Use of chemical mutagens for production of inactive pollen grains, embryo rescue, and morphological changes in cucumber

Abstract

Application of chemical mutagens as important factors is very practical for successful haploidization techniques inCucurbitaceae through pollen grain deactivation and then immature embryo rescue. The present research investigated the effects ofgenotype, male flower age, receptor plant, and chemical mutagenesis ($NaN_3$ and colchicine) on pollen grain deactivation as well asseed production (number of total, full, half-full, and empty seeds) and morphological traits. Moreover, the effects of different plantgrowth regulators were tested on embryo cultures. The effects of different factors (mutagen, genotype, flower age) were investigated onplant regeneration from immature embryos that were inspected from half-full and empty seeds. Based on this study, some mutagenictreatments (0.005 colchicine and 0.0012 $NaN_3$) led to the highest values of morphological and fruit yield traits in control plants, while0.005 and 0.025 $NaN_3$ led to reduced values of these traits. Among the genotypes, NBDC3 showed the highest number of differenttypes of seeds. Among different chemical mutagens, $NaN_3$ (0.0012 mg/L) and colchicine (0.005 mg/L) produced the greatest effectson seed production traits. Moreover, the highest values for all seed-related traits were recorded for crossing with fresh male flowers,whereas crossing with old male flowers contributed to the decline of seed-related traits. Mutagen-treated plants showed the highestempty seed numbers. Furthermore, the highest total and half-full seed numbers were obtained using 0.0012 and 0.005 mg/L $NaN_3$ andcolchicine. Results revealed that the highest and lowest regeneration percentages (66.67% and 26.67%) belonged to the media containingBAP+Kin+IBA (2+1+0.5) mg/L and BAP+Kin+IBA+NAA (2+1+0.5+0.1) mg/L, respectively. These media were used for immatureembryo culture. Finally, genotypes NBDC1 and NBDC3 treated with 0.005 colchicine and 0.012 NaN3 showed higher frequencies ofplant regeneration from immature embryos extracted from half-full and empty seeds.