Mor Genetics MOR

Cell division in plants is a process that is currently under intense study by biologists. One team of researchers in Australia has recently published a paper describing their research into the role that microtubules play in cell division and morphogenesis. While these structures have been identified to be involved in cell division and growth, how they form, disassemble, and reappear is not fully understood. The Australian team's research consisted of their testing the hypothesis that a gene in the plant A. thaliana, called mor 1, plays a role in the development of microtubules.

In order to test this hypothesis, the team determined that the mor1 locus in a mutant A. thaliana caused temperature sensitive mutations in the development of microtubules when the temperature was increased from 21?C to 29?C. They used immunofluorescence microscopy, a technique that stains cell structures with a fluorescent dye, to visualize the actual microtubules of both wild type and mutant A. thaliana...

The mutant A thaliana, were determined to contain two mutant alleles, each having "single amino-acid substitutions in the HEAT repeat nearest the N. terminus." (Whittington 611) When exposed to temperatures of 29 ?C for a period of 90 minutes, the mutant samples displayed non-transverse orientation and "patchy diffuse fluorescence developed…eventually the microtubules became relatively short, sparse, and misaligned…" (Whittington 611) Normal microtubule organization returned to the mutant samples quickly after lowering the temperature back to 20?C.
The researchers also grew wild and mutant seedlings of A. thaliana and observed that when raised in an environment of 29?C, the mutant plants were "extremely squat, do not develop flowers and eventually die." (Whittington 612) This result reinforced the hypothesis that two alleles within the mor1 gene contain mutations which confer temperature sensitivity to the formation of microtubules within the plant's cells. In other words,…