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M. J. Chrispeels

Publications and source records attributed to M. J. Chrispeels.

4 recordsLinked to original sources
PubMed1995

Bean [alpha]-Amylase Inhibitor Confers Resistance to the Pea Weevil (Bruchus pisorum) in Transgenic Peas (Pisum sativum L.).

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.

Journal Article↗
PubMed1993

Tonoplast and Soluble Vacuolar Proteins Are Targeted by Different Mechanisms.

The delivery of proteins to the vacuole and its limiting membrane (the tonoplast) by the secretory system is thought to be a dissociative process in which vesicles bud from one compartment and fuse with another. We studied the transport kinetics of phytohemagglutinin (PHA) and tonoplast intrinsic protein (TIP) in mesophyll protoplasts obtained from transgenic tobacco plants transformed with genes encoding these two proteins. In pulse-chase experiments, arrival of PHA in the vacuole was found to be slower (completed 24 hr after synthesis) than the arrival of TIP in the tonoplast (completed 6 hr after synthesis). Brefeldin A and monensin block protein transport by interfering in specific vesicle transport steps. Brefeldin A prevents anterograde vesicle transport between the endoplasmic reticulum and the Golgi, whereas monensin inhibits correct sorting in the trans-Golgi network by disrupting the proton gradient across the membrane. Both inhibitors blocked the transport of PHA to the vacuole and altered the rate at which its complex glycan is processed by Golgi enzymes. Neither drug stopped the arrival of TIP in the tonoplast, suggesting that the flow of vesicles continues in the presence of these inhibitors. We suggest that soluble proteins like PHA and membrane proteins like TIP reach their vacuolar destinations by different paths.

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