Abstract
Water deficit is an important climatic problem that can impair agriculture yield and economy. Genetically modified soybean plants containing the AtNCED3 gene were obtained aiming drought-tolerance improvement. The NCED3 gene encodes a 9-cis-epoxycarotenoid dioxygenase (NCED, EC 1.13.11.51), an important enzyme in abscisic acid biosynthesis. ABA activates the expression of drought-responsive genes, in water-deficit conditions, targeting defense mechanisms and enabling plants to survive under low water availability. Results from greenhouse experiments showed that the transgene AtNCED3 and the endogenous genes GmAREB1, GmPP2C, GmSnRK2 and GmAAO3 presented higher expression under water deficit (WD) in the event 2Ha11 than in WT-plants. No significant correlation was observed between the plant materials and WD conditions for growth parameters; however, gas exchange measurements decreased in the GM event, which also showed 80% higher intrinsic water use when compared to WT plants. In crop season 2015/16, event 2Ha11 showed higher total number of pods, higher number of pods with seeds and yield than WT plants. ABA concentration was also higher in GM plants under WD. These results obtained in field screenings suggest that AtNCED3 soybean plants might outperform under drought, reducing economic and yield losses, thus being a good candidate line to be incorporated in the soybean-breeding program to develop drought-tolerant cultivars.
Highlights
Brazil is the second country in the worldwide production and processing of soybeans, and the second largest exporter of grains and oil (Aprosoja, 2016)
The increased frequency and intensity of drought periods have generated recurrent and significant losses in soybean yield, indicating that sustainable crop production is highly dependent on the development of cultivars more tolerant to water deficit (WD), which can be obtained through available genetic engineering techniques
One hundred and eighty-four cotyledons from BRS 184 soybean conventional cultivar were transformed with the construct 35S:AtNCED3, through the Agrobacterium tumefaciens method
Summary
Brazil is the second country in the worldwide production and processing of soybeans, and the second largest exporter of grains and oil (Aprosoja, 2016). This productive chain generates 1.4 million jobs, consisting of the main contributor to the Brazilian Gross Domestic Product (GDP) (IBGE, 2016). The increased frequency and intensity of drought periods have generated recurrent and significant losses in soybean yield, indicating that sustainable crop production is highly dependent on the development of cultivars more tolerant to water deficit (WD), which can be obtained through available genetic engineering techniques. Sometimes the proof of drought tolerance improvement in real field conditions is not achieved, keeping the GM events characterization only in greenhouse
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