Salt stress reduces the fresh weight, dry weight, and relative growth rate of cucumber (Cucumis sativus) seedlings and results in serious quality loss in cucumber production. Our previous study indicated that the netting-associated peroxidase (CsaNAPOD) protein in cucumber seedling roots was induced by salt stress. Here, we amplified the coding sequence of CsaNAPOD from a cDNA isolated from the roots of cucumber seedlings. Sequence analysis indicated that the coding sequence of CsaNAPOD is 1035 bp, encoding a deduced protein of 344 amino acids, with a predicated molecular weight of 37.2 kD and theoretical isoelectric point of 5.64. The deduced amino acid sequence of CsaNAPOD showed high sequence similarity to peroxidases (PODs) from other plant species. Moreover, CsaNAPOD possesses the typical sequence structures of class III PODs and indicated that CsaNAPOD belongs to this subfamily. CsaNAPOD was highly expressed in the roots and was weakly expressed in the stems and leaves of cucumber seedlings. Salt stress significantly increased the expression of CsaNAPOD in the leaves during the entire experimental period compared with the control, and the expression of CsaNAPOD in roots was reduced at 6 hours and induced at 48 and 72 hours by salt treatment. In stems, the expression of CsaNAPOD declined at 48 and 72 hours as a result of the salt treatment compared with the control. These results indicate that the expression of CsaNAPOD responded to salt stress in cucumber seedlings, and the expression patterns under salt stress in different tissues were not identical. Our research suggests that CsaNAPOD may have potential function during the plant response to salt stress.
Huai-Fu Fan, Wen Chen, Zhou Yu and Chang-Xia Du
Xin Hao, Yu Fu, Wei Zhao, Lifei Liu, Rengui Bade, Agula Hasi and Jinfeng Hao
The MADS-box gene family encodes a type of transcription factor, and plays a key role in the growth and development of plants. Here, we identified 62 MADS-box genes in the melon (Cucumis melo) genome using bioinformatics methods. These genes were divided into type I Mα, Mγ, and Mδ subfamilies (26 members) and type II MIKCC subfamilies (36 members) by phylogenetic analysis. There were no genes in type II AGL12, BS, TM8, and MIKC* subfamilies, and type I Mβ subfamilies. Conserved motif analysis showed that all motifs had a subfamily-specific distribution except the M domain. The expression analysis of the MADS-box genes showed different expression characteristics. In summary, this study is the first to identify melon MADS-box genes and analyze their gene structures, subfamily distribution, and expression characteristics. These results provide a foundation for investigating the functions of the melon MADS-box genes.
Zhengke Zhang, Runshan Fu, Donald J. Huber, Jingping Rao, Xiaoxiao Chang, Meijiao Hu, Yu Zhang and Nina Jiang
Expansins are proteins that have been reported to contribute to fruit softening. In this study, an expansin gene, CDK-Exp3, was identified from persimmon fruit, and the mRNA accumulation of CDK-Exp3 during postharvest softening was examined using real-time polymerase chain reaction (PCR). Sequence analysis showed that CDK-Exp3 contained a putative open reading frame of 765 bp encoding a polypeptide of 254 amino acid residues, which had all the characteristics of α-expansin. As fruit softened, the expression of CDK-Exp3 increased dramatically within the initial 8-day ripening at 20 °C followed by a gradual decline at the late stages of ripening. The expression of CDK-Exp3 was inhibited by gibberellic acid, and the maximum transcript abundance was delayed by 20 days compared with that of the control fruit. The results suggest that CDK-Exp3 might be closely related to softening of persimmon fruit during postharvest ripening.
Sandy Lin, Hsiao-Ching Lee, Wen-Huei Chen, Chi-Chang Chen, Yen-Yu Kao, Yan-Ming Fu, Yao-Huang Chen and Tsai-Yun Lin
Nuclear DNA contents were estimated by flow cytometry in 18 Phalaenopsis Blume species and Doritis pulcherrima Lindl. DNA amounts differed 6.07-fold, from 2.74 pg/diploid nuclear DNA content (2C) in P. sanderiana Rchb.f. to 16.61 pg/2C in P. parishii Rchb.f. Nuclear DNA contents of P. aphrodite Rchb.f. clones, W01-38 (2n = 2x = 38), W01-41 (2n = 3x = 57), and W01-22 (2n = 4x = 76), displayed a linear relationship with their chromosome numbers, indicating the accuracy of flow cytometry. Our results also suggest that the 2C-values of the Phalaenopsis sp. correlate with their chromosome sizes. The comparative analyses of DNA contents may provide information to molecular geneticists and systematists for genome analysis in Phalaenopsis. Endoreduplication was found in various tissues of P. equestris at different levels. The highest degree of endoreduplication in P. equestris was detected in leaves.