Gain of expression in the sporophyte in the absence of a functional embryo sac: expression analysis in the coatlique (coa) mutant. (a) RT-PCR for 11 genes in coa and wild-type (WT) pistils. Equal loading of both coa and WT cDNA templates in PCR was monitored by expression of ACT11. SUP, SUPERMAN. Also shown are in situ expression patterns of the following genes in coa pistil tissues: (b) AT4G12410, encoding an auxin-responsive Small Auxin Up RNA (SAUR) protein; (c) AT1G75580, encoding an auxin-responsive protein; (d) AT5G03200, encoding a C3HC4-type RING finger protein; and (e) at5g15980, encoding a PPR repeat containing protein. The corresponding sense control probes did not show any expression (data not shown). (f) AT4G12410 did not show any detectable expression pattern in wild-type pistils. The other four genes exhibited spatial expression patterns in the wild-type ovule and carpel tissues comparable to that of coa, but their wild-type expression levels were much lower than in coa (data not shown). (g) We initially identified the over-expression of STM in the ovule tissues of spl (sensu microarray data), and confirmed that this gene is over-expressed in the carpel and ovules of coa as well (panels a and g). (h) A comparable but less intense spatial expression pattern of STM was seen in wild-type pistils. Scale bars: 100 μm in panels b to h.