The Heritability of Abscisic Acid Accumulation in Water-stressed Leaves of Pearl Millet [Pennisetum americanum (L.) Leeke

Abstract

Using detached leaves, two cultivars of pearl millet [Pennisetum americanum (L.) Leeke], B282 and Serere 39, were assessed for variation in the capacity to accumulate ABA in response to water stress. Significant differences in ABA accumulation were detected between cultivars and between different inbred lines within a cultivar, but within lines there was much less variation in this character. In crosses between individual lines of B282 (low ABA) and Serere 39 (high ABA), ABA accumulation in the F1 was mid-way between parental values, indicating additive genetic control and lack of dominance. Selfed progeny of a B282 × Serere 39 cross were selected for contrasting ABA accumulation in the F2 to F4 generations. A sixfold range in ABA accumulation was found amongst 207 F2 progeny. This increased to nearly ninefold at F3 and F4. Regression analysis indicated high heritability of ABA accumulation and rapid approach to homozygosity. As the cross studied involved a dwarf (B282) and a tall (Serere 39) parent, segregation occurred for height as well as for ABA, though not entirely independently. Tall F3 progeny had significantly higher ABA contents than dwarf progeny and high ABA was therefore associated with other traits (e.g. large leaves, high leaf per cent d. wt) characteristic of tall plants. Nevertheless, there was a substantial range of ABA content within both groups which was uncorrelated with height and other characters. The potential use of the selections in studies on drought response is briefly discussed.