Introducing linked primers for apple (Malus pumila Mill) flowering or vegetative buds using cDNA-based expression

Abstract

The juvenile period in trees may keep breeders from the early achievement of successive generations in fruit tree breeding. Shortening this period could lead the plant breeders to improve fruit production faster. The objective of the current research was to identify the candidate loci or primers for apple flower and vegetative (leaf) buds using the cDNA-RAPD technique. Leaf and flower buds were collected from Red and Golden Delicious apples. The synthesized cDNAs were amplified using the cDNA-RAPD based gene expression technique by 10 RAPD primers. All the primers were polymorphic, with an average of 6.2 bands and an average PIC value of 0.162. The highest number of polymorphic bands belonged to the Ah1 primer (11 bands). Marker index (MI) was obtained between 0.702 for Ah6 primer, and 1.32 for Ah1, implying a higher efficiency of the Ah1 primer in determining polymorphisms. Ah3 and Ah4 were more efficient in this respect than the other examined primers. Binary logistic and cluster analyses results showed that the ALL3-Ah1 (815-820 bp), ALL11-Ah1 (740-750 bp), ALL40-Ah7 (885-900 bp), ALL41-Ah7 (800 bp), and ALL45-Ah8 (790-800 bp) bands (alleles) have a significant association with the flower buds, and the ALL44-Ah8 (700-710 bop) allele with the vegetative buds. The identified alleles could be further sequenced and utilized to induce flowering in apple trees. They could be considered as the primers linked to the flowering or vegetative control loci. These primers may serve as selection criteria in the molecular breeding of flowering or vegetative states in apple. It provides a foundation for future studies toward the determination of the functional importance of these candidate loci for shortening the juvenile period of the apple trees. They can be utilized for genetic transformation to induce flowering and shorten the juvenile period in apples and similar trees.