Effect of the genotype, developmental stage and medium composition on the response to in vitro culture of immature zygotic embryos from genus Capsicum

Abstract

A new reliable in vitro technique for immature embryos of Capsicum spp. was developed. A collectionof 10 accessions, encompassing the five cultivated species of Capsicum, and four media formulations,combining different levels of sucrose (40 g/L vs. 80 g/L) and MS salts (¿ × MS vs. 1 × MS), were evaluated.In addition, the four main embryo stages (i.e. globular, heart, torpedo, early cotyledonary) were also con-sidered. Thus, almost 2000 embryos were excised, cultured, and evaluated for germination in the presentexperiment. Genotype (G), media composition (M), and developmental stage (S) contributed significantlyto culture efficiency. G × S and S × M interactions were also significant, although their contribution waslower than individual main factors. C. annuum accession Piquillo, C. frutescens B-144 and, particularly, C.pubescens B-61 showed the highest in vitro germination rates, while C. chinense and C. baccatum acces-sions showed, in general, the lowest responses. In most cases, the more advanced the embryo stage thehigher the culture efficiency. However, for the first time in Capsicum globular embryos from most geno-types were germinated in vitro and also relatively high rates were achieved for heart embryos. Finally,the medium with the lowest levels of both sucrose (40 g/L) and MS (¿ × MS) enabled, in most genotypesand stages of development, the highest in vitro germination rates. In fact, this medium allowed rates ofup to 25% in globular embryos. These results provide useful information to those breeders interested onthe applications of embryo culture in Capsicum peppers (e.g. shortening breeding cycles, perhaps rescueof interspecific embryos).