Lesson: Gravitropism

Tropism is a growth response between a plant and an external stimulus. The stimulus could be weather, touch, time, gravity or light. A positive response is indicated by growth toward a stimulus and a negative response is indicated by growth away from the stimulus.

Gravitropism is a plant's growth response to gravity. Typically roots grow down into the ground, and stems and leaves grow up above the ground. If one were to place a plant on its side, it would begin to bend in an upright position. This occurs because of the plant hormone also called auxin that plays a part in gravitropism. When the plant is laid on its side, the auxin concentration increases along the lower sides of the roots and stems of the plant. The auxin stimulates cell elongation on the stem which makes the stem bend up toward the sky. The auxin prohibits cell elongation in the roots which causes the roots to bend down into the soil. Gravitropism allows the plant to respond to gravity no matter what position the plant is in.

Sources:
Plants for Kids

Biology of Plants, 6th ed. Raven, Peter H., Everert, Ray F., Eichhorn, Susan E. Worth Publishing 1999.

Botany: An Introduction to Plant Biology. Mauseth, James D. Jones and Bartlett Publishers. Sudbury, Massachusetts 1998.

Blossom end rot: transport protein identified

Blossom end rot on tomatoes
(picture: Agroscope)

Poor calcium distribution in agricultural crops causes substantial loss of income every year. Now a Korean-Swiss research team under the co-leadership of plant physiologists at the University of Zurich identified a protein that regulates calcium transport in the plant root and up to the shoot. For plant breeding, the specific transport protein provides a first step toward correcting deficiency symptoms in food plants.

Blossom end rot on tomatoes and cucumbers, spotty apples – these unpleasant blemishes on fruits and vegetables not only compromises the flavor but also causes significant harvest losses every year. The characteristic blotches and spotting can be traced back to insufficient calcium uptake or faulty calcium transport within the plant. Consequently, the damage can occur even if the soil provides sufficient calcium. A team under the leadership of scientists from the University of Zurich and Pohang University of Science and Technology, Korea, has for the first time identified a protein which is responsible for the calcium transport from the root to the shoot. "Without this transport protein, plants exhibit stunted growth," explains Enrico Martinoia, Professor for Molecular Plant Physiology at the University of Zurich.

Read full press release: University of Zurich

Leafy social network: Scientists study how stomata communicate

by Mary-Ann Muffoletto

(PhysOrg.com) -- To survive, leafy plants need to take in as much carbon dioxide as possible through pores in their leaves without losing water. Known as stomata, these pores somehow work together, processing and exchanging the information necessary to open and close at opportune times to achieve constant, optimal balance.
   
An amazing and puzzling aspect of this process is that plants have no central processing unit, says Utah State University physicist David Peak.

“What we’re observing is a very primitive form of intelligence,” Peak says. “But how these stomata communicate, in what amounts to a sophisticated social network, remains a mystery.”

Peak and colleague Keith Mott, a professor of plant physiology at USU, have studied the function of stomata in intact leaves, with an emphasis on information processing, for nearly a decade. The team challenged a recent study on stomatal responses to radiant energy in a paper published in the Nov. 21, 2011 issue of Proceedings of the National Academy of Sciences.

Online Guide for Plant Physiology Textbook

An online guide is available for the 5th edition of Plant Physiology textbook by Lincoln Taiz and Eduardo Zeiger. The online guide contains Topics, Essays, Study Questions and Readings.

Links:
Online Guide: http://5e.plantphys.net/index.php
Textbook: http://www.sinauer.com/detail.php?id=8667

Current and archived copies of the monthly journal - Plant Physiology are available online:
http://www.plantphysiol.org/content/by/year

Indiana: Grow Organic clasess to begin

At least 17 instructors will present the course topics, which include history and philosophy of organic gardening, site planning and plant physiology, water and xeriscaping, soil and soil amendments, plant taxonomy, weed control, season extension, pruning, seed saving, seed starting and transplanting, annuals and perennials, insect interactions, plant pathology, genetically modified plants, tree planting and maintenance, composting / vermicomposting, vegetable gardens, and backyard habitat.

Optional Saturday field trips include a trip to an urban farm, a garden that grows medicinal and edible wild plants, the historic garden at Wylie House, and the permaculture garden in Green Acres neighborhood. There will also be a look at predators in the garden, a pruning primer and a lab at IU.

Read more at the Herald Times Online site>

High construction cost for cycads

Thomas Marler recently published the results of his research that reveal some of the attributes of the long-lived leaves of Guam's Cycas micronesica plants. "These leaves are relatively large and are constructed of tough tissues," said Marler. "Both of these factors indicate the construction costs of this leaf form are substantial."

Green leaves must pay back their own construction costs, but each leaf is also required to supply the energy needed to maintain its live tissues throughout its lifespan. Additionally, large plants like Guam's Cycas have an abundance of non-green tissue that requires energy to maintain. Therefore, large plants with this leaf construction strategy must also possess a payback strategy that allows recovery of these costs coupled with an excess in food synthesis to support plant growth. Read more> High construction cost for cycads

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Microbiology: Phytoplasma Research Begins to Bloom

By Evelyn Strauss
Bacteria belonging to an obscure group called phytoplasmas shrivel grapes in Europe and Australia; stunt corn growth in South America; destroy pears and apples in the United States and Europe; ruin peanuts, sesame, and soybean in Asia; and sicken elms, coconuts, asters, and hydrangeas on multiple continents. And as the world warms up, these attacks on food crops, lumber and shade trees, and ornamental flowers will likely grow, in part because the insects that transmit the bacteria are expected to expand their ranges north and south. For all the destruction that phytoplasmas inflict, one might expect that dozens of agricultural companies and academic labs have generated abundant amounts of information about them. But study of these plant pathogens got off to a slow start. For almost half a century, plant pathologists thought phytoplasmas were viruses. To this day, the inability to grow these bacteria outside plants or insects hinders efforts to get a handle on their biology and genomes. However, in 2004, scientists published the first full phytoplasma genomic sequence and, since then, they've completed three additional ones. With that information, researchers have begun to elucidate how phytoplasma proteins manipulate plant physiology and insect behavior, findings that might inspire novel measures to stem the devastating agricultural infections around the world.

Video: Plant Physiology: Phototropic Response (Britannica.com)

Video: Plant Physiology: Respiration (Britannica.com)

GM key to a saline solution

GENETIC modification could help alleviate a problem that affects two-thirds of Australia's wheat crop and costs grain growers $200 million a year. Australian scientists are developing salt-tolerant plants, in a bid to boost yields in areas affected by salinity. University of Adelaide professor of plant physiology Dr Mark Tester said plants were more salt-tolerant if they could keep concentrated sodium out of the shoots. Read more:

New Tools For Discovering DNA Variations In Crop Genomes

With the advent of high-throughput DNA sequencing technologies, it is now possible to cheaply and rapidly sequence hundreds of millions of bases in a matter of hours. A team of scientists have developed molecular and computational tools for the efficient and accurate identification of gene-enriched SNPs in crops.

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Profile: Jagadish Chandra Bose a plant physiologist

Sohoni Das
Go to Sohoni's Home Page
SF Hindu Examiner

Jagadish Chandra Bose was a physicist, biologist, botanist and a pioneer in the field of radio and microwave optics and made very significant contributions to plant physiology. He was able to show the similarities between the behavioral response of plant and animal tissue. He had laid the foundations of experimental science in the Indian Subcontinent. Born in Mymensingh, Bengal (Eastern India and now Bangladesh) during the colonial rule in India, graduated from St Xavier’s College, Calcutta, and joined Presidency College of University of Calcutta as a Professor of Physics. He retired and then founded the Bose Research Institute, the first scientific research institute in India.

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Phytoremediation Popularity Growing

Theresa's Biotech / Biomedical Blog
By Theresa Phillips
Tuesday June 30, 2009

Phytoremediation is a form of bioremediation that makes use of plants to degrade or sequester contaminants in soil and groundwater. While the technology is not new, it seems current trends suggest its popularity is growing. This may be due to several factors. One is that the technology has seen some significant developments and a variety of different types of phytoremediation now exist. Genetic studies and cloning technologies have helped us learn more about plant physiology and how to improve uptake or degradation rates, and the use of genetically engineered plants, better suited to the environments to which they are subjected, has improved the phytoremediation process.

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A Truce in the Crop Wars

By Mac Margolis NEWSWEEK
Published Jun 27, 2009
From the magazine issue dated Jul 13, 2009

A funny thing happened on the way to the next green revolution. The world's biggest biotech corporations have deployed the latest in genetic science to pump up yield, ward off crop disease, make food more nutritious and fundamentally reengineer what we plant and eat, and no one is complaining. Environmental groups are not shouting about the perils of "Frankenfoods." There's no rabid French cheese maker with a bad mustache leading foodies on a rampage through high-tech farms. Prince Charles is quiet. Has the war over the world's dinner table finally ended?

Not quite. Europe, much of Asia and parts of Africa fiercely resist filling the larder with genetically modified groceries, and many in agribusiness despair that they always will. So instead, they're trying to woo them with distinctly non-GM varieties. Crop scientists, seed companies and clever farmers are using the most advanced tools of science to reinvent native breeding—the age-old technique of selecting the best crops and then painstakingly breeding and crossbreeding them to make more and better food. These discoveries are remaking the world's farms by boosting productivity, creating more-nutritious food and steeling harvests against diseases and inclement weather. And yet because the new methods do not require gene splicing, they circumvent the conflict between Big Biotech and the Cassandras of food that has roiled for decades. In part, this is also a recognition that early claims for the coming genetically modified utopia were overstated.

Don't call it retro farming. Behind the revival of "traditional" farming techniques are many of the same breakthroughs in genetics, computerization and plant physiology that have driven the biotech revolution. The difference is, instead of food fashioned in the laboratory by lifting DNA from one species to another, scientists are working to unlock the secrets bundled inside each plant itself.

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BHU prof awarded Mahila Ratan

26 Jun 2009, 2136 hrs IST, TNN

VARANASI: Dr Bandana Bose, professor and former head of the department of plant physiology, Institute of Agricultural Sciences, Banaras Hindu University (BHU), has been awarded with the Best Educationist and National Mahila Ratan Gold Medal Award of Indian Solidarity Council and International Institute of Education and Management, New Delhi. According to university spokesperson, she was honoured for her remarkable contribution to education and society. She was felicitated by former governor of Tamil Nadu and Assam Dr Bhisma Narayan Singh and OP Verma, chief justice and former governor of Punjab, at a function held recently in New Delhi.

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Plant Communication: Sagebrush Engage In Self-recognition And Warn Of Danger

ScienceDaily (2009-06-20) -- Sagebrush engaged in self-recognition and communicate danger to their "clones" or genetically identical cuttings planted nearby, researchers show. ... > read full article

Venus' flytraps: Comeback of the clones

By Michael Futch

Staff writer

WHITEVILLE -- The creepy, subterranean Venus' flytrap has blossomed into a rock star at Southeastern Community College.

Near the heart of where the carnivorous plant once thrived, students are cultivating these wonders of nature in campus laboratories.
The propagation program creates tens of thousands of cloned Venus' flytraps using tissue cultures.

"It's our signature plant - the Venus' flytrap," said Becky Westbrooks, the lead faculty member of the college's natural resource area. "It will always be one of my rock stars."
The Venus' flytrap grows naturally only in an eight-county region of the coastal plain, within 70 to 90 miles of Wilmington. It is found nowhere else in the world.

The plants love high humidity and thrive in the nutrient-poor soil of this unique ecosystem.
Though not an endangered species, the plants are listed as ones of "special concern."

"It's rare, but it's not endangered. It's a step down from endangered," said Laura Gadd, a botanist with the N.C. Plant Conservation program.

Gadd cites three main reasons for the decline of Venus' flytraps in the wild: fire suppression, coastal development and poaching. Development wipes out the plant's natural habitats.

Poaching occurs on protected lands, including the Green Swamp Preserve and the Boiling Spring Lakes Preserve.

Westbrooks, who is 57, is keen on thwarting the poachers.

"If we could mass-propagate the plant and maybe flood the market, maybe we could put the poachers out of business," she said.

Students in the college's environmental science technology and biotechnology programs clone flytraps using micropropagating - a plant tissue culturing technique that uses microscopic cuttings. The process has shown to eliminate many diseases caused by viruses, bacteria and fungi.

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Vegetarian Ferns? Idaho State University researchers note simple plant species ‘consumes sugar’

ISU Headlines
Posted June 12, 2009

In a significant scientific paper soon to be published in the well respected journal Botany, Idaho State University researchers have documented how ferns, a primitive plant, “consume” sugars in early life stages.
“Ferns and their plant allies are very primitive plants that reproduce without seeds,” said Jeff Hill, ISU associate professor of biological sciences. “Sugar uptake from their environment during a microscopic phase of their life cycle is a potentially important part of their ecology. What we think is that ferns have the ability to pick up simple sugars from the soils when they germinate.”

Jeff Hill with ferns in the ISU Plant Physiology Laboratory.This challenges the basic beliefs that many have towards plants in general and opens the door for a wide range of new research on this topic.

Plants are generally thought of as self-feeders, which produce food for themselves through photosynthesis by processing light and inorganic materials. Scientists have long known that some plants, such as pitcher plants, are carnivorous and gain nitrogen and carbon nutrients by consuming insects. However, it has not been widely thought that plants uptake sugar from their environment for nourishment.

“The broad view of plants is that they are self-feeders, that by using photosynthesis they produce their own food and don’t have to go to the ‘refrigerator’ and they fix carbon from the air to eventually produce sugars,” Hill said. “We’re on the cusp of learning that, as an important part of their ecology, some plants in certain habitats have the ability to supplement and augment their photosynthetic ability by essentially grabbing free sugar from their environment.”

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Instrumentation enabling study of plant physiological response to elevated nighttime temperature

Global climate warming can affect functioning of crops and plants in the natural environment. In order to study the effects of global warming, a method for applying a controlled heating treatment to plant canopies in the open field or in the greenhouse is needed that can accept either square wave application of elevated temperature or a complex prescribed diurnal or seasonal temperature regime.

The current options are limited in their accuracy, precision, reliability, mobility or cost and scalability.

Results: The described system uses overhead infrared heaters that are relatively inexpensive and are accurate and precise in rapidly controlling the temperature. Remote computer-based data acquisition and control via the internet provides the ability to use complex temperature regimes and real-time monitoring.

Due to its easy mobility, the heating system can randomly be allotted in the open field or in the greenhouse within the experimental setup. The apparatus has been successfully applied to study the response of rice to high night temperatures.

Air temperatures were maintained within the set points + 0.5 oC. The incorporation of the combination of air-situated thermocouples, autotuned proportional integrative derivative temperature controllers and phase angled fired silicon controlled rectifier power controllers provides very fast proportional heating action (i.e.9 ms time base), which avoids prolonged or intense heating of the plant material.

Conclusion: The described infrared heating system meets the utilitarian requirements of a heating system for plant physiology studies in that the elevated temperature can be accurately, precisely, and reliably controlled with minimal perturbation of other environmental factors.

Author: Abdul MohammedLee TarpleyCredits/Source: Plant Methods 2009, 5:7