Response of root morphology, physiology and endogenous hormones in maize(Zea mays L.) to potassium deficiency

Potassium （K） deficiency is one of the major abiotic stresses which has drastically influenced maize growth and yield around the world. However, the physiological mechanism of K deficiency tolerance is not yet fully understood. To identify the differences of root morphology, physiology and endogenous hormones at different growing stages, two maize inbred lines 90-21-3 （tolerance to K deficiency） and D937 （sensitive to K deficiency） were cultivated in the long-term K fertilizer experimental pool under high potassium （＋K） and low potassium （-K） treatments. The results indicated that the root length, volume and surface area of 90-21-3 were significantly higher than those of D937 under -K treatment at different growing stages. It was noteworthy that the lateral roots of 90-21-3 were dramatically higher than those of D937 at tasselling and flowering stage under-K treatment. Meanwhile, the values of superoxide dismutase （SOD） and oxidizing force of 90-21-3 were apparently higher than those of D937, whereas malondialdehyde （MDA） content of D937 was obviously increased. Compared with ＋K treatment, the indole-3-acetic acid （IAA） content of 90-21-3 was largely increased under-K treatment, whereas it was sharply decreased in D937. On the contrary, abscisic acid （ABA） content of 90-21-3 was slightly increased, but that of D937 was significantly increased. The zeatin riboside （ZR） content of 90-21-3 was significantly decreased, while that of D937 was relatively increased. These results indicated that the endogenous hormones were stimulated in 90-21-3 to adjust lateral root development and to maintain the physiology function thereby alleviating K deficiency.

Development of lepidopteran pest-resistant transgenic japonica rice harboring a synthetic cry2A* gene

A synthetic cry2A^＊ gene enco ding Bacillus thuringiensis（Bt） δ-endotoxi n that resi st ance to lepidopteran pest was transformed into japonica rice variety Jijing 88, which is the most widely cultivated variety in Jilin Province, Northeast China, by Agrobacterium-mediated transformation. A total of 106 independent transformants overexpressing cry2A^＊ gene driven by ubiquitin（Ubi） promoter was produced. Three single-copy homozygous transgenic lines were finally selected based on the results of PCR analysis, se gregation ratio of Bast a resistance, and Southern hybridiza tion analyse s. RT-PCR and enzyme linke dimmune sorbent assay（ELISA） revealed that cry2A^＊ transcripts and protein were highly expressed in these lines. The high level of Cry2A^＊ protein expression resulted in high resistance to rice striped stem borer as evidence d by insect feeding bioassays. Our results demonst rate that cry2A^＊ transgenic japonica rice confers resistance to the rice striped stem borer in the laboratory conditions.

RNA-seq analysis for soybean cyst nematode resistance of Glycine soja(wild soybean)

To explore genetic resource of wild soybean(Glycine soia. L), RNA-seq was used to investigate cyst nematode resistance of G. soja. Root transcriptome expressions were profiled at 9, 15 and 20 d post inoculation(DPI) in resistant and susceptible G. soja to SCN(soybean cyst nematode). A total of 1,594 differentially expressed genes(DEGs) were identified in roots infected by SCN compared with non-infected roots. In the resistant accession, 619, 65, and 8 DEGs were detected at 9, 15, and 20 DPI, respectively, while 327, 460 and 115 DEGs were detected at the same sampling point of susceptible accessions. DEGs were enriched in peroxidase gene sets which were involved in response to oxidative stress and oxidation reduction. Two gene families, ZIM transcription factor and WRKY transcription factor were enriched. WRKY transcription factor was only enriched in resistant accession. Moreover, gene expressions of 9 DEGs were validated by qRT-PCR. XLOC_023202, an unknown protein was up regulated more than 5 fold at 9 and 15 DPI in the resistant accession. These results provided an atlas of gene expressions of G. soja in response to SCN infection, and identified candidate DEGs for future research.