Study of polyembryony and development of molecular markers for identification of zygotic and nucellar seedlings in Khasi mandarin (Citrus reticulata Blanco)

Abstract

The objective of this work was to evaluate the occurrence of polyembryonic seedlings and other morphological parameters in Khasi mandarin during three harvest years and to identify zygotic (sexual) seedlings from nucellar (asexual) ones grown under invitro conditions using molecular markers. Embryos from 27 polyembryonic and 7 monoembryonic seeds of Khasi mandarin were grown in-vitro. DNA from seedlings and mother parent was analyzed using 16 ISSR and 5 RAPD primers, of which 4 ISSR and a set of 3 RAPD primers were effective to identify zygotic or nucellar origin of the seedlings. In-vitro culture enables maximum embryos of each seed to grow, favouring the origin of seedlings to be identified as zygotic. Among 69 tested individuals, 37 zygotic and 32 nucellar seedlings were recognized. In polyembryonic and monoembryonic seeds, 59.6% and 42.8% of the seedlings, respectively, have the sexual origin. Morphological characteristics of seeds and the seedlings generated varied significantly and were not correlated with polyembryony except for the clutch size and the number of branches. Polyembryonic seeds in the cultivar are high, ranging from 50.0%, 55.5% to 83.3% over three harvest years with more clutch size and the possibility of obtaining zygotic plants from them is high. In polyembryonic seeds not all zygotic seedlings were produced by small embryos located at the micropyle. Identification of zygotic seedlings by ISSR and RAPD markers in Khasi mandarin cultivar is efficient and reliable at an early developmental stage.

Screening of citrus scion-rootstock combinations for tolerance to water salinity during seedling formation

“…The seeds that had been previously selected and treated with fungicide (4 g of Thiram kg -1 of seeds) were sown in tubes (three per tube) with a capacity of 288 mL in a commercial substrate containing a combination of 1:1:1 vermiculite, pine bark and humus. Only one seedling of nucellar origin was allowed to develop in each container (Kashyap, Banu, Shrivastava, & Ramchiary, 2018). The nucellar seedlings were identified based on the morphological characteristics, particularly the characteristics related to the leaf blade.…”

Morphology of seeds and seedlings, and substrates in germination of Citrus limetta

“…The lower production of clones, that is, only one seedling per seed, in genetical enhancement programs, could be used as female parents in controlled hybridizations and would be advantageous, allowing greater ease in obtaining and selecting the zygotic embryos of interest (DUARTE et al, 2013). KASHyAP et al (2018) affirmed that polyembryony varies according to the ecological region and the cultivar, suggesting that it is specific to each variety in relation to the region. They also affirmed that this does not seem to be a limiting factor in the germination capacity.…”

Cytogenetical Changes among Polyembryonic (PEm) and Non-PEm Maize Plants

“…Various agronomic, genetic and bromatological studies have been carried out on PE, and there are some attempts to associate different morphological traits to polyembryony. It has been mentioned that seed and seedling morphological traits in polyembryony citrus varieties were significantly different and were not correlated with polyembryony except for the clutch size and the number of branches [6]. In addition, it is still unknown whether the polyembryony in maize is the product of chromosomal abnormalities.…”