Stress-induced expression of IPT gene in transgenic wheat reduces grain yield penalty under drought.

BACKGROUND: The heterologous expression of isopentenyl transferase (IPT) under the transcriptional control of the senescence-associated receptor-like kinase (SARK) promoter delayed cellular senescence and, through it, increased drought tolerance in plants. To evaluate the effect of pSARK::IPT expression in bread wheat, six independent transgenic events were obtained through the biolistic method and evaluated transgene expression, phenology, grain yield and physiological biomass components in plants grown under both drought and well-irrigating conditions. Experiments were performed at different levels: (i) pots and (ii) microplots inside a biosafety greenhouse, as well as under (iii) field conditions. RESULTS: Two transgenic events, called TR1 and TR4, outperformed the wild-type control under drought conditions. Transgenic plants showed higher yield under both greenhouse and field conditions, which was positively correlated to grain number (given by more spikes and grains per spike) than wild type. Interestingly, this yield advantage of the transgenic events was observed under both drought and well-watered conditions. CONCLUSIONS: The results obtained allow us to conclude that the SARK promoter-regulated expression of the IPT gene in bread wheat not only reduced the yield penalty produced by water stress but also led to improved productivity under well-watered conditions.

Natural occurrence of Alternaria mycotoxins in malting barley grains in the main producing region of Argentina.

BACKGROUND: Barley (Hordeum vulgare L.) is one of the most important cereals worldwide, and its quality is affected by fungal contamination such as species of the genus Alternaria. No information is available about the occurrence of Alternaria mycotoxins in Argentinean barley grains, which is of concern, because they can be transferred into malt and beer. The aim of this study was to analyze the occurrence of alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TeA) in malting barley grains from the main producing region of Argentina during the 2014 and 2015 growing seasons. RESULTS: The most frequent mycotoxin was AOH (64%), which was detected at higher levels (712 µg kg-1 ) compared with other studies, followed by TeA (37%, 1522 µg kg-1 ), while AME was present in five samples in the 2015 growing season only, with a mean of 4876 µg kg-1 . A similar frequency of mycotoxin occurrence was observed in both years (80.8 vs 85.3%), but more diverse contamination was found in 2015, which was characterized by lower accumulated precipitation. Nevertheless, AOH was more frequently found in 2014 than in 2015 (80.8 and 47.1% respectively). A negative correlation between AOH concentration and temperature was observed. The susceptibility of different barley varieties to mycotoxin accumulation varied with the mycotoxin, geographical location and meteorological conditions. CONCLUSION: The results obtained in the present work represent a tool for risk assessment of exposition to these mycotoxins and could be used by food safety authorities to determine the need for their regulation. Furthermore, the establishment of a hazard analysis and critical control point (HACCP) system to minimize fungal and mycotoxin contamination in barley from farm to processing could be apply to ensure food safety. © 2019 Society of Chemical Industry.

Natural Contamination with Mycotoxins Produced by Fusarium graminearum and Fusarium poae in Malting Barley in Argentina.

Two of the most common species of toxin-producing Fusarium contaminating small cereal grains are Fusarium graminearum and F. poae; with both elaborating diverse toxins, especially deoxynivalenol (DON) and nivalenol (NIV), respectively. The objective of our work during the 2012-2014 growing seasons was to screen crops for the most commonly isolated Fusarium species and to quantify DON and NIV toxins in natural malting-barley samples from different producing areas of Argentina. We identified 1180 Fusarium isolates in the 119 samples analyzed, with 51.2% being F. graminearum, 26.2% F. poae and 22.6% other species. We found high concentrations of mycotoxins, at maximum values of 12 µg/g of DON and 7.71 µg/g of NIV. Of the samples, 23% exhibited DON at an average of 2.36 µg/g, with 44% exceeding the maximum limits (average of 5.24 µg/g); 29% contained NIV at an average of 2.36 µg/g; 7% contained both DON and NIV; and 55% were without DON or NIV. Finally, we report the mycotoxin contamination of the grain samples produced by F. graminearum and F. poae, those being the most frequent Fusarium species present. We identified the main Fusarium species affecting natural malting-barley grains in Argentina and documented the presence of many samples with elevated concentrations of DON and NIV. To our knowledge, the investigation reported here was the first to quantify the contamination by Fusarium and its toxins in natural samples of malting barley in Argentina.