分类： 生物学 >> 植物学 >> 植物生理学 提交时间： 2016-05-04
Elise K. Pasoreck
Jin Su
Ian M. Silverman
Sager J. Gosai
Brian D. Gregory
Joshua S. Yuan
Henry Daniell
摘要： The impact of metabolic engineering on nontarget pathways and outcomes of metabolic engineering from different genomes are poorly understood questions. Therefore, squalene biosynthesis genes FARNESYL DIPHOSPHATE SYNTHASE (FPS) and SQUALENE SYNTHASE (SQS) were engineered via the Nicotiana tabacum chloroplast (C), nuclear (N) or both (CN) genomes to promote squalene biosynthesis. SQS levels were ~4300-fold higher in C and CN lines than in N, but all accumulated ~150-fold higher squalene due to substrate or storage limitations. Abnormal leaf and flower phenotypes, including lower pollen production and reduced fertility, were observed regardless of the compartment or level of transgene expression. Substantial changes in metabolomes of all lines were observed: levels of 65120 unrelated metabolites, including the toxic alkaloid nicotine, changed by as much as 32-fold. Profound effects of transgenesis on nontarget gene expression included changes in the abundance of 19076 transcripts by up to 2000-fold in CN; 7784 transcripts by up to 1400-fold in N; and 5224 transcripts by as much as 2200-fold in C. Transporter-related transcripts were induced, and cell cycle-associated transcripts were disproportionally repressed in all three lines. Transcriptome changes were validated by qRT-PCR. The mechanism underlying these large changes likely involves metabolite-mediated anterograde and/or retrograde signalling irrespective of the level of transgene expression or end product, due to imbalance of metabolic pools, offering new insight into both anticipated and unanticipated consequences of metabolic engineering.
分类： 生物学 >> 植物学 >> 植物生理学 提交时间： 2016-05-03
摘要： The whitefly (Bemisia tabaci) causes tremendous damage to cotton production worldwide. However, very limited information is available about how plants perceive and defend themselves from this destructive pest. In this study, the tran WRKY40 and copper transport protein are hub genes that may regulate cotton defenses to whitefly infestation. Silencing GhMPK3 by virus-induced gene silencing (VIGS) resulted in suppression of the MPK-WRKY-JA and ET pathways and lead to enhanced whitefly susceptibility, suggesting that the candidate insect resistant genes identified in this RNA-Seq analysis are credible and offer significant utility. Taken together, this study provides comprehensive insights into the cotton defense system to whitefly infestation and has identified several candidate genes for control of phloem-feeding pests.
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