In this study, we identified and characterized seven cDNA fragments differentially expressed in the pollinated and non-pollinated ovaries of Cymbidium hybridium using mRNA differential display RT-PCR(DDRT-PCR). Deduced aminoacid sequences of four of the seven cDNA fragments (CDD-313, CDD-272,CDD-265, CDD-243) showed no significant homology with ESTs and genes in the Genbank databases. However, the remaining three (CDD-193, CDD-218, CDD-470) showed significant homologies with sequences encoding components of an ABC-type transporter, GTPase and 40S ribosomal S3 proteins (RPS3) , respectively. Their differential expression patterns were confirmed by reverse Northern blot analysis. CDD-470, which encoded a new factor of RPS3 participating in cell growth and proliferation, appeared to be present and highly expressed in the pollinated ovaries. Based on these results, we deduced that this 40S ribosomal S3 like protein was most likely involved in the ovary development of orchids, and the study gave us novel insights into the molecular mechanism of the ovary and floral development of orchids.
The effect of green spot disease (Apatococcus lobatus) parasitization on diurnal variation of photosynthesis of valencia orange trees ( Citrus ‘Olinda’) was studied by portable photosynthesis system LI-6400 with 2-year pot-grown grafting seedlings. The results showed that diurnal course in net photosynthetic rate (Pn) and stomatal conductance (Gs) of leaveswith low severity (5% ) presented two peaks, transp iration rate ( Tr) appeared single peak, intercellular CO2 concentration (Ci) before noon greatly declined and
lower Ci was kep t afternoon. Leaves with slight severity were similar to healthy leaves in diurnal variation of photosynthesis, their photosynthesis appeared ‘Wuxiu’phenomenon, and mainly controlled by stomatal factors. Diurnal changes in photosynthesis of leaveswith medium severity (40%) and high severity (80% ) were different greatly from the healthy leaves, their diurnal curve of Pn, Gs, and Tr declined sharp ly, Ci decreased slowly before noon and higher Ciwasmaintained in the whole afternoon, their photosynthesis was mainly controlled by non-stomatal factors.