High-frequency plant regeneration through callus initiation from mature embryos of maize ( Zea Mays L.)

Abstract

An efficient maize regeneration system was developed using mature embryos. Embryos were removed from surface-sterilized mature seeds and sliced into halves. They were used as explants to initiate callus on induction medium supplemented with 4.0 mg l(-1) 2,4-dichlorophenoxyacetic acid (2,4-D). The induction frequency of primary calli was over 90% for all inbred lines tested. The primary calli were then transferred onto subculture medium supplemented with 2.0 mg l(-1) 2,4-D. Following two biweekly subcultures, embryogenic calli were formed. Inclusion of a low concentration (0.2 mg l(-1)) of 6-benzylaminopurine (BA) in the subculture medium significantly promoted the formation of embryogenic callus. The addition of silver nitrate (10 mg l(-1)) also supported an increased frequency of embryogenesis. The embryogenic callus readily formed plantlets on regeneration medium supplemented with 0.5 mg l(-1) BA. The regenerated plantlets were transferred to half-strength Murashige and Skoog medium supplemented with 0.6 mg l(-1) indole-3-butyric acid to develop healthy roots. The regenerated plantlets were successful on transfer to soil and set seed. Using this system, plantlets were regenerated from seven elite maize inbred lines. The frequency of forming green shoots ranged from 19.8% to 32.4%. This efficient regeneration system provides a solid basis for genetic transformation of maize.

An efficient and rapid regeneration via multiple shoot induction from mature seed derived embryogenic and organogenic callus of Indian maize (Zea maysL.)

“…The difficulties of using immature embryos are unavailability of explants round the year, seasonal variation for pollination and also the requirement of high quality greenhouse facility. In addition to regeneration response is genotype dependent multiple reports consensus that mature embryos are relatively more resistant to respond in vitro micropropagation with respect to immature embryos 9 , 27 . Maize genotypes have variable differences for in vitro culture 23 and only a few maize genotypes possess regeneration capacity.…”

“…Green and Philips 4 have first reported regeneration from immature embryos of maize. Since then, maize regeneration has been reported from immature embryos, 5 - 8 mature embryos, 9 , 10 nodal regions, 11 leaf tissues, 12 , 13 anthers, 14 , 15 tassel and ear meristems, 16 protoplast, 17 and shoot meristems 18 . To the best of our knowledge, almost all the previously reported protocols were developed using the maize model genotype A188 and their hybrid Hi-II (A188 · B73), which are characterized by high frequency of embryogenic callus proliferation and plant regeneration 19 .…”

Effects of plant growth regulators and l-glutamic acid on shoot organogenesis in the halophyte Leymus chinensis (Trin.)

“…In L. chinensis tissue culture, the effect of 2,4-dichlorophenoxyacetic acid (2,4-D) on callus induction has been investigated using media containing N6 salts and vitamins, 5 mg l -1 glutamine, 500 mg l -1 proline and 500 mg l -1 casein hydrolytes (Liu et al 2004). The predominant external stimulus of 2,4-D for the initiation of callus was approved in L. chinensis (Liu et al 2004) and other plant species (Huang and Wei 2004;Sharma et al 2005;Dhandapani et al 2008). The plant regeneration responses were obviously genotypic when cultured on medium supplemented with a combination of kinetin (Kn) and 6-benzyladenine (BA).…”

“…Somatic embryogenesis using mature seeds or leaf base segments as explants has several advantages: mature seeds are easy to handle and available year round in bulk quantities (Huang and Wei 2004); in addition, leaf base segments are easy to obtain sterilely from mature seeds and in bulk quantities like mature seeds. We report here shoot organogenesis in L. chinensis based on the initiation of embryogenic callus from mature seeds and leaf base segments.…”

Moderate desiccation dramatically improves shoot regeneration from maize (Zea mays L.) callus

“…However, using this process to fix genetic traits is time-consuming and an undesirable trait might be introduced into the derived plant if its gene is closely linked to the gene for the trait. Therefore, to facilitate the application of biotechnology to maize improvement, strategies to improve shoot regeneration frequency have been emphasized and are steadily evolving (Huang and Wei 2004;Che et al 2006).…”