Screening of Mango Landraces for Polyembryony and Confirmation of Seedling Origin using Microsatellite Markers

Abstract

Background: The introduction of polyembryonic rootstocks in the area of propagation is of great importance since they produce one zygotic and several nucellar plantlets. Proper identification of sexual embryo from each hybrid seed is necessary in order to preserve only the nucellar seedlings, which would help to maintain the rootstock’s genetic characteristics as well as to overcome the major constraints in the area of fruit breeding especially in hybridization programme by eliminating the nucellar ones to advanced generations. Contrasting reports exists regarding the vigour of zygotic seedlings of polyembryonic mango genotypes. It is necessary to identify/ distinguish the zygotic seedling from the nucellar population at an early stage, for which, microsatellite analysis could be a reliable tool. Methods: The experiment was laid out in completely randomized design (CRD) with 20 treatments replicated thrice. The twenty local mango landraces from Thiruvananthapuram (Kerala) were screened for polyembryony and were geo-referenced. Germination studies were conducted. Microsatellite analysis of all the plantlets from two varieties which exhibited the highest polyembryony were done using SSR primers and their banding patterns were compared with those of their respective mother plants. Result: Out of twenty mango varieties screened, seventeen were polyembryonic. Kappa Manga recorded the highest germination, germination index and seedling vigour index-I. Kotookonam Varikka recorded the highest polyembryony and followed by Kochu Kilichundan. Microsatellite analysis revealed that all the seedlings obtained from the respective stones of Kotookonam Varikka and Kochu Kilichundan had identical SSR profile to the mother plant, which indicated nucellar origin of seedlings having similar genetic composition to the mother plant.