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The gigas mutant in pea is deficient in the floral stimulus


Beveridge, CA and Murfet, IC, The gigas mutant in pea is deficient in the floral stimulus, Physiologia Plantarum, 96, (4) pp. 637-645. ISSN 0031-9317 (1996) [Refereed Article]

DOI: doi:10.1111/j.1399-3054.1996.tb00237.x


Identification of a gene acting in the floral stimulus pathway should provide a basis for determining the identity of this elusive substance. Our tests indicate the Gi (gigas) gene in pea (Pisum sativum L.) acts in this manner. The gigas mutant was selected by Dr M. Vassileva following gamma radiation of the late flowering, quantitative long day cultivar Virtus. The gigas trait showed single gene recessive inheritance and the mutant allele was symbolised gi consistent with our preliminary report. Gigas plants were later flowering than the initial line in all conditions tested and they showed an enhanced response to photoperiod and vernalisation. Unvernalised gigas plants did not flower under a 24-h photoperiod comprising 8 h of daylight and 16 h of weak (3 umol m-2 s-1) incandescent light and they took on a phenotype similar to the vegl (vegetative) mutant in pea. However, genetic tests showed the two mutants were not allelic. Three or four weeks vernalisation at 4°C resulted in 100% flowering of gigas plants under the 24-h photoperiod. Applied gibberellin A3 inhibited flowering in gigas plants given partial cold induction. Grafting studies showed the promotive effect of vernalisation occurred in the shoot. Grafting studies were also used to examine the physiological basis of delayed flowering in the gigas mutant. These studies indicated that gigas plants produced normal levels of flower inhibitor and they responded in a normal manner to the floral stimulus. Reciprocal grafts were made between the gigas mutant and the wild-type initial line. Under the 24-h photoperiod, either a wild-type root-stock with cotyledons or a wild-type shoot induced flowering in a gigas graft partner. However, under a 9-h photoperiod, flowering was only induced if the wild-type partner possessed both roots and a shoot. We conclude that gigas plants are deficient in the floral stimulus or a precursor which can be supplied across a graft union by a wild-type donor. Of the 12 major flowering genes known in pea, Gi is the first found to act on the synthesis pathway for the floral stimulus.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:Murfet, IC (Professor Ian Murfet)
ID Code:7026
Year Published:1996
Web of Science® Times Cited:48
Deposited By:Plant Science
Deposited On:1996-08-01
Last Modified:2011-08-16

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