Identification of chromosomal regions associated with ear placement and related traits in maize (Zea mays L.)
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
In the present investigation, the genetic studies of ear height and its related traits were carried out by making crosses between two contrasting parents for ear height i.e, AKON40A (high ear placement) and LM23 (low ear placement) during spring 2020. The F1 hybrids were selfed to produce F2 population and backcrossed with both parents to generate BC1.1 and BC1.2 generations. Generation mean analysis was performed on all six generations i.e., P1, P2, F1, F2, BC1.1 and BC1.2 for the traits viz., plant height, ear height, no. of leaves, leaf width, node count, no. of cobs, days to anthesis, days to silking, 75% husk brown and internodal length. The significance of scaling tests for the all traits showed the presence of epistatic interactions. The genetic components revealed the presence of additive gene action, additive × additive and additive × dominance gene interaction for ear height and plant height. The variance due to environment was prevalent in both ear height and plant height. The numbers of factors governing ear height were estimated to be 236.0. Bulk segregant analysis was performed using 284 SSR markers spanning all 10 chromosomes of maize genome. Out of 146 SSR parental polymorphic markers, 9 markers were found to be polymorphic in contrasting bulks. On the basis of segregation analysis of these markers on F2 population linkage map was constructed. Three linkage groups were formed; first and third linkage group i.e., LG1 and LG3, consisted of 2 markers each, while the second linkage group consisted of 5 markers. LG1 spanned 26.9 cM on chromosome 3 while LG2 and LG3 spanned 42.1 and 6.7 cM on chromosome 6 and 7, respectively. In case of ear height, LOD score near 3 was observed on chromosome 6 between marker and phenotypic variance (R2) was 8.5, which revealed that there is a minor QTL between the SSR markers umc1979 and umc2317. On the basis of present study, recurrent selection can be utilized to improve source population for reducing ear placement by accumulating favorable alleles. Improved source population then can be utilized for inbred line development leading to maize hybrids having medium to low ear placement.
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Tejinder Singh (2021). Identification of chromosomal regions associated with ear placement and related traits in maize (Zea mays L.) (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.