Polyamines and their biosynthesis/catabolism genes are differentially modulated in response to heat versus cold stress in tomato leaves (Solanum lycopersicum L.)

Authors: UPADHYAY, RAKESH - Purdue University; FATIMA, TAHIRA - Purdue University; HANDA, AVTAR - Purdue University; Mattoo, Autar

Submitted to: Cells
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2020
Publication Date: 7/22/2020
Citation: Upadhyay, R.K., Fatima, T., Handa, A.K., Mattoo, A.K. 2020. Polyamines and their biosynthesis/catabolism genes are differentially modulated in response to heat versus cold stress in tomato leaves (Solanum lycopersicum L.). Cells. 9:1-19.
DOI: https://doi.org/10.3390/cells9081749

Interpretive Summary: Plants are sessile and constantly face fluctuating environmental changes. Thus, their productivity and quality can be compromised. The abiotic factors such as heat, cold, drought, salt and mechanical wounding affect plant health. Among these temperature fluctuations due to high heat or cold impact, plant performance and quality can contribute to crop loss. We utilized tomato leaves to discern changes in the levels of stress-hormone polyamines and in the genes that encode anabolic and catabolic pathway enzyme genes. The changes in the polyamine pathway components at the genetic level in response to heat/cold stress were analyzed. Cellular levels of free and conjugated forms of the polyamines putrescine and spermidine were found to decline during heat stress, while they increased in response to cold stress revealing a differential response to these stresses. Discovery of such genetic modules and networks controlling the temperature stress response process in tomato are important to develop strategies to create tolerance of plants to high/low temperatures. This research is of interest to tomato breeders, scientists, plant physiologists and genetic experts.

Technical Abstract: Polyamines (PAs) regulate growth in plants and modulate the whole plant life cycle. They have been associated with different abiotic and biotic stresses, but little is known about molecular regulation involved. Here, we have explored the kinetics of PAs and their biosynthesis and catabolism genes during heat and cold stresses given independently. Genes that encode for PA anabolic and catabolic pathway enzymes in tomato (Solanum lycopersicum cv. Ailsa Craig) leaves under both stresses were quantified. These include Arginase 1 and 2, Arginine decarboxylase 1 and 2, Agmatine iminohydrolase/deiminase 1, N-carbamoyl Putrescine amidase, three Ornithine decarboxylases, three S-adenosylmethionine decarboxylases, two Spermidine synthases; Spermine synthase; flavin dependent Polyamine oxidase (SlPAO4-like and SlPAO2) and copper dependent Amine oxidases (SlCuAO and SlCuAO-like). The spatio-temporal transcript abundances using qRT-PCR revealed presence of their transcripts in all tissues examined, with higher transcript levels observed for SAMDC1, SAMDC2 and ADC2 in most tissues. Cellular levels of free and conjugated forms of putrescine and spermidine were found to decline during heat stress while they increased in response to cold stress revealing their differential responses. Transcript levels of ARG2, SPDS2, and PAO4-like increased in response to both heat and cold stresses. However, transcript levels of ARG1/2, AIH1, CPA, SPDS1 and CuAO4 increased in response to heat while those of ARG2, ADC1,2, ODC1, SAMDC1,2,3, PAO2, CuPAO4-like increased in response to cold stress, respectively. Transcripts of ADC1,2; ODC1,2; and SPMS declined in response to heat stress while ODC2 transcripts declined under cold stress. These results show differential expression of PA metabolism genes under heat and cold stresses with more impairment of PA metabolism taking place under the heat stress. We interpret these results to indicate a more pronounced role of PAs in cold stress acclimation and their inability to coordinate regulation under heat stress to be likely a reflection of lower plasticity of heat stress response.