22/10/15

It’s so sad to hear that today is our last lesson with Dr. Parameswari but luckily  we are still going to meet her due to the Scientist Trainee Programme. This week the lesson was on plant hormone. Plant hormones are chemicals that produced by plants to alter the growth pattern. We studied about five major plant hormones which are auxin, cytokinin, gibberellin, abscisic acid and ethylene.

During signal transduction in plant, hormone will bind to the receptor on the cell wall. Then molecules are relayed to the cell nucleus and response is given out. Generally, auxin induces growth in the shoot, root and stem of a plant but high concentration of auxin will inhibit the growth of root. Cytokinin promotes lateral bud growth and gibberellins breaks down seed dormancy. Abscisic acid promotes dormancy in seeds and bud while ethylene stimulates the ripening of fruit. The interaction between high ratio of auxin and low ratio of cytokinin promotes shoot growth while the opposite of it promotes root growth.

Plant is also sensitive to light and gravity. The shoot shows positive phototropism and negative gravitropism while the root is opposite to it. This is because when a plant is exposed to light, auxin moves to the sheltered part. Auxin stimulates faster cell growth and causes the shoot to bend toward light. However auxin is gathered at the lower part of the root due to gravity. This causes the suppression of root growth and the root will eventually bends downward.

In these 7 weeks, I have learnt about evolution, history of life, cell theory and prokaryote, endosymbiosis, pollination and development of plant embryo as well as plant hormones. There are some topics that I had learnt before and some I didn’t . However in overall, I gained a lot of knowledge and understood more on the topics. I believe that they would be very useful in the following studies as well as future prospect. I am glad to be Dr. Parameswari’s student because she never made the lessons boring as she carried out a lot of SCL activities which also helped us to understand more on the topics.