Herself's Houston Garden

Gardening for fun and wildlife at the edge of Houston's piney woods

Archive for the ‘in the news’ Category

Dodder vine (Cuscuta pentagona)

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Dodder vine is an amazing plant, it is orange rather than green due to its lack of chlorophyl, it can’t make its own food.

Instead the dodder vine hatches in the spring from a seed and very slowly moves in a circle searching the air for beta-myrcene a volatile chemical emitted into the air by tomatoes and other plants. When it picks up the scent of beta-myrcene it grows in the direction of the odor until it finds the plant emitting it.

Once it reaches the plant it tightly winds itself around the plant, sinking roots into the host plant. The roots then suck up the juices in the host plant to feed itself. The host plant will then wilt and die.

Dodder is a member of the Morning Glory family.

It has very tiny leaves that are more like scales than leaves and tiny white flowers.

It is considered an invasive plant and a threat to the local ecology in Texas.

YouTube video of dodder vine locating and reaching for a tomato plant
Cuscuta spp
Dodder management guide lines

Written by Linda MacPhee-Cobb

November 18th, 2012 at 3:51 pm

Insect damage to plants inoculates future generations

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Photo Credit

“We show that exposing tomato plants to some level of caterpillar herbivory will increase resistance for future plants—it’s sort of like a plant vaccine,” says Sergio Rasmann, a biologist at the University of Lausanne in Switzerland.

Rasmann isn’t the only one seeing this effect. In a similar study, Ann Slaughter of the Universite de Neuchatel in Switzerland infected Arabidopsis thaliana plants with a benign strain of the bacteria Pseudomonas syringae (PstavrRpt2). The offspring were more resistant to disease than control groups, which were not infected in the first generation.

How does pest resistance get inherited? Researchers point to epigenetic mechanisms, which regulate gene expression and can be passed from one generation to the next without any changes to DNA sequences. The studies suggest known epigenetic factors like DNA methylation and histone modification mediate these effects, and are among the first to demonstrate siRNAs act as an epigenetic mechanism in plant defense responses.

original story

Papers
Descendants of Primed Arabidopsis Plants Exhibit Resistance to Biotic Stress
Herbivory in the Previous Generation Primes Plants for Enhanced Insect Resistance

Written by Linda MacPhee-Cobb

February 29th, 2012 at 9:59 pm

Is Imprelis herbicide killing your trees?

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The NYTimes is reporting that several tree deaths are being linked to the use of the new herbicide Imprelis.

Imprelis uses pyrimidine carboxylic acid (trade name Aptexor )

A recently approved herbicide called
Imprelis, widely used by landscapers because it was thought to be environmentally friendly, has emerged as the leading suspect in the deaths of thousands of Norway spruce, eastern white pine and other trees on lawns and golf courses across the country.

Manufactured by DuPont and approved for sale last October by the federal Environmental Protection Agency, Imprelis is used for killing broadleaf weeds like dandelion and clover and is sold to lawn care professionals only. Reports of dying trees started surfacing around Memorial Day, prompting an inquiry by DuPont scientists.

Read more at the NYTimes Story on Imprelis

There have been several reports from both outside and within the state of Michigan of herbicide injury on Norway spruce and white pine following application of the turfgrass herbicide Imprelis (a.i. aminocyclopyrachlor). Damaged trees have symptoms consistent with growth regulator type herbicides. Injury includes curling and twisting of new growth. Pictures and comments of damage observed in Indiana can be viewed at Purdue Extension’s Plant and Pest Diagnostic Laboratory website.
Read more at the Michigan State Extension Office

WSU has photos of the damage to conifers Wilting and browning leaves at the end of branches is the most obvious symptom.

DuPont is looking into this and recommends that you do not use Imprelis near spruces or white pines for now.

Written by Linda MacPhee-Cobb

July 14th, 2011 at 5:11 pm

What pine cones reveal about the evolution of flowers

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From southern Africa’s pineapple lily to Western Australia’s swamp bottlebrush, flowering plants are everywhere. Also called angiosperms, they make up 90 percent of all land-based, plant life.

New research published this week in the Proceedings of the National Academy of Sciences provides new insights into their genetic origin, an evolutionary innovation that quickly gave rise to many diverse flowering plants more than 130 million years ago. Moreover, a flower with genetic programming similar to a water lily may have started it all.

“Water lilies and avocado flowers are essentially ‘genetic fossils’ still carrying genetic instructions that would have allowed the transformation of gymnosperm cones into flowers,” said biologist Doug Soltis, co-lead researcher at the University of Florida in Gainesville.

Gymnosperms are a group of seed-bearing plants that include conifers and cycads that produce “cones” as reproductive structures, one example being the well-known pine cone. “We show how the first flowering plants evolved from pre-existing genetic programs found in gymnosperm cones and then developed into the diversity of flowering plants we see today,” he said. “A genetic program in the gymnosperm cone was modified to make the first flower.”

But, herein is the riddle. How can flowers that contain both male and female parts develop from plants that produce cones when individual cones are either male or female? The solution, say researchers, is that a male gymnosperm cone has almost everything a flower has in terms of its genetic wiring.

Somehow a genetic change took place allowing a male cone to produce female organs as well–and, perhaps more importantly, allowed it to produce showy petal-like organs that enticed new interactions with pollination agents such as bees.

Analyzing genetic information encoded in a diverse array of evolutionarily distant flowers–water lily, avocado, California poppy and a small flowering plant frequently used by scientists as a model, Arabidopsis–researchers discovered support for the single cone theory.

A non-flowering seed plant, a cycad named Zamia, which makes pine cone-like structures instead of flowers, was also examined in the study.

“We extracted an essential genetic material, RNA, from the flowers’ specific floral organs and in the case of Zamia, its cones, to see which genes were active,” said co-lead investigator Pam Soltis, a curator at the Florida Museum of Natural History and an evolutionary geneticist at the University of Florida.

Researchers then compared the organs’ profiles to a range of species representing ancient and more recent lineages of flowering plants. “This comparison allowed us to see aspects of the floral genetic program that are shared with gymnosperms, where they came from and also which aspects are shared among different groups of flowering plants and which differ,” she explained.

The flowers of most angiosperms have four distinct organs: sepals, typically green; petals, typically colorful; stamens, male organs that produce pollen; and carpels, female organs that produce eggs. However, the flowers of more ancient lineages of angiosperms have organs that intergrade, or merge into one another through a gradual series of evolutionary reforms. For example, a stamen of a water lily produces pollen but it may also be petal-like and colorful and there is often no distinction between sepals and petals–instead, early flowers have organs called tepals.

The research team found a very significant degree of genetic overlap among intergrading floral organs in water lilies and avocado but less overlap in poppy and Arabidopsis. “In other words, the boundaries between the floral organs are not all that sharp in the early angiosperm groups-the organs are still being sorted out in a sense,” said Doug Soltis.

The finding challenged researcher expectations that each floral organ in early angiosperms would have a unique set of genetic instructions as is the case in the evolutionarily derived Arabidopsis. Instead, the finding increased the likelihood that a single male cone was responsible for the world’s first flowering plants owing to the elasticity of their genetic structure.

“In early flowers, a stamen is not much different genetically speaking than a tepal,” said Doug Soltis. “The clearly distinct floral organs we all know and love today came later in flowering plant evolution–not immediately.”

Researchers say better understanding of these genetic switches in early angiosperm flowers could one day help scientists in other disciplines such as medicine or agriculture.

This project was conducted in collaboration with scientists at Penn State University, University at Buffalo, University of Georgia, and Fudan University in Shanghai, China. It was funded in part by the National Science Foundation’s Directorate of Biological Sciences.

-NSF- source

Written by Linda MacPhee-Cobb

December 14th, 2010 at 8:48 pm