On the expression of several Lhc genes in garden cress (Lepidium sativum L.)

The polymerase chain reaction was used to prepare gene-specific probes for several Lhc genes coding for chlorophyll a/b-binding proteins of cress (Lepidium sativum L.). Due to the presence of about 150 basepairs of the coding region, the isolated clones could be attributed to Lhc a3 (1 clone), Lhc b1 (5 clones), Lhc b2 (1 clone) and Lhc b3 (1 clone) genes. Probes prepared from the 3'non-coding regions of the clones did not cross-hybridize; they were specific for 3 different Lhc b1 transcripts and one each of Lhc b2, Lhc b3 and Lhc a3 transcripts. The transcript levels were higher in leaves than in cotyledons of light-grown seedlings; they decreased significantly in cotyledons from week 1 to week 4. The levels of 2 Lhc b1 transcripts (detected with probes cd1 and cd2) changed from 1 week old cotyledons (30% cd1, 28% cd2) to 3 months old leaves (14% cd1), 44% cd2), stems (11% cd1, 56% cd2) and fruits (15% cd1, 62% cd2, all values percent of total transcripts), whereas transcript levels of another Lhc b1 gene (detected with probe cd3) and of a Lhc a3 gene remained nearly constant. The level of Lhc b2 and Lhc b3 transcripts were 1-2 orders of magnitude smaller than those of the other Lhc transcripts. The data obtained with cress plants are compared with published data from other plants.