on human energy metabolism.
RESUMO
We have developed a rapid and reproducible transformation system for subterranean clover (Trifolium subterraneum L.) using Agrobacterium tumefaciens-mediated gene delivery. Hypocotyl segments from seeds that had been allowed to imbibe were used as explants, and regeneration was achieved via organogenesis. Glucose and acetosyringone were required in the co-cultivation medium for efficient gene transfer. DNA constructs containing four genes encoding the enzymes phosphinothricin acetyl transferase, [beta]-glucuronidase (GUS), neomycin phosphotransferase, and an [alpha]-amylase inhibitor were used to transform subterranean clover. Transgenic shoots were selected on a medium containing 50 mg/L of phosphinothricin. Four commercial cultivars of subterranean clover (representing all three subspecies) have been successfully transformed. Southern analysis revealed the integration of T-DNA into the subterranean clover genome. The expression of the introduced genes has been confirmed by enzyme assays and northern blot analyses. Transformed plants grown in the glasshouse showed resistance to the herbicide Basta at applications equal to or higher than rates recommended for killing subterranean clover in field conditions. In plants grown from the selfed seeds of the primary transformants, the newly acquired gene encoding GUS segregated as a dominant Mendelian trait.
RESUMO
A reproducible transformation system was developed for pea (Pisum sativum L.) using as explants sections from the embryonic axis of immature seeds. A construct containing two chimeric genes, nopaline synthase-phosphinothricin acetyl transferase (bar) and cauliflower mosaic virus 35S-neomycin phosphotransferase (nptII), was introduced into two pea cultivars using Agrobacterium tumefaciens-mediated transformation procedures. Regeneration was via organogenesis, and transformed plants were selected on medium containing 15 mg/L of phosphinothricin. Transgenic peas were raised in the glasshouse to produce flowers and viable seeds. The bar and nptII genes were expressed in both the primary transgenic pea plants and in the next generation progeny, in which they showed a typical 3:1 Mendelian inheritance pattern. Transformation of regenerated plants was confirmed by assays for neomycin phosphotransferase and phosphinothricin acetyl transferase activity and by northern blot analyses. Transformed plants were resistant to the herbicide Basta when sprayed at rates used in field practice.
