Effects of 2, 4- Dichlorophenoxyacetic Acid and 2, 3, 5 - Triiodobenzoic Acid on Callus Induction of Selected Maize (Zea mays L.) Genotypes

Abstract

Maize (Zea mays L.) anther culture is a promising technique for rapid doubled haploid production, but its efficiency is constrained by genotype dependency and low callus induction rates. This study aimed to (1) evaluate the effects of various concentrations and combinations of 2,4-Dichlorophenoxyacetic acid (2,4-D) with kinetin or Naphthaleneacetic acid (NAA), and 2,3,5-triiodobenzoic acid (TIBA) alone on callus induction across five maize genotypes commonly used in Myanmar’s breeding programs, and (2) assess genotypic differences in androgenic response. An experimental approach was employed using Murashige and Skoog (MS) media supplemented with varying concentrations and combinations of 2,4-D plus kinetin or NAA, and TIBA alone. Callus formation was monitored over eight weeks, and data were analyzed to determine the influence of plant growth regulators (PGRs) and genotype on induction rates. Significant differences were observed among genotypes and PGR treatments, with Yezin 14, C7, and D6 exhibiting the highest frequency of late uninucleate microspores and superior callus induction. The combination of 2,4-D (2.0 mg L⁻¹) plus kinetin (1.5 mg L⁻¹) produced the highest callus induction rate of 19.44% in Yezin 14. TIBA, when used alone, also stimulated callus formation, although it often resulted in increased watery callus. Chi-square analysis confirmed that both genotype and PGR treatment significantly influenced callus induction efficiency (p < 0.05). Therefore, the optimization of these factors—genotype,and plant growth regulators—is essential for improving the efficiency and reproducibility of maize anther culture protocols.These findings highlight the importance of optimizing genotype-specific protocols and the balance of hormones to enhance androgenesis in maize. The results provide valuable insights for improving doubled haploid production in Myanmar’s maize breeding programs, contributing to more efficient and rapid cultivar development. Future research focusing on refining hormone combinations and exploring molecular mechanisms underlying genotype-specific responses could further enhance anther culture success, ultimately accelerating maize breeding and contributing to food security.