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An investigation was conducted to assess proline anabolism and catabolism pathway genes under drought stress. Treatments were irrigation in three levels (25, 50 and 100% field capacity) at 1, 3, 6 and 12 d and two rose species (Rosa canina L. and Rosa damascene Mill.). The results showed that the potential for proline accumulation in R. damascena was higher than R. canina under drought. Simultaneous with proline accumulation, expression of P5CS and P5CR genes increased from 1 to 12 d under 50% FC whereas their expression had an increasing trends from 1 to 6 d at 25% FC and expression of both genes decreased at 12 d in both species. The highest accumulation of proline was observed under 25% FC at 12 d, but expression of genes involved in proline synthesis main pathway decreased on this day. Furthermore, expression of genes (PDH and P5CDH) involved in proline catabolism pathway decreased in 50% FC from 1 to 12 d while their expression remarkably decreased from 1 to 6 d and increased at 12 d under 25% FC. These findings showed that under conditions of 50 and 25% FC, arginine accumulation resulted in the increased expression of the ARG gene, which led to ornithine production. Furthermore, ornithine accumulation increased OAT expression. Therefore, it seems that OAT-induced P5C is transported from the mitochondria to the cytosol and reduced to proline by the P5CR. • Our findings showed that under drought, arginine accumulation resulted in the increased expression of the ARG gene, which led to ornithine production. • Furthermore, ornithine accumulation increased OAT expression. • Therefore, it seems that OAT-induced P5C is transported from the mitochondria to the cytosol and reduced to proline by the P5CR. [ABSTRACT FROM AUTHOR]

In order to evaluate the genes involved in polyamines synthesis pathway and the role of nitric oxide synthase (NOS) and H 2 O 2 in stomatal closure under drought stress, a research conducted with three irrigation levels (100, 50 and 25% field capacity) at 1, 3, 6 and 12 days on Rosa damascena Mill. HPLC and qPCR results showed that putrescine (Put) accumulation occurred at first day in both 50 and 25% of field capacity and then decreased the other days. Furthermore, Put accumulation in the indirect pathway (ADC, AIH and CPA) was more effective related to the direct pathway (ODC) under severe stress. Increased expression of genes involved in production of spermidine (Spd) and spermine (Spm) i.e., SAMDC , SPDS and SPMS correlated with the highest accumulation of Spd and Spm under 50% FC at 6 d and 25% FC at 12 d, respectively. Moreover, results showed that Put reduction simultaneously accumulated H 2 O 2 , which subsequently increased NOS expression suggesting a key signal for stomatal closure. • Putrescine accumulation occurs at the first day of the treatment and then decreases on the following days converting into Spd and Spm under moderate and severe drought stress. • qPCR analysis shows that the indirect pathway of Put production was more efficient than the direct pathway.. • It seems ABA-induced stomatal closure depends on the increase of NOS gene expression, which acts as downstream signal for H 2 O 2. • Production of H 2 O 2 is itself induced by catabolism of putrescine and the processes led to increase of Ca+2 channels activity for stomatal closure. [ABSTRACT FROM AUTHOR]