A genetic analysis of the number of cells, length of cell, and gibberellic acid sensitivity in sugar beet and their relation to bolting mechanism

Abstract

Three series of full-sib progenies and parental inbred lines or populations were used to study the inheritance of the number of cells and length of cell along the hypocotyl length, and the response to gibberellic acid in young plants of sugar beet. Variance components were determined by using a factorial cross design. There were no significant estimates of non-additive genetic variation for either cellular characters. Both additive and non-additive genetic variance were responsible for the variability of stem length after GA3 treatment. It is concluded that additive type genes predominantly control the number of cells in all series. The length of cell had significant additive variances in most cases, but it was indeed markedly influenced by environmental factors. Number of cells (cell division rate) and GA3 sensitivity in young plants even before vernalization were related to bolting tendency. Bolting-susceptible genotypes generally expressed higher stem length in the response to added GA3 as compared to the bolting-resistant genotypes. However, some genotypes bolted easily in the field but reacted weakly to the GA3 treatment and vise versa. Genotypes that were susceptible to bolting and/or sensitive to GA3 had a specific range (intermediate) of cell number. There were, however, some genotypes containing an intermediate number of cells which demonstrated low bolting. These responded faintly to gibberellin treatment. The results suggest that several physiological requirements have to be fulfilled before bolting can occur, and that other plant characters interfere with the bolting phenomenon.

Development of new quantitative physiological and molecular breeding parameters based on the sugar-beet vernalization intensity model

“…This genetic potential presents an avenue for advancement in VR through conventional breeding which, unlike genetic modification (GM) approaches suggested by, for example, Pin et al . (2010), are likely to target the multiple genes involved in controlling this quantitative trait (Sadeghian et al 1993).…”

“…Clearly, in the current germplasm, there exists the genetic capacity to develop bolting-resistant varieties that could be sown earlier than the current (late March) sowing dates (Jaggard et al 2007). This genetic potential presents an avenue for advancement in VR through conventional breeding which, unlike genetic modification (GM) approaches suggested by, for example, Pin et al (2010), are likely to target the multiple genes involved in controlling this quantitative trait (Sadeghian et al 1993).…”

Bolting and flowering control in sugar beet: relationships and effects of gibberellin, the bolting gene B and vernalization

“…In earlier studies, attempts to investigate the effects of exogenous GA on sugar beet involved complex methods for measuring cell elongation in the shoot apex, and the results were difficult to interpret ( Lexander, 1987 ; Sadeghian et al , 1993 ). Those experiments were conducted in inductive LDs where the effect of GA may have been masked by photoperiod effects.…”

“…Efforts are under way to clone the B -gene locus ( Gaafar et al , 2005 ), identify and map floral transcription factors ( Reeves et al , 2006 ; Chia et al , 2008 ), and establish their relationships with bolting. The role of growth hormones has also been investigated ( Khalil and Reda, 1980 ; Elliott et al , 1986 ; Wittenmayer and Schilling, 1998 ), with gibberellins (GAs) being most extensively studied in this respect ( Garrod, 1974 ; Lenton et al , 1975 ; Lexander, 1987 ; Sadeghian et al , 1993 ). The discovery that GAs could induce flowering in many plant species under otherwise non-inductive conditions ( Zeevaart, 1983 ) generated much interest among sugar beet breeders, who considered the possibility of accelerating breeding by substituting vernalization with GA application.…”

“…The discovery that GAs could induce flowering in many plant species under otherwise non-inductive conditions ( Zeevaart, 1983 ) generated much interest among sugar beet breeders, who considered the possibility of accelerating breeding by substituting vernalization with GA application. However, in non-vernalized sugar beet, exogenous GAs failed to induce any significant bolting or flowering, although they affected cellular growth at the shoot apex ( Sadeghian et al , 1993 ). In sugar beet, GAs are important for reproductive growth ( Radley, 1975 ; Debenham, 1999 ; Sorce et al , 2002 ).…”