Cowpea [Vigna unguiculata (L.) Walp.]

Abstract

Agrobacterium tumefaciens-mediated transformation is an efficient method for incorporating genes and recovering stable transgenic plants in cowpea because this method offers several advantages such as the defined integration of transgenes, potentially low copy number, and preferential integration into transcriptional active regions of the chromosome. Cotyledonary node explants of cowpea present an attractive target for T-DNA delivery followed by regeneration of shoots via axillary proliferation without involvement of a de novo regeneration pathway. In this chapter, we describe a detailed protocol for Agrobacterium-mediated transformation of the cowpea variety Pusa Komal. The seedling cotyledonary node explants are used for cocultivation with an Agrobacterium strain EHA105 harboring standard binary vector, pCAMBIA2301 or pNOV2819, and putative transformed plants are selected using aminoglycoside antibiotic or mannose as sole carbon source, respectively. The entire process includes explant infection to transgenic seed generation in greenhouse.

An Improved Transformation System for Cowpea (Vigna unguiculata L. Walp) via Sonication and a Kanamycin-Geneticin Selection Regime

“…These technical changes resulted in a cowpea transformation system with an efficiency of just over 1%, with 73 independent transgenic lines obtained. This rate is similar to, or better than some other cowpea transformation studies in which efficiencies ranged from 0.15 to 3.9% (Popelka et al, 2006; Chaudhury et al, 2007; Ivo et al, 2008; Solleti et al, 2008; Adesoye et al, 2010; Raveendar and Ignacimuthu, 2010; Behura et al, 2015). The sonication of legume cotyledonary nodes has been shown to increase the transformation efficiency.…”

“…Despite several reports over nearly three decades, the genetic engineering of cowpea is still challenging, consistent with the generally recalcitrant nature of legumes to in vitro manipulation (Somers et al, 2003; Bakshi and Sahoo, 2013). This is well illustrated by the many methods that have been trialed using cowpea regeneration via somatic embryogenesis and direct multiple shoot organogenesis (Garcia et al, 1987; Kononowicz et al, 1997; Brar et al, 1999; Popelka et al, 2006; Chaudhury et al, 2007; Raveendar et al, 2009; Behura et al, 2015). Garcia et al (1987) were among the first to attempt transformation experiments in cowpeas using Agrobacterium .…”

Genetic Diversity and Population Structure of Cowpea (Vigna unguiculata L. Walp)

“…Cowpea cereal is a very important source of carbohydrates (63%) and proteins (25%), with low fat content (1.5%), and is rich in vitamins, minerals (Ca, P, Fe), folate, thiamin, and riboflavin. Cowpea is chiefly used as a grain crop; however, it also finds use as animal fodder or as a vegetable [ 1 , 2 ].…”

RNAi-derived transgenic resistance to Mungbean yellow mosaic India virus in cowpea

“…Application of RNAi for trait improvement in cowpea depends on availability of reliable transformation system. Cowpea is highly recalcitrant to genetic transformation and till date, only a few laboratories have succeeded in transforming cowpea [ 59 ]. In the past, we have established efficient Agrobacterium- mediated transformation of cowpea by improving transformation efficiency through the use of extra copies of vir genes [ 60 ], sonication and vacuum infiltration [ 61 ], seedling preconditioning in thidiazuron [ 62 ] and by employing positive selection [ 63 ].…”