Split-seed: a new tool for maize researchers

Abstract

Until recently, immature embryos have been a choice tissue for manipulation in culture for regeneration and production of transgenic maize plants. The utility of this explant has been compromised by low output, genotype dependence and time-consuming incubation in tissue culture. We have developed a new explant, the split-seed, which addresses these limitations by formally treating each seed as though it were a "dicot". By splitting maize seed longitudinally, three different tissues: the scutellum, the coleoptilar-ring and the shoot apical meristems are simultaneously exposed. The cells of these tissues can be made competent to enhance the regeneration, given that the molecular networks resulting from exposure of the split-seed to hormones is likely to be different from whole seed and, in turn, affects the in vitro response. Using this explant, callus induction frequency exceeded 92% and the regeneration frequency was 76%. The mean number of shoots regenerated via callus was 11 shoots per callus clump and 28 shoots per explant at first sub-culture. All of the regenerated plants survived and were 95% fertile. The large numbers of fertile plants produced were regenerated in 6-8 weeks. Finally, the incidence of regenerated plants varies as a function of growth regulator profile.

Somatic embryogenesis and plant regeneration of tropical maize genotypes

“…Indeed, regeneration and transformation in tropical and temperate maize have been achieved by both organogenesis and somatic embryogenesis (O'Connor-Sánchez et al 2002;Sairam et al 2003;Al-Abed et al 2006;Valdez-Ortiz et al 2007). T0 shoots regenerated from somatic embryos are usually clonal because these origininated from single somatic cells as compared to T0 shoots regenerated through organogenesis that are often chimeric because of a multicellular origin.…”

Generation of Transgenic Maize by Two Germinating Seed Transformation Methods

“…An optimal depth should be penetrating through the seed coat until the growing point of the embryo was slightly wounded (Al-Abed et al, 2006) whilst minimizing the damage to other tissues. When puncturing an embryo, the three puncture needles were fixed by a piece of rubber and mini holes were made in the growing point region, which might increase the likelihood of exposing the embryo meristematic cells and improve transformation efficiency.…”

“…In their efforts to improve plant transformation techniques, the researchers continued to attempt transformation studies using various in vivo (on planta) tissues and organs, such as the shoot apex, apical meristems and mature seeds (Chen and Dale, 1992;Sticklen and Oraby, 2005;Al-Abed et al, 2006;Risacher and Craze, 2012). These strategies are simple, time-and labor-effective and genotype-independent since they do not depend on tissue culture procedures.…”

Callus induction and plant regeneration from immature zygotic embryos of various maize genotypes (Zea mays L.)

“…옥수수 미성 숙 배로부터 식물체 재분화가 Green and Philips (1975)에 의 해 처음 보고된 이후로 다양한 품종의 미성숙 배로부터 식 물체 재분화 연구가 지속적으로 보고되었다 (Armstrong and Green 1985;Duncan et al 1985;Songstad et al 1988;Bohorova et al 1995;Carvalho et al 1997;El-Itriby et al 2003;Wang et al 2007;Binott et al 2008;Ombori et al 2008;Rakshit et al 2010;Anami et al 2010;De-yi et al 2011;González et al 2012;Ali et al 2014). 미성숙 배 외에도 성숙 배 (Wang 1987;Huang and Wei 2004;Al-Abed et al 2006;Abebe et al 2008;Jia et al 2008;Zhao et al 2008), 중배축(mesocotyl) 조직 (Torne et al 1980), 약 (Ting et al 1981), 유묘의 마디부분 (Santos et al 1984;Sidorov et al 2006), 잎 (Conger et al 1987;Ahmadabadi et al 2007), 영 (glume) (Suprasanna et al 1986), 화서(미성숙 tassel과 ears) 절 단 조직 (Pareddy and Petolino 1990;Songstad et al 1992), shoot-tip 분열 조직 (Li et al 2004)에서 캘러스 형성 및 식물체 재분화가 이루어졌다. 이렇게 옥수수의 여러 다양한 조직 으로부터 식물체 재분화가 이루어졌으나 지금까지 미성숙 배를 사용하였을 때 재분화 효율이 가장 높은 것으로 알려 져 왔다.…”