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:6/30/2017)... 30, 2017 Today, American Trucking Associations ... of face and eye tracking software, became the ... program. "Artificial intelligence and advanced ... monitor a driver,s attentiveness levels while on the ... to detect fatigue and prevent potential accidents, which ...
(Date:5/23/2017)... Italy , May 23, 2017  Hunova, the first robotic gym ... trunk, has been officially launched in Genoa, Italy . ... Europe and the USA . The technology ... on the market by the IIT spin-off Movendo Technology thanks to a ... the Multimedia News Release, please click: ...
(Date:5/6/2017)... 2017 RAM Group , Singaporean ... breakthrough in biometric authentication based on a ... to perform biometric authentication. These new sensors are based ... by Ram Group and its partners. This sensor will ... chains and security. Ram Group is a next ...
Breaking Biology News(10 mins):
(Date:8/16/2017)... , ... August 16, 2017 , ... ... microbe delivery system, announced it has secured $2M in funding from an impressive ... Angels, Carmen Innovations, and SVG Thrive Fund. With this investment, 3Bar is broadening ...
(Date:8/16/2017)... WAKEFIELD, Mass. , Aug. 16, 2017  This year,s edition of ... global leader in life sciences workforce solutions, has made the list for ... Inc. 5000 recognizes the nation,s fastest-growing private companies based on a set ... Fast 50, which includes the fastest-growing companies in the Bay ... Inc. 5000 ...
(Date:8/15/2017)... , Aug. 15, 2017 After spending the past two ... with crowdsourced data collection, GeneFo now offers this platform to healthcare ... and amplifying support, adherence, and data collection vis a vis their ... mark the successful launch of this offer. ... GeneFo ...
(Date:8/15/2017)... Diego, CA (PRWEB) , ... August 15, 2017 ... ... company pioneering graphene biosensors that accelerate pharmaceutical and biotherapeutics development, announces the launch ... the number of steps needed to gain kinetic binding data for a wide ...
Breaking Biology Technology: