Intra-specific variability in frequency of meiocytes showing partial desynapsis and multivalent formation in underutilized Carissa spinarum L. from Jammu Shivalik, India

Carissa spinarum L., (commonly called Garna) growing widely in Jammu Shivalik, is valued for its fruits having great nutraceutical value. Somatic complement of this species comprises of 22 chromosomes. In the present investigation, 15 populations were analyzed. The pollen viability of plants in different populations ranged from 77 to 93.4%. To determine whether reduced viability revealed by some of the cytotypes is the outcome of anomalies in chromosome pairing, population-wise meiotic behaviour was worked out. Except two populations that consistently had 11 bivalents in the scored pollen mother cells (PMCs) at pro- and metaphase-I, the remaining ones contained few cells with 2–4 univalents along with 10/9 bivalents. Based on varying frequency of cells having univalents, fifteen populations were categorised into four groups i.e. control (all PMCs having bivalents) and those having low frequency (2–4%), moderate frequency (5–9%) and high frequency (10–16%) of cells with univalents. For each population group, the frequency (%) of cells with univalents was matched with its pollen viability. It was observed that control populations possessing all PMCs with 11 bivalents exhibited maximum viability (93.46%) and the other groups having comparatively high (10–16%), moderate (5–9%) and low (2–4%) frequency of cells with univalent, respectively showed low (81.09%), moderate (86.45%) and high (89.80%) percentage pollen viability. Overall, the frequency (%) of cells having univalents and percentage pollen viability showed negative correlation (r = −0.65, p < 0.05). As such, the cytological data presented for the four population groups of C. spinarum indicates that existence of meiocytes with univalents accounts for reduction in gametic fertility.