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Internode length and anatomical changes in Pisum genotypes cry s and cry c in response to extended daylength and applied gibberellin A 1
Author(s) -
Murfet Ian C.
Publication year - 1990
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1990.tb02109.x
Subject(s) - pisum , gibberellin , photoperiodism , plant stem , biology , sativum , botany , horticulture , elongation , materials science , metallurgy , ultimate tensile strength
Dwarf pea ( Pisum sativum L.) plants with genotypes cry c and cry s responded differently when an 8 h photoperiod (8 h daylight, 16 h dark) was extended to 24 h (8 h daylight, 16 h incandescent light). Genotype cry c showed up to a 4‐fold increase in internode length, sustained by increases in both cell length (particularly of epidermal cells) and cell number (particularly of cortical cells) while cry s plants showed up to a 2‐fold increase in internode length sustained mostly by an increase in cell number. Under an 8 h (daylight) photoperiod the two genotypes did not differ in their sensitivity to applied gibberellin A 1 (GA 1 ) and they showed a similar pattern of response. GA 1 significantly increased internode length, cell length and cell number in both genotypes. Incandescent light did not increase the size of the response to GA 1 except for cry s plants at high dose rates of GA 1 (29–58 nmol). At saturating doses of GA 1 the two genotypes attained a similar peak internode length; incandescent light increased the peak by about 40%. GA 1 increased the rate of leaf appearance by up to 33% while incandescent light reduced the rate by 4–7%. The elongation response of the more mature internodes of cry c plants to GA 1 or incandescent light was due primarily to an increase in cell length whereas increased cell number made a significant contribution in the case of internodes which were relatively immature at the time the stimulus was applied. The progressive increase in internode length of both genotypes during ontogeny was due primarily to an increase in cell number. In conclusion, alleles cry c and cry s (background le La ) do not confer a difference in sensitivity to GA 1 and the increase in internode length in response to incandescent light is probably not the result of a real or perceived increase in GA 1 level. Allele cry s may partially block a phytochrome mediated response to light and the key difference between genotypes cry s and cry c may lie in the greater elongation (extensibility?) of cry c epidermal cells in incandescent light.