Expression of Agrobacterium Isopentenyl transferase (IPT) gene in wheat improves drought tolerance.

Abstract

Drought, as an abiotic stressor, globally limits cereal productivity, leading to early aging of leaves and lower yields. The expression of the isopentenyl transferase (IPT) gene, which is involved in cytokinin (CK) biosynthesis, can delay drought-induced leaf senescence. In this study, the Agrobacterium Isopentenyl transferase (IPT) gene was introduced into two local hexaploid wheat cultivars, NR-421 and FSD-2008. The expression cassette was developed containing the IPT gene under transcriptional regulation of the stress-inducible promoter 'Dehydrin,' sourced from Hordeum vulgare. The gene expression cassette was assembled in pSB219M, a modified transformation vector for monocots, equipped with both an antibiotic (spectinomycin) and an herbicide selection marker (BASTA). Initial screening of transgenic plants involved BASTA selection (2 and 3 mg/L) and was subsequently confirmed through PCR analysis. The transformation efficiencies of NR-421 and FSD-2008 were 0.4% and 0.3%, respectively. The qRT-PCR analysis under stress conditions showed a 13.5-fold higher expression of the IPT gene in T₂ transgenic plants of NR-421 and a 5.8-fold higher expression in those of FSD-2008 than in non-transgenic controls. Under stress conditions, the wheat transgenic plants exhibited increased chlorophyll and relative water content. Additionally, for total soluble proteins, two transgenic lines from the NR-421 variety showed a significant increase, whereas no notable change was observed in the FSD-2008 transgenics. Moreover, the transgenic lines displayed increased plant height, higher fresh and dry biomass, and increased seed weight compared to the non-transgenic controls. These findings highlight that stress-inducible expression of the IPT gene in wheat leads to enhanced grain yield and subsequently improved drought tolerance.