Vol. 81 No: 5

Title:
A vegetative line of asparagus (Asparagus officinalis) with a homeotic change in flower development is correlated with a functional deficiency in class-B MADS-box genes

Authors:
Y. ASADA, N. KASAI, Y. ADACHI, A. KANNO, N. ITO, P.-Y. YUN and K. MASUDA

pp: 874-882

Abstract:
We describe a vegetative line of asparagus (Asparagus officinalis) that bears flowers with highly altered floral organs. Flower buds in a female line (designated ´GS#2`) of asparagus ´Gold Schatz` develop small tepals that are green in colour. Stamens are not found, but floral organs resembling carpels differentiate at positions where stamens would form. As these features appeared to indicate a homeotic mutant caused by loss of B-function in the ABC genetic model, expression analysis of class-B MADS-box genes was performed. Northern blot analysis revealed that appreciable amounts of transcripts for GLO- and DEF-like gene products were present in immature male and female flower buds of wild-type asparagus, but were lacking in those of ´GS#2`. Southern blot analysis of genomic DNA showed that there was no difference between ´GS#2` and wild-type ´Gold Schatz` when probed for DEF- and GLOlike genes.. These results demonstrate that a failure of expression of class-B genes was correlated with aberrant morphology in the floral organs of ´GS#2`. The stamens of flowers in wild-type female asparagus ceased to grow; however, the floral organs of ´GS#2` continued to develop without showing abortion.Thus, the line ´GS#2` may provide novel material for further examination of the expression of floral organ identity genes in dioecious plants that have been implicated in the sex-specific abortion of floral organs.

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