Effects of nuclear and cytoplasmic genes altering chlorophyll loss on gas exchange during monocarpic senescence in soybean [Glycine max]

• Published in: Plant and cell physiology 1990, Vol.31 (8), p.1123-1130
• Main Authors: Guiamet, J.J. (University of Michigan, Ann Arbor (USA)), Teeri, J.A, Nooden, L.D
• Format: Article
• Language: English
• Subjects: Abscission; Biological and medical sciences; CHLOROPHYLLE; CHLOROPHYLLS; CLOROFILAS; CYTOPLASMIC INHERITANCE; ECHANGE GAZEUX; Fundamental and applied biological sciences. Psychology; GAS EXCHANGE; GENE; GENES; GLYCINE MAX; HEREDITE CYTOPLASMIQUE; HERENCIA CITOPLASMATICA; INTERCAMBIO DE GASES; Photosynthesis; Plant physiology and development; Senescence; Senescence and abscission; Transpiration; Vegetative apparatus, growth and morphogenesis. Senescence
• ISSN: 0032-0781; 1471-9053; 1471-9053
• DOI: 10.1093/oxfordjournals.pcp.a078025

Several genes can alter the yellowing processes that normally occur during pod development and monocarpic senescence in soybean. CytG and d1 + d2 cause the leaves and seeds to stay green at maturity. G blocks yellowing of the seed coat but not the leaves or embryos. By contrast, another gene, y3, causes earlier yellowing of the leaves. This paper examines the effects of these genes on photosynthesis and some related parameters of the senescence syndrome in near-isogenic backgrounds (cv. Clark). Neither cytG nor d1 d2 delays the decline in photosynthetic rate during monocarpic senescence relative to Clark; while Gd1 d2 does. Again, y3 causes an earlier decrease. Similarly, neither cytG nor d1 d2 alters the decline in stomatal conductance and transpiration, which occurs at the end of podfill; however, Gd1 d2 delays it and y3 advances it. Neither cytG nor d1 d2 prevents the rise in intercellular CO2 during podfill, while Gd1 d2 does, and y3promotes it. These changes in intercellular CO2 may reciprocally reflect the status (maintenance for Gd1 d2 and early loss for y3) of the photosynthetic enzymes. Gd1 d2, d1 d2 and cytG do not appreciably affect leaf blade abscission; however, y3 prevents it. Gd1 d2 increases the dry weight seed yield, and y3 decreases it. Gd1 d2 inhibits several components in the senescence process, while cytG seems to affect mainly chlorophyll loss and y3 may act more broadly than just accelerating senescence. Clearly, the stay-green trait can be caused by more than one genetic locus, and it may or may not maintain photosynthesis.