Haploid plantlet production in tomato

Abstract

One of the routine problems facing plant breeders is how to rapidly develop inbred lines for either direct release or for use as parents of hybrids. One way to accomplish inbreeding efficiently is to produce haploid or dihaploid plants from pollen or anthers of F₁ hybrids. Although much research has been conducted on tomato (Lycopersicon esculentum Mill.) pollen or anther culture, at least three problems have emerged as roadblocks to the successful application of these techniques. First, because both the number of anthers producing calli and the number of plants regenerated per callus have been limited, few plants have been recovered. Secondly, very few tomato anther genotypes have been evaluated under a variety of experimental conditions to rate their callus forming and regeneration potential. Third, various media/-methods have been used to produce plantlets of unknown ploidy. In many of these systems closer evaluation suggests that plantlets developed as a product of organogenesis from anther wall tissue rather than via androgenesis (Zamir et al., 1981). This chapter reviews published reports of tomato anther and microspore culture, contrasts procedures that produce anther-derived calli and plantlets (Fig. 1) with those that do not, and explores factors that need optimization or further study prior to routine haploid plantlet production via anther and/or microspore culture.