l-Glutamine and l-Glutamic Acid Facilitate Successful Agrobacterium Infection of Recalcitrant Tea Cultivars

Abstract

The first step in Agrobacterium tumefaciens infection of plants is the establishment of cell-cell contact between the two partners. However, failure to establish such contact makes many plants and explants recalcitrant to A. tumefaciens infection. Tea is one such example where even the popular inducer, acetosyringone failed to facilitate A. tumefaciens infection due to the presence of high amounts of bactericidal/bacteriostatic polyphenols. Quinones are formed as a result of polyphenols oxidation. They cause tissue browning and necrosis during the process of transformation, and in turn prevent A. tumefaciens infection. Compounds such as polyphenol adsorbents, i.e., polyvinylpyrrolidone and charcoal, and antioxidants like cysteine and ascorbic acid were screened to overcome tissue browning. Although these compounds enhanced the growth of A. tumefaciens, these failed to facilitate the infection of the leaves of either Kangra Jat, Tocklai Variety-1, UPASI-9, UPASI-10, and Stock-449 cultivars of tea. On the contrary, the presence of filter sterilized L-glutamine and L-glutamic acid in the co-cultivation medium facilitated successful A. tumefaciens infection of recalcitrant tea leaves. L-Glutamine and glutamic acid form harmless adducts by binding to quinones. Therefore, their presence in the co-cultivation medium allowed the tea leaves to remain living and appealing to the infecting A. tumefaciens. Successful A. tumefaciens infection of tea leaves was confirmed by positive signals in GUS assay, PCR, and Dot blot.

Optimization of medium composition for in vitro shoot proliferation and growth of date palm cv. Mejhoul

“…l -Glutamine is an amino acid known for promoting and maintaining cell function (Newsholme et al 2003). It is involved in animal cell division (Diestel et al 2007) and is known to have anti-inflammatory properties (Jain and Khanna 1981), induce weight loss in overweight and obese human adults (Zambom de Souza et al 2015) and facilitate genetic transformation of some plant species (Kumar et al 2013). With regard to micropropagation, l -glutamine has been used to stimulate somatic embryo maturation and germination of many plant species such as Picea mariana (Khlifi and Tremblay 1995), Pinus strobus (Garin et al 2000), Larix leptolepis (Kim and Moon 2007) and Persea americana (Encina et al 2014).…”

A Perspective on Hypericum perforatum Genetic Transformation

“…Agrobacterium tumefaciens mediated transformation is the most preferred method of gene transfer due to frequent single copy transgene integration into the plant genome and low incidence of transgene silencing. The advantages of simplicity, affordable costs, lower transgenic rearrangement, ability for long DNA segment transfer, and preferential integration of foreign genes into transcriptionally active regions make A. tumefaciens -mediated transformation an attractive method (Kumar et al, 2013 ). Although this method could be useful for metabolic engineering and functional genomic studies in H. perforatum , plant recalcitrance against A. tumefaciens mediated transformation is a major concern.…”

The effect of L-glutamine on the genetic transformation of embryogenic cell suspensions of gentian species (Gentiana lutea L., Gentiana cruciata L., and Gentiana kurroo Royle) using Agrobacterium tumefaciens

“…L-glutamine works in two ways: firstly by increasing the efficiency of transformation and protecting Agrobacterium cells against the negative effect of plant-derived polyphenols and secondly by protecting the ability of bacteria to transfer fragments of T-DNA (Sandal et al, 2007). Amino acid inactivates the quinones, or the oxidized products of polyphenols, through replacement of its nitrogen atom by one of the oxygen atoms of quinones, thereby preventing their harmful effects (Kumar et al, 2013).…”