Fine mapping and candidate gene analysis of major QTLs for number of seeds per pod in Arachis hypogaea L.

BACKGROUND

Peanut (Arachis hypogaea L., 2n = 2x = 20) is an important industrial and oil crop that is widely grown in more than 100 countries. In recent years, breeders have focused on increasing the seed number per pod to improve their yield in addition to other breeding for other key components of yield, including the pod number, seeds per pod, and 100-seed weight.

RESULTS

In this study, a secondary population of 1,114 BCF lines was derived from a cross between the parents R45 and JNH3. Two stable major-effect quantitative trait loci of qRMPA09.1 and qRMPA09.2 were detected simultaneously and mapped within chromosomal intervals of approximately 400 Kb and 600 Kb on chromosome A09. Additionally, combined whole-genome and RNA sequencing analyses showed the differential expression of the Arahy.04JNDX gene that belongs to a MYB transcription factor (TF) between the two parents. The AhMYB51 gene was also inferred to influence the number of seeds per pod in peanuts. An examination of the backcross lines L/L showed that AhMYB51 increases the rate of multiple pods per plant (RMSP) primarily by affecting brassinosteroids in the flowers, while its overexpression promotes the length of siliques in Arabidopsis thaliana.

CONCLUSIONS

Our findings provide valuable insights for the cloning of favorable alleles for RMSP in peanuts. The qRMSPA09.1 and qRMSPA09.2 are two novel QTL associated with the RMSP trait, with AhMYB51 predicted as its candidate gene. Moreover, the closely linked polymorphic SNP markers for loci of two significant QTLs may be useful in accelerating marker-assisted breeding in peanuts.