Male Sterility in Pea II. Male sex specific dys-synapsis.

Abstract

Dys-synapsis, involving lack or impaired synaptic pairing, confined only to the male sex was detected in a 0.05% DES induced mutant of Pisum sativum variety Arkel. This anomaly is controlled by a single nuclear recessive gene msg4, non-allelic to the other msg genes isolated in P. sativum genome. The synaptic anomaly leads to abnormal male meiosis involving premature chiasmata terminalization, nucleolar multiplication, univalency, unequal and ir-regular chromosome disjunction at AI and AII, unequal triads and tetrads and coenocyth formations. This result in degenerated microspore formation rendering the mutant tota male sterile.The meiotic anomalies exhibit high proportion of variance and the initial anomalies add to the variance of the subsequent abnormalities making male meiosis exceedingly erratic. The major meiotic anomalies are inter-correlated but only some exhibit genetic correlations whicl unravel causes and consequences of meiotic anomalies detected in this mutant. The dys gene causing the male sex specific anomalies, does not belong to the gene system regulating chiasma formation and its terminalization in P. sativum. Instead, it is a special gene disrupting male meiosis only and is anther specific.