Antisense expression of a gene encoding a calcium-binding protein in transgenic tobacco leads to altered morphology and enhanced chlorophyll

Identification of genes differentially expressed in cauliflower associated with resistance to Xanthomonas campestris pv. campestris

Black rot, caused by Xanthomonas campestris pv. campestris (Pammel) Dowson (Xcc), is one of the most damaging diseases of cauliflower and other crucifers. In order to investigate the molecular resistance mechanisms and to find the genes related to black rot resistance in cauliflower, a suppression subtractive hybridization (SSH) cDNA library was constructed using resistant line C712 and its susceptible near-isogenic line C731 as tester and driver, respectively. A total of 280 clones were obtained from the library by reverse northern blotting. Sequencing analysis and homology searching showed that these clones represent 202 unique sequences. The library included many defense/disease-resistant related genes, such as plant defensin gene PDF1.2, lipid transfer protein, thioredoxin h. Gene expression profiles of 12 genes corresponding to different functional categories were monitored by real-time RT-PCR. The results showed that the expression induction of these genes in the susceptible line C712 in response to Xcc was quicker and more intense, while in C731 the reaction was delayed and limited. Our results imply that these up-regulated genes might be involved in cauliflower responses against Xcc infection. Information obtained from this study could be used to understand the molecular mechanisms of disease response in cauliflower under Xcc stress.

[Analysis of cDNA library of Cucumis sativus L. challenged by Pseudomonas syringae pv. Lachrymans]

A cDNA library was constructed from the leaves of the disease-resistant cucumber (Cucumis sativus L.) cultivar 'D0462' challenged by Pseudomonas syringae pv. Lachrymans for 48 h. The inserted fragment sizes ranged from 0.45 to 2.1 kb and the average inserted size was 1 kb. Sequencing analysis showed that 2 352 TUTs (Tentative unique transcripts), 282 contigs, and 2 070 singlets were identified in the 2 966 ESTs derived from the cDNA library. The result of the BlastX analysis indicated that there were 1 848 ESTs with known or unknown function, 504 ESTs with no significant similarity matching with any protein or DNA sequence in the databases. In this library, many defense/disease-resistant related genes, such as metallothionein, glutathione S-transferase, ubiquitin, b-1, 3-glucanase, zinc finger protein, and cysteine protease, which might participate in the plant and the pathogens, are inclued.