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Article|19 Nov 2022|OPEN
Reduced γ-glutamyl hydrolase activity likely contributes to high folate levels in Periyakulam-1 tomato
Kamal Tyagi1,2 , Anusha Sunkum1 , Prateek Gupta1 , Himabindu Vasuki Kilambi1 and Yellamaraju Sreelakshmi1 , , Rameshwar Sharma,1 ,
1Repository of Tomato Genomics Resources, Department of Plant Sciences, University of Hyderabad, Hyderabad-500046, India
2Current Address: Horticulture Section, SIPS, Cornell University, Ithaca, NY-14853, USA
*Corresponding author. E-mail:,

Horticulture Research 10,
Article number: uhac235 (2023)
Views: 330

Received: 19 Aug 2022
Accepted: 12 Oct 2022
Published online: 19 Nov 2022


Tomato cultivars show wide variation in nutraceutical folate in ripe fruits, yet the loci regulating folate levels in fruits remain unexplored. To decipher regulatory points, we compared two contrasting tomato cultivars: Periyakulam-1 (PKM-1) with high folate and Arka Vikas (AV) with low folate. The progression of ripening in PKM-1 was nearly similar to AV but had substantially lower ethylene emission. In parallel, the levels of phytohormones salicylic acid, ABA, and jasmonic acid were substantially lower than AV. The fruits of PKM-1 were metabolically distinct from AV, with upregulation of several amino acids. Consistent with higher °Brix, the red ripe fruits also showed upregulation of sugars and sugar-derived metabolites. In parallel with higher folate, PKM-1 fruits also had higher carotenoid levels, especially lycopene and β-carotene. The proteome analysis showed upregulation of carotenoid sequestration and folate metabolism-related proteins in PKM-1. The deglutamylation pathway mediated by γ-glutamyl hydrolase (GGH) was substantially reduced in PKM-1 at the red-ripe stage. The red-ripe fruits had reduced transcript levels of GGHs and lower GGH activity than AV. Conversely, the percent polyglutamylation of folate was much higher in PKM-1. Our analysis indicates the regulation of GGH activity as a potential target to elevate folate levels in tomato fruits.