Navigation Links
Secrets in a seed: Clues into the evolution of the first flowers
Date:9/14/2009

Approximately 120-130 million years ago, one of the most significant events in the history of the Earth occurred: the first flowering plants, or angiosperms, arose. In the late 1800s, Darwin referred to their development as an "abominable mystery." To this day, scientists are still challenged by this "mystery" of how angiosperms originated, rapidly diversified, and rose to dominance. (See the January 2009 issue of the American Journal of Botany at www.amjbot.org/content/vol96/issue1.)

Studies of key features of angiosperm evolution, such as the evolution of the flower and development of the endosperm, have contributed to our current understanding of relationships among the early families of flowering plants. Examining the development of seeds and embryos among early angiosperms may help to improve our understanding of how flowering plants evolved from the nonflowering gymnosperms.

A recent study by Dr. Paula Rudall and colleagues published in the September issue of the AJB (www.amjbot.org/cgi/content/full/96/9/1581) explores a piece of this mystery: the microscopic anatomy of seed development in Trithuria, a genus in the plant family Hydatellaceae, thought to be one of the earliest families of angiospermsthe so-called "basal angiosperms."

Rudall and colleagues' observations of the development of the embryo and endosperm (tissue that surrounds the embryo and provides nutrition) in Trithuria suggest that double fertilization occurs. Double fertilization is a unique feature of flowering plants where one sperm nucleus unites with the egg, producing the embryo, while another sperm nucleus unites with a separate nucleus from the female, producing the endosperm. The endosperm is divided into two regionsthe micropylar and chalazal regions.

In Trithuria, the cells of the micropylar region divide many times to form the multi-celled endosperm. However, the chalazal region forms a single-celled haustorium, a structure that absorbs nutrients and ultimately degenerates to form an empty space in the seed. This situation is broadly similar to that of some waterlilies and some monocots but differs from that of many other early-diverging angiosperms such as Amborella, in which the endosperm is formed from the chalazal region.

One of the current hypotheses is that the endosperm originated as a monstrous proembryo that fails to develop into a plant. Rudall and colleagues' observations support this theory.

"Comparative studies of early endosperm development in extant 'basal' angiosperms (including Trithuria) tend to support this theory," Rudall said, "because there are similarities in early development of embryo and endosperm. In both cases, the first cell division produces two distinct domains that differ in their subsequent development." In the embryo, divisions of the chalazal cell produce most of the embryo. The micropylar cell develops into a stalk that attaches the embryo to the seed coat. In the endosperm of Trithuria, the chalazal haustorium may regulate early endosperm development of the micropylar region, in addition to facilitating transfer of nutrients from the perisperm, maternally derived nutritive tissue, to the embryo.

Rudall and colleagues' findings shed some light on the possible role of the endosperm in early angiosperms. "The endosperm of Trithuria, though limited in size and storage capacity, is relatively persistent," Rudall stated. "Coupled with the well-developed perisperm that occurs in Trithuria, this could indicate that the ancestral role of endosperm was to transfer nutrients from the perisperm to the embryo, rather than as a storage tissue."


'/>"/>

Contact: Richard Hund
rhund@botany.org
314-577-9557
American Journal of Botany
Source:Eurekalert

Related biology news :

1. Uncovering the secrets of ulcer-causing bacteria
2. Drug-proof zebrafish reveal secrets of addiction
3. Genetic secrets of date palm unlocked by researchers at Weill Cornell Medical College in Qatar
4. Yale researchers uncover secrets of salmonellas stealth attack
5. Diet secrets of the Royals
6. Scientists unlock the secrets of C. difficiles protective shell
7. Caltech researchers help unlock the secrets of gene regulatory networks
8. DNA testing may unlock secrets of medieval manuscripts
9. Expeditions reveal gulf of Californias deep sea secrets, as well as human imprints
10. Uncovering secrets of life in the ocean
11. Landmark study unlocks stem cell, DNA secrets to speed therapies
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/9/2016)... ISTANBUL , June 9, 2016  Perkotek an innovation leader in attendance control ... to seamlessly log work hours, for employers to make sure the right employees are ... Logo - http://photos.prnewswire.com/prnh/20160609/377486LOGO ... ... ...
(Date:6/2/2016)... 2016 The Department of Transport Management ... 44 million US Dollar project, for the , ... Personalization, Enrolment, and IT Infrastructure , to ... and implementation of Identity Management Solutions. Numerous renowned international vendors ... Decatur was selected for the most compliant and ...
(Date:5/24/2016)... 2016 Ampronix facilitates superior patient care by providing unparalleled technology to leaders ... is the latest premium product recently added to the range of products distributed by ... ... ... LCD Medical Display- Ampronix News ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... June 23, 2016 ... 2016;12(1):22-8 http://doi.org/10.17925/OHR.2016.12.01.22 Published recently ... peer-reviewed journal from touchONCOLOGY, Andrew D Zelenetz ... of cancer care is placing an increasing burden ... expensive biologic therapies. With the patents on many ...
(Date:6/23/2016)... ... June 23, 2016 , ... ... line of intelligent tools designed, tuned and optimized exclusively for Okuma CNC machining ... Chicago. The result of a collaboration among several companies with expertise in toolholding, ...
(Date:6/22/2016)... DUBLIN , June 22, 2016 Research ... and Global Markets" report to their offering. ... $39.4 billion in 2014 from $29.3 billion in 2013. The market ... (CAGR) of 13.8% from 2015 to 2020, increasing from $50.6 billion ... and projected product forecasts during the forecast period (2015 to 2020) ...
(Date:6/22/2016)... SAN DIEGO , June 22, 2016   ... the first pluripotent stem cell-derived islet replacement therapy for ... two presentations at ISSCR 2016 Annual Meeting.  ISSCR 2016, ... 22nd to 25th at Moscone West in San Francisco.  ... Details of the presentations are as follows:Event: , Focus ...
Breaking Biology Technology: