|Chung, Sang-Min - UNIVERSITY OF WISCONSIN|
|Fazio, Gennaro - UNIVERSITY OF WISCONSIN|
Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: June 6, 2002
Publication Date: N/A
Technical Abstract: Although chilling temperatures (=12C) can cause significant damage to cucumber (Cucumis sativus L.) plants, the inheritance of chilling injury and its linkage to other genes in cucumber has not been documented. Genetic variation for chilling tolerance exists in cucumber. Therefore, a study was designed in which cucumber lines [susceptible Gy-14 (P1), tolerant 'Chipper' (P2), and tolerant 'Little John' (P3)], and their cross progeny (F1, F2, and BC1) were evaluated to determine the inheritance of chilling injury (first true-leaf stage; 4C for 5.5 hours). Generation mean analyses were performed under the assumption that chilling injury was controlled by nuclear gene(s). However, chi-square tests suggested that a three and a six-parameter model were not adequate for explanation of the inheritance of chilling injury. Exact reciprocal F1 and F2 cross-progeny of P1 x P2 and P1 x P3 matings indicated that the control of chilling injury in cucumber is due to cytoplasmic factor(s). The mean chilling ratings [1(trace)-9(dead)] of progeny comparisons were: F1(P1xP2) = 6.2 vs. F1(P2xP1) = 1.2; F2(P1xP2) = 6.4 vs. F2(P2xP) = 1) = 1.7, and; F2(P1xP3) = 5.8 vs. F2(P3xP1) = 2.2. When the chilling tolerant line was used as the female parent, all F1 and F2 progeny were chilling tolerant. The mitochondria genome of cucumber is paternally transmitted. Therefore, the chilling tolerant trait identified is likely associated with chloroplast genome, which is itself maternally transmitted in cucumber. This is the first genetic demonstration that chilling injury is controlled cytoplasmic genetic factor(s) in a plant species.