Identification of zygotic and nucellar seedling of Harumanis mango through molecular markers and morphological approach

Abstract

Identification of zygotic and nucellar seedlings of Harumanis mango by morphological approach is impossible or hard to be performed. Therefore, this research were to identify zygotic or nucellar seedlings from Harumanis mango polyembryonic seeds through simple sequence repeat (SSR) molecular markers in relation with germination sequence and vigour of seedlings for source of true-totype cutting material. The results showed that there were 3 seedlings per seed on average. The result from the molecular analysis of 136 seedlings (45 seeds) showed four zygotic seedlings in seeds 1, 15, 29 and 43 representing 8.9% of seeds evaluated. Most of the zygotic seedlings were found towards the end of germination sequence except for seed number 15 and the rest were considered as nucellar seedlings. Based on the fitted logistic regression, the predicted sequence to obtain 90% nucellar seedlings is 5.47. This means that, the germination sequence of less than 6 has 90% chance of getting nucellar seedlings compared to zygotic seedlings. Morphological characters such as number of leaves, stem diameter and leaf area could also be used as references with germination sequence. The results showed that there were significant (p<0.01) relationships between germination sequence and all the growth variables. All growth variables were negatively correlated with germination sequence. This suggested that in order to have 90% chances of getting nucellar seedling (germination sequence below 6), the seedling needs to exhibit several morphology characters; big stem girth, tall plant, high leaf number and large leaf area. Therefore, choosing vigour seedling will increase chances of getting nucellar seedlings, which can be used as cutting source for true-to-type planting material or for breeding purposes.