Bt Jute Expressing Fused δ-Endotoxin Cry1Ab/Ac for Resistance to Lepidopteran Pests

Abstract

Jute (Corchorus sp.) is naturally occurring, biodegradable, lignocellulosic-long, silky, golden shiny fiber producing plant that has great demands globally. Paper and textile industries are interested in jute because of the easy availability, non-toxicity and high yield of cellulosic biomass produced per acre in cultivation. Jute is the major and most industrially used bast fiber-producing crop in the world and it needs protection from insect pest infestation that decreases its yield and quality. Single locus integration of the synthetically fused cry1Ab/Ac gene of Bacillus thuringiensis (Bt) in Corchorus capsularis (JRC 321) by Agrobacterium tumefaciens-mediated shoot tip transformation provided 5 potent Bt jute lines BT1, BT2, BT4, BT7 and BT8. These lines consistently expressed the Cry1Ab/Ac endotoxin ranging from 0.16 to 0.35 ng/mg of leaf, in the following generations (analyzed upto T4). The effect of Cry1Ab/Ac endotoxin was studied against 3 major Lepidopteran pests of jute- semilooper (Anomis sabulifera Guenee), hairy caterpillar (Spilarctia obliqua Walker) and indigo caterpillar (Spodoptera exigua Hubner) by detached leaf and whole plant insect bioassay on greenhouse-grown transgenic plants. Results confirm that larvae feeding on transgenic plants had lower food consumption, body size, body weight and dry weight of excreta compared to non-transgenic controls. Insect mortality range among transgenic feeders was 66–100% for semilooper and hairy caterpillar and 87.50% for indigo caterpillar. Apart from insect resistance, the transgenic plants were at par with control plants in terms of agronomic parameters and fiber quality. Hence, these Bt jutes in the field would survive Lepidopteran pest infestation, minimize harmful pesticide usage and yield good quality fiber.

Assessment of Pigeonpea (Cajanus cajan L.) transgenics expressing Bt ICPs, Cry2Aa and Cry1AcF under nethouse containment implicated an effective control against herbivory by Helicoverpa armigera (Hübner)

“…Since the 1990s, this strategic biotechnological approach has been increasingly adopted in many parts of the world, especially for corn and cotton pest management. The utility of Bt ICPs in conferring resistance to varied pests has been demonstrated in a wide range of crops . In pigeonpea, major crop losses resulting in stagnated productivity are mainly due to various biotic and abiotic factors, including herbivory by H. armigera .…”

“…The utility of Bt ICPs in conferring resistance to varied pests has been demonstrated in a wide range of crops. [39][40][41][42][43] In pigeonpea, major crop losses resulting in stagnated productivity are mainly due to various biotic and abiotic factors, 1,2,44 including herbivory by H. armigera. 45,46 A major impetus for the mitigation of this pest in pigeonpea has been transgenesis due to the lack of availability of resistance sources in the cultivated germplasm.…”

The Development of Macrophomina phaseolina (Fungus) Resistant and Glufosinate (Herbicide) Tolerant Transgenic Jute

“…Along with many other adverse factors, the cost of cultivation increases when jute fields need management to alleviate infestation of weeds, fungi and insects. Protection from devastating Lepidoptera, that devour jute plants, was achieved when Majumder et al (2018) first developed transgenic Bt-jute and successfully tested it against major insect pests of jute. It assured healthy jute production and fiber quality.…”

“…Agrobacterium mediated shoot tip transformation and in vitro regeneration of explants were done as described by Majumder et al (2018) . Isolated shoot tips were immersed in the Agrobacterium “infiltration/co-cultivation” media [MS salts and vitamins + 0.1% myo-inositol + 2% sucrose + 0.5 mg/l N6-benzylaminopurine (BAP) + 1 mg/l indole-3-acetic acid (IAA) + 0.2 mg/l gibberellic acid (GA 3 ) + 20 mg/l acetosyringone at pH 5.6] for 1 h in dark.…”

“…The qRT-PCR was performed in CFX 96 Real time system ® (Bio-Rad), in triplicates. Jute 26S ribosomal RNA ( 26S rRNA ) gene was used as internal control to normalize all data ( Majumder et al, 2018 ). The qRT-PCR reaction mixture was constituted with specific primers ( Table 1 ), MAXIMA SYBR GREEN ® (Thermo Scientific) and cDNA.…”