Abstract

Restoring an Evolutionary Lost Trait through the Understanding of Silicon uptake Mechanism in Tomato

Rupesh Deshmukh, Ramalingaswami Fellow (Scientist D), National Agri-Food Biotechnology Institute

Silicon (Si) has been universally recognized as a beneficial element due to its prophylactic effects on plant growth. However, tomato, a member of Solanaceae, lacks the ability to uptake substantial quantities of Si. To understand this constraint, comparative genomics was performed on 25 diverse plant species. The results revealed that all species carrying Nodulin-26 like intrinsic protein-III (NIP-III), a class of aquaporins, were capable to uptake Si, with the exception of tomato and citrus. Further comprehensive analysis of NIP-IIIs inferred the selective role of a 108-amino acid (AA) spacing between the two conserved NPA motifs for Si permeability. Functional analysis of NIP-IIIs performed using the Xenopus oocyte assay and heterologous expression in Arabidopsis confirmed Si-transport activity in NIP IIIs with 108 AA whereas those of tomato (109-AA) and citrus (43-AA) were found to be non-functional. On the other hand, tomato plants transformed with a well-characterized Si-transporter. TaLsi1, from wheat showed improved Si uptake and enhanced resilience under biotic and abiotic stress. Efforts are being made toward restoration of a Si-permeable NPA spacing in tomato NIP-III using genome editing approach.