Drought and salinity are severe environmental stresses and limit soybean growth. In this study, a comparative analysis of physiological and molecular responses of two soybean (Glycine max L.) genotypes to these stresses was carried out. Plants of drought-tolerant genotype RD (cv. FD92) and sensitive genotype SD (cv. Z1303) were exposed to 15 % (m/v) PEG 6000, which simulated drought stress, or 150 mM NaCl. The RD plants maintained larger leaf area and higher net photosynthetic rate, chlorophyll content, stomatal conductance, and relative water content compared with the SD plants. Leaf proline content increased under both stresses more in RD than in SD. The drought tolerance of RD plants was also correlated with greater antioxidant activity and lower content of hydrogen peroxide and malondialdehyde under stress conditions. Amounts of abscisic acid, jasmonic acid, and salicylic acid under stress increased to a greater extent in RD than in SD plants. At the molecular level, the effects of 20-d stress treatments were manifested by relatively higher expression of drought- or salt-related genes: GmP5CS, GmDREB1a, GmGOLS, GmBADH, and GmNCED1 in RD plants than in SD plants. These results form the basis for understanding the mechanisms of the drought- and salt-stress tolerance in soybean.

WRKY transcription factors are involved in complex signalling processes that occur during stress responses. However, in contrast to the exploration of such mechanisms in model plants, far less research has focussed on the WRKY family in cotton. We previously identified GbWRKY1 in cotton (Gossypium barbadense), the expression of which is induced upon infection by Verticillium dahliae. Our current results indicate that this gene with three introns, has a group of cis-acting elements in its promoter that are associated with plant growth and development as well as responses to environmental stresses. Here, we used virus-induced gene silencing to characterize the role of GbWRKY1. Silencing in cotton simultaneously up-regulated salicylic acid (SA)-mediated responses and inhibited jasmonate (JA)-inducible and ethylene (ET)-inducible defences, resulting in an increased susceptibility to V. dahliae. However, when compared with wild-type Arabidopsis, transgenic plants exhibited more resistance to infection with V. dahliae. In the latter genotype, expression was increased for pathogen-related PR4 and ACS2, two genes involved in the JA pathway and ET biosynthesis, while expression of PR5, involved in the SA pathway, decreased after V. dahliae infection. Moreover, POD activity and lignin content related to ethylene synthesis in transgenic Arabidopsis were higher than those in wild-type Arabidopsis after V. dahliae infection. Collectively, these findings suggest that GbWRKY1 is regulated by signalling pathways for SA, JA and ET, and mainly involved in resistance to V. dahliae attack by ET signalling pathway the response. This highlights the importance of WRKYs in regulating pathogen-induced responses and plant development.

Cotton is one of the most important economic crops in the world. Gossypium barbadense L. has higher resistance to Verticillium wilt than Gossypium hirsutum L. In the present study, seedlings of Pima90-53 (G. barbadense) had better growth performance than those of CRI8 (G. hirsutum) inoculated with Verticillium dahliae. WRKY1 genomic DNA of Pima90-53 and CRI8 were isolated (GbWRKY1 and GhWRKY1) and predicted to include three introns which were 289, 92, 87 bp and 286, 92, 87 bp in length, respectively. Compared with the DNA sequence of GbWRKY1, GhWRKY1 had a 13-base deletion in exon 4, which resulted in premature termination of translation. It was predicted that the GbWRKY1 and GhWRKY1 proteins contain two WRKY domains and zinc-finger motifs belonging to group I WRKY proteins. Two promoters, located 1745 bp and 1738 bp upstream of GbWRKY1 and GhWRKY1, were cloned and predicted to contain important regulatory elements (TATA-box, CAAT-box and pathogen/elicitor-related elements). Interestingly, compared with GbWRKY1, the GhWRKY1 promoter lacked an ethylene-responsive element (ERE) component. The relative expression of GbWRKY1, too, was higher than that of GhWRKY1 after V. dahliae and ACC (1-aminocyclopropane-1-carboxylic acid) induction. The results suggest that the difference in the promoter sequence could probably be one of the reasons that lead to different expression patterns and resistance to Verticillium wilt in Pima90-53 and CRI8.

Generation of disomic alien chromosome addition lines and alien chromosome substitution lines is important for genetic research and chromosome engineering. After determining the transmission rates for alien chromosomes, we created five Chinese kale–flowering Chinese cabbage disomic alien addition lines and one substitution line. Transmission rates ranged from 11.46 – 38.18% via the female gametes, and from 4.88 – 12.90% through the male gametes. The disomic addition lines (CC+2A₂, CC+2A₃, CC+2A₆, CC+2A₈, and CC+2A₉) were produced from selfed progenies of their corresponding monosomic addition lines. The substitution line C₁/A₉ was also obtained from the selfed progeny of monosomic line CC+A₉, following cytological identification and simple sequence repeat DNA marker analysis.

Cotton (Gossypium hirsutum) is an important economic crop, so it is of great significance to analyze its molecular mechanisms of resistance to Verticillium Wilt. The WRKY gene family encodes transcription factors (TFs) involved in plant resistance to biotic and abiotic stress. Here, we identified 17 group III WRKY genes in cotton based on the cotton genome project. The phylogenetic relationship and evolutionary of WRKY Group III TFs in Arabidopsis thaliana and G. hirsutum showed that all the WRKY Group III TFs were divided into two clades. Overall, Group III WRKYs with similar motif patterns showed a tendency to cluster into the same group in the phylogenetic tree. Elements related to jasmonic acid (JA) and salicylic acid (SA) regulation were identified in the promoter region of most WRKY Group III genes. The expression levels of five Group III genes were up-regulated more than two-fold and three genes were down-regulated after Verticillium dahliae Kleb. infection. Moreover, three group III GhWRKY genes with JA or SA regulatory element in the promoter region could be significantly induced by JA or SA, respectively. Subcellular localization and transcriptional activation analysis in yeast showed that Cot_14615 protein localized to the nucleus of mesophyll cells in Nicotiana tabacum and had transcription activation function. Our data on cotton group III WRKY genes can serve as a basis for further studies into their potential function in cotton resistant to Verticillium Wilt.