Expression of a cucumber alanine aminotransferase2 gene improves nitrogen use efficiency in transgenic rice

Abstract

BackgroundRice can absorb less than 40% of applied nitrogen fertilizer, whereas the unabsorbed nitrogen fertilizer may cause environmental problems, such as algal blooms in freshwater and increased production of nitrous oxide, a greenhouse gas which is 300 times more potent than carbon dioxide. Development of nitrogen use efficient (NUE) rice is essential for more environmentally friendly rice production. Recently, NUE rice has been developed by root-specific expression of alanine aminotransferase (AlaAT) gene from barley, a monocot plant. Therefore, we tested the efficacy of AlaAT gene from cucumber in transgenic rice, aiming to provide evidence for the conservation of AlaAT gene function in monocot and dicot.ResultsAlaAT gene from cucumber (CsAlaAT2) has been successfully cloned and constructed on pCAMBIA1300 plant expression vectors under the control of tissue-specific promoter OsAnt1. Agrobacterium tumefaciens-mediated transformation of Indonesian rice cv. Fatmawati using this construct produced 14 transgenic events. Pre-screening of T1 seedlings grown in the agar medium containing low nitrogen concentration identified selected events that were superior in the root dry weight. Southern hybridization confirmed the integration of T-DNA in the selected event genomes, each of them carried 1, 2, or 3 T-DNA insertions. Efficacy assay of three lead events in the greenhouse showed that in general transgenic events had increased biomass, tiller number, nitrogen content, and grain yield compared to WT. One event, i.e., FAM13, showed an increase in yield as much as 27.9% and higher plant biomass as much as 27.4% compared to WT under the low nitrogen condition. The lead events also showed higher absorption NUE, agronomical NUE, and grain NUE as compared to WT under the low nitrogen condition.ConclusionsThe results of this study showed that root-specific expression of cucumber alanine aminotransferase2 gene improved nitrogen use efficiency in transgenic rice, which indicate the conservation of function of this gene in monocot and dicot.

Assessment of zygosity and nitrogen used efficacy in Mekongga transgenic rice

“…Meanwhile, the M50 line revealed the highest shoot biomass and grain contents at a nitrogen fertilizer dose of 120 kg ha-1 (N3) (Figure 4). These results were in accordance with Sisharmini et al (2019) reported an increase in grain yield and tiller numbers was observed in transgenic events at 90 kg ha -1 N. 2007) and (Shrawat et al 2008) reported that overexpression of the AlaAT gene could increase not only phenotypic performances but also NUE of plants even though the alanine aminotransferase enzyme is not a key enzyme in nitrogen metabolism. NUE can be used for minimizing nutrient losses and the negative impact on the surrounding environment, as well as reducing costs associated with excessive fertilizer inputs (Galloway et al 2014).…”

Manipulating Amino Acid Metabolism to Improve Crop Nitrogen Use Efficiency for a Sustainable Agriculture

“…In addition, neither root-specific nor constitutive expression of HvALAAT1 using an ubiquitin promoter succeeded to increase plant biomass in Sorghum bicolor, and thus suggesting that ALAAT activity was not rate-limiting for NUE in Sorghum bicolor. Recent results have confirmed a link between a higher ALAAT activity in roots and improved N-related phenotypes since the expression of ALAAT2 from Cucumis sativus, ALAAT1 and ALAAT2 from Mus musculus, and ALAAT from Pyrococcus furiosus in either Arabidopsis or Oryza sativa successfully increased plant growth in high or low N conditions (McAllister and Good, 2015;Sisharmini et al, 2019). How ALAAT activity leads to improved agronomical performance of plants has not been clearly elucidated (McAllister et al, 2012).…”

New Insight into Aspartate Metabolic Pathways in Populus: Linking the Root Responsive Isoenzymes with Amino Acid Biosynthesis during Incompatible Interactions of Fusarium solani

“…Ectopic introduction of barley HvAlaAT in various N-supplied transgenic crops significantly increased the biomass and grain yield, indicating improved N use efficiency [ 76 , 77 , 78 ]. Root-specific expression of a cucumber AlaAT resulted in high N use efficiency in transgenic rice [ 79 ]. Unlike herbaceous plants, forest trees have a long lifespan and a perennial woody growth habit with sustained N nutrition by seasonal and internal cycling; therefore, investigating N’s molecular factor and regulatory mechanisms has excellent environmental significance in Populus .…”