Cover illustration: Sophora (Family Leguminosae) is represented in New Zealand by a small number of species collectively known as kowhai. The bright yellow, bird-pollinated flowers are recognized by many as New Zealand's national flower. Flower development in S.tetraptera shows an unusual order and process of floral organ development. Our SEM results revealed precocious initiation and development of the carpel (C), delayed development of petals (P), and an unusual and prolonged pause in floral organ development which occurred between organ initiation and organ differentiation. Expression patterns of putative floral meristem and floral organ identity gene homologues, LEAFY (StLFY), APETALA1 (StAP1), PISTILLATA (StPI), and AGAMOUS (StAG), were quantified using qRT-PCR. Expression differences of up to 10 000-fold were detected at different stages of floral initiation and floral organ development for each gene. While two peaks in expression of StLFY and StAP1 were closely correlated to the initiation of floral organs and their subsequent differentiation, high levels of expression of StPI and StAG were detected only during floral organ differentiation (middle diagram, II and III). Expression of all four genes was particularly low during the prolonged pause in floral development. Quantitative real-time RT-PCR proved to be extremely useful in detecting a wide range of gene expression without losing precision. (See Song et al., pp. 247-259.)
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