Koizumi, Ayako , Amanai, Yasuhito , Ishii, Kotaro , Nishihara, Kiyoshi , Kazama, Yusuke , Uchida, Wakana , Kawano, Shigeyuki .
Floral development of an asexual and female-like mutant carrying two deletions in gynoecium-suppressing and stamen-promoting functional regions on the Y chromosome of the dioecious plant Silene latifolia.
Sexual dimorphism in Silene latifolia is controlled by genes on the differential arm of the Y chromosome. An asexual mutant, K034 was spontaneously isolated from the inbred K-line of S. latifolia. Its stamens were suppressed completely, and its gynoecium exhibited two suppression patterns. One pattern resembled a thin rod as in wild-type males (asexual flower). The other was imperfectly suppressed, having one to three carpels (female-like flower). The ratio of those patterns was 9:1. A two-flower phenotype in which one individual or one branch has such two types of flowers is rare in S. latifolia. To examine chimerism in K034, we crossed the female-like flower of K034 with wild-type males. Some progeny obtained by this crossing have asexual and female-like flowers in one individual. This two-flower phenotype is inherited and cannot be separated. We analyzed expression of SLM1 and SLM2, orthologs of AGAMOUS and PISTILLATA, by in situ hybridization. Expression of SLM1 was limited to the floral meristem center where organs of whorls 3 and 4. At the late stage, expression of SLM2 in the stamen primordia was suppressed in asexual and female-like flowers of K034, as in wild-type females. Mitotic spreads of root tip chromosomes from hairy root cultures of K034 suggested that K034 has 25 chromosomes. Fluorescent in situ hybridization using a subtelomeric repetitive sequence, the KpnI subfamily, as a probe confirmed the existence of two submetacentric X chromosomes and one deleted and rearranged Y chromosome (Yd). PCR analysis on Yd using Y-specific STS markers (mapped by 22 previously reported hermaphroditic and asexual mutants) indicated that K034 possesses Yd carrying two deletions in gynoecium-suppressing and stamen-promoting regions.
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1 - University of Tokyo, Department of Integrated Biosciences, FSB-601, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan
2 - University of Tokyo, Department of Integrated Biosciences
3 - RIKEN, Nishina Center
4 - RIKEN, Molecular Membrane Biology Laboratory
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM