Microspore selection and in vitro callus induction in maize anther culture

Abstract

Productions of doubled haploid (DH) maize involve development of haploid through in vitro or in vivo technique, and convert to diploid by doubling the chromosomes using chemical agents. DH enables fixation of hybrid vigour of F1 plants. Several temperate seed production companies develop DH maize, and use them as a parent material to develop superior maize hybrids. DH helps to eliminate the presence of lethal alleles, and fixation of hybrid vigour for several generations. Presently two strategies are available for the development of DH lines in maize. The first strategy involves the crossing of maize with special donor parent called inducer lines which results increased occurrence of spontaneous haploids grown in vivo in the field. With the aid of marker capable to express only in haploids the haploids are directly identified in the field and used to develop doubled haploids. In the second strategy haploid microspores from immature anthers or ovules are collected and grown under in vitro condition by tissue culture and the haploids are used to develop DH lines. The in vivo strategy is easier way to produce haploids, but possess limitation of unavailable inducer lines suitable for tropical regions to induce haploids. The in vitro anther culture is a viable strategy to develop haploids in tropical regions. It is necessary to optimize a slightly modified plant tissue culture protocol for in vitro anther culture suitable to specific genotypes and different agro climatic regions. The present report showed the morphometric attributes and selection of immature anthers for haploid production in TNAU maize hybrid COH (M)6. In addition the modified media compositions are optimized for the induction of callus suitable for tropical region.