Adopting a potting method with two Sea Island cotton varieties, Xinhai 21 and Xinhai 34, and two Upland cotton varieties, Xinluzao 50 and Xinluzao 57, as materials, we examined changes in growth, chlorophyll content, net photosynthetic rate, transpiration rate, antioxidant enzyme activity, osmotic adjustment substances and malondialdehyde (MDA) content between Sea Island cotton and Upland cotton under NaCl stress. With increasing salt concentration in soil, the growth, chlorophyll content, net photosynthetic rate and transpiration rate indicators declined to different degrees in the four varieties, whereas peroxidase (POD), superoxide dismutase (SOD) and soluble sugar content showed a trend of increasing first in level and then decreasing with increasing salt concentration, proline and malondialdehyde content. Xinhai 21 and 34 showed less impact of stress than Xinluzao 57 and 50. Under 0.6% NaCl, the Sea Island cotton and Upland cotton cultivars showed good salt tolerance. The difference in salt tolerance between the two cultivated species was not significant. However, the growth of the four varieties was inhibited under 0.8% and 1.0% NaCl stress. Xinluzao 57 and 50 seedlings grew slowly, with small leaf area and little dry matter accumulation and even death. Leaves of cotton seedlings were sensitive to salt stress; the growth of leaf width and leaf length was inhibited with increasing salt concentration, which could be used as an index to select salt-tolerant varieties.

The gene MID1 (MYB IMPORTANT FOR DROUGHT RESPONSE1) encodes a putative R-R type MYB transcription factor; is induced by abiotic stresses, especially drought in reproductive stage; and can improve pollen fertility and rice production. To understand the role of MID1 in abiotic stress responses, we used the yeast two-hybrid system to find an interacting protein, OsMIP1 (Oryza sativa MID1 interaction protein 1). The interaction was further confirmed by BiFC (bimolecular fluorescence complementation) analysis in tobacco leaf cells. OsMIP1 encodes a putative transmembrane protein with an ENTH/ANTH/VHS domain. It is expressed in the root, stem, leaf, panicle and endosperm. Under drought stress, its expression is upregulated in leaf and reproductive organs, especially in post-meiotic flowers. OsMIP1 may play a role in response to drought stress during reproductive development. OsMIP1 expression during vegetative development can be induced by other abiotic stress, including NaCl and mannitol, which suggests that OsMIP1 can respond to other abiotic stresses. There is little analysis of the evolution of genes encoding proteins with the ENTH/ ANTH/VHS domain, so we analyzed the molecular evolution of MIP1 homologs in flowering plants. The evolution analysis of the MIP1 family in angiosperms showed that MIP1 homologs can be divided into 6 types, which originated from at least 6 copies of MIP1 homologous genes in the ancestor of extent angiosperms. After gene-duplication and -loss events, MIP1 family members widely distributed in the angiosperms and might have various functions, possibly in stress responses.

Dwarf rice (Oryza sativa) is the most important agronomic trait closely related to photosynthetic efficiency and yield. Exploring more dwarf resources can deepen our understanding of the genetic mechanisms of plant height and provide new germplasm for cultivating new varieties. A wide-leaf, wide-stem, small-kernel and dwarf mutant, wld1, was identified from the rice T-DNA insertion mutant library. We used map-based cloning to locate the gene on rice chromosome 5 between the markers InDel37 and InDel48, with 91 kb physical distance. The mutant wld1 resulted from deletion of the base T in LOC_Os05g32270, which causes a reading error and early termination of the peptide chain encoding. We used microscopy to observe the top-second internal structure of vegetative organs of the mutant and the wild type in paraffin sections. In the wld1, cells were significantly increased in size in cross-sections but reduced in size in longitudinal sections. The expression of LOC_Os05g32270 was completely inactivated. The gene is an allele of the reported rice gene OsSMOS1 (SMALL ORGAN SIZE1). The agronomic properties of wld1 are good (lodging) and it can be directly applied to practice. In this study, we defined the inheritance and phenotype characteristics of this mutant, which lays the foundation for further analysis of the signaling pathway.

Rice blast, caused by Magnaporthe oryzae infection, is one of the major diseases threatening the sustainable development of rice (Oryza sativa) production worldwide. Between 10% and 30% of the annual rice harvest is lost due to infection by the fungus. Development and breeding utilization of rice-resistant resources are considered the most effective and economic means to control rice blast. Isolating new virulent blast strains from the pathotype Oryza is the basis for cloning novel optimal genes resistant to rice blast and rice breeding for disease resistance. In the present study, we isolated and screened blast strains and identified new genes resistant to rice blast. Overall, 5 strains with significantly different pathogenicity between Ziyu44 and Jiangnanxiangnuo (JNXN) were identified. Eight rice varieties, including Ziyu44, Xiangzi3150, 9311, Nipponbare, Lijiangxintuanheigu (LTH), Zhonghua11, JNXN and TP309, were challenged with the 5 blast strains by spray-inoculation at seedling stage. Xiangzi3150, a variety with broad-spectrum blast resistance, showed obvious attacks after inoculation with LP11, so LP11 is probably a newly emerged strong virulent strain. The F₂ progenies derived from the cross between Ziyu44 and JNXN were inoculated with the LP11; genetic analysis and gene mapping indicated that the resistance phenotype of Ziyu44 to LP11 was controlled by a single dominant gene, and the resistance gene Pizy6(t) was located on rice chromosome 6. These results provided valuable blast strains for genetic studies of disease resistance and laid the foundation for Pizy6(t) gene cloning in Ziyu44.

MYB transcription factors play a key role in anther development and pollen formation in higher plants, and MYB80 is an important transcription factor involved in the development of tapetum and initiation of male sterility. In this study, we performed BLASTN and TBLASTX searches of the Arabidopsis thaliana MYB80 (AtMYB80) amino acid sequences against the published database and identified 2, 2 and 6 homologous sequences of MYB80 gene in Brassica rapa, B. oleracea and B. napus, respectively. The composition of nucleic acid sequence and amino acid sequences, subcellular localization, phosphorylation sites, hydrophilicity and hydrophobicity, secondary and tertiary structure of protein, conserved domains of the MYB80 were predicted and analyzed by bioinformatics tools and resources from the Internet. The results showed that the MYB80 transcription factors are located in the nucleus by analyzing subcellular localization, with a number of different phosphorylation sites, and the peptide chains are hydrophilia. The predicted secondary structure and tertiary structure showed that the main structural elements of the MYB80 protein were α helix and random coil. Conserved domain analysis indicated that the MYB80 transcription factor belongs to the MYB-R2R3 type transcription factor, with 2 tandem SANT domains in the N-terminal sequence. The multiple sequence ratio and phylogenetic tree were constructed with MYB80 proteins from different plants; similarity among B. napus and B. rapa, and B. oleracea was more than 92%, and the conserved functional domains had high homology and strong sequence conservation. These results are helpful for resolving the biological functions of MYB80 and the molecular mechanism of sterility regulation and lay a foundation for the heterosis utilization in B. napus.