Numerous Trichoderma strains have been reported to be optimal biofertilizers and biocontrol agents with low production costs and environmentally friendly properties. Trichoderma spp. promote the growth and immunity of plants by multiple means. Interfering with the hormonal homeostasis in plants is the most critical strategy. However, the mechanisms underlying plants’ responses to Trichoderma remain to be further elucidated. Auxin is the most important phytohormone that regulates almost every aspect of a plant’s life, especially the trade-off between growth and defense. The AUXIN RESPONSE FACTOR (ARF) family proteins are key players in auxin signaling. We studied the responses and functions of the PdPapARF1 gene in a hybrid poplar during its interaction with beneficial T. asperellum strains using transformed poplar plants with PdPapARF1 overexpression (on transcription level in this study). We report that PdPapARF1 is a positive regulator for promoting poplar growth and defense responses, as does T. asperellum inoculation. PdPapARF1 also turned out to be a positive stimulator of adventitious root formation. Particularly, the overexpression of PdPapARF1 induced a 32.3% increase in the height of 40-day-old poplar plants and a 258% increase in the amount of adventitious root of 3-week-old subcultured plant clones. Overexpressed PdPapARF1 exerted its beneficial functions through modulating the hormone levels of indole acetic acid (IAA), jasmonic acid (JA), and salicylic acid (SA) in plants and activating their signaling pathways, creating similar results as inoculated with T. asperellum. Particularly, in the overexpressing poplar plants, the IAA level increased by approximately twice of the wild-type plants; and the signaling pathways of IAA, JA, and SA were drastically activated than the wild-type plants under pathogen attacks. Our report presents the potential of ARFs as the crucial and positive responders in plants to Trichoderma inducing.
Abstract. Water level is an indicating factor in flood control in the plain river network region of Taihu Basin (PRNRTB). It is mainly influenced by climate change and human activity. In this study, the annual and seasonal variations of extreme water level from 1960 to 2012 were analyzed based on daily water level of eight stations in the PRNRTB. The modified Mann-Kendall test and sequential cluster analysis are used to detect trends and points of abrupt change. The results indicated that the extreme water level shows a significant increase at a regional scale. The 10 increases in extreme high water level (EHWL) and extreme low water level (ELWL) were 0.007 and 0.01 m per year, respectively. Detected points of abrupt change was around 1988 for the region and most stations, which correspond to the period of intensive human activities in this region. The changes in average annual EHWL and ELWL between 1989 and 2012 are, respectively, 7.8% and 12.7% higher than that between 1960 and 1988. Meanwhile, contributions of precipitation and human activity were also assessed in three individual periods (1989-2012, 1989-2000, and 15 2000-2012). Between 1989 and 2012, the contribution from human activity increased from 20.5% to 70.3% for EHWL, while human activity was always the main driver responsible for the increase in ELWL in that period. In addition, a thorough discussion is included about the potential driving force on the extreme water level in the PRNRTB. Human activities are suggested to have played more and more important roles in the extreme water level changes since the late 1980s. The results of the study would provide support in water resources management and floods control in urban 20 development.
Bioactive gibberellins (GAs) affect nearly every process during plant growth and development. In the present study, endogenous GA 3 and GA 4 levels in young leaves of 2-to 4-year-old birch (Betula platyphylla) trees were analyzed using liquid chromatography-tandem mass spectrometry (
Some indole-3-acetic acid amido synthetases (GH3 proteins) were confirmed to catalyze the connection between IAA, SA or JA with amino acid to regulate hormone dynamic balances in promoting plant growth; they can also improve plants' resistance to stress through activating SA, JA and ethylene signaling pathways. Trichoderma spp. are widely-known beneficial biocontrol agents. However, the expression pattern of plant GH3 genes induced by Trichoderma remained unexplored. In this study, five GH3 genes in Populus davidiana × P. alba var. pyramidalis (named PodaGH3-1, PodaGH3-2, PodaGH3-5, PodaGH3-9 and PodaGH3-10) were cloned. Their characteristic analysis showed that the five PodaGH3s genes were highly conservative and closely related at the residues linked to ATP binding with IAA or JA, and their expression levels changed obviously under Trichoderma inoculation. Moreover, IAA, JA and SA contents showed a fluctuating yet increasing trend during the 72 hours when poplar seedling rhizosphere was colonized by Trichoderma. In summary, all the five PodaGH3s could be activated by the interaction between biotrophic Trichoderma and poplar seedlings.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.