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High temperature inhibits the growth and development of maize (Zea mays L.) and wheat (Triticum aestivum L.) seedlings. The current study attempts to elucidate the underlying mechanisms of exogenous trehalose for the improvement of maize and wheat responses to heat stress. Results show that, in maize seedlings, exogenously-supplied trehalose was able to effectively elevate the capacity of photosynthetic carbon assimilation and improve the carbohydrate content via up-regulating the transcript levels of key enzymes including phosphoenol pyruvate carboxylase (PEPC), NADP-malate dehydrogenase (NADP-MDH), NADP-malic enzyme (NADP-ME), pyruvate phosphate dikinase (PPDK) and Ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit. Besides, it was also able to improve C4 pathway enzyme activities, including PEPC, NADP-MDH, NADP-ME and Ribulose-1,5-bisphosphate carboxylase (RUBPCase). In wheat seedlings, exogenously-supplied trehalose promoted photosynthetic carbon assimilation by elevating the activity of RUBPCase. These results show that exogenous trehalose improved photosynthetic carbon assimilation capacities in maize and wheat seedlings under heat stress through different mechanisms. [ABSTRACT FROM AUTHOR]

Endophytic bacteria are those that colonise the internal tissues of plant without negative impact on plant health. This work aims to isolate the endophytic bacteria colonising Triticum vulgare and Phragmites australis and evaluate their compatibility as biostimulants to maize. Three of the six obtained isolates were selected upon their surpassing ability to stimulate the growth of maize seedlings (maximum of 18% increase in germination and 2.4-fold increase in the number of lateral roots). These isolates were molecularly identified as Klebsiella MK2R2, Bacillus B2L2 and Enterobacter E1S2. The response of maize seedlings to the combined effect of these isolates revealed that Bacillus B2L2, containing treatments, surpassed the other treatments in growth vigour parameters and upon this result these treatments were applied in a field experiment either alone or in combination with 100% N fertilisation. Maize plants, inoculated with Klebsiella MK2R2 and Bacillus B2L2 either alone or in combination with Enterobacter E1S2 in the presence of urea, surpassed significantly other treatments as the weight of ear increased almost two times and the number of grains increased 1.8 times compared to the control values. It could be concluded that the obtained strains are compatible biostimulants to maize. [ABSTRACT FROM AUTHOR]