New liguleless (lg2) maize stocks: Genetic resources for leaf architectural and haploid induction rate assessment studies

Liguleless mutants produce defective ligules and auricles and, consequently, have more upright leaves than their ligulate counterparts, making them useful genetic material for plant architectural studies. Besides, owing to the recessive nature and amenability of the liguleless trait to phenotyping at the seedling stage, liguleless mutants are popularly used for 'proof-of-concept' demonstration and assessment of haploid induction rate (HIR) of haploid inducer lines (HILs) in maize. The commonly used liguleless testers in maize are of temperate origin and are challenging to use and maintain under tropical/sub-tropical conditions. In the present study, liguleless lines (V 601, V 602, V 603 and V 604) derived from crosses between agronomically superior locally adapted tropical ligulate lines (V 407 and CM 152) and liguleless donors of temperate origin (PDH-3 and PDH-8) were evaluated for different agro-morphological traits. Liguleless line V 602 was also used as a tester to assess the HIR of haploid inducer line EC937890 (CIM2GTAILP2). The results showed a mean HIR of 12.42% for EC937890, consistent with the HIR reported in other studies, thus demonstrating the efficacy of V 602 as a tester for determining HIR. The agronomically superior liguleless maize lines reported in this study will, therefore, be a valuable resource for leaf architectural studies, assessment of HIR of candidate HILs and maintenance of high HIR in the HILs presently in wide use in the doubled haploid (DH) programmes. Additionally, these genetic stocks carry the liguleless trait in genetic backgrounds with known heterotic affinity with early maturity Indian public maize germplasm and, therefore, can be used directly as parents in hybrid development programmes.

Automated summary

Liguleless mutants are useful for plant architectural studies and assessment of haploid induction rate in maize. In this study, liguleless lines derived from crosses between locally adapted tropical ligulate lines and liguleless donors of temperate origin were evaluated for different agro-morphological traits. Liguleless line V 602 was also used as a tester for assessing the haploid induction rate of a haploid inducer line. The results showed the effectiveness of V 602 as a tester and the value of the liguleless maize lines for leaf architectural studies and maintenance of high haploid induction rate.