Correlative controls of senescence and plant death in Arabidopsis thaliana (Brassicaceae)

Abstract

Like most monocarpic plants, longevity of Arabidopsis thaliana plants is controlled by the reproductive structures; however, they appear to work differently from most dicots studied. Neither male- and female-sterility mutations (ms1-1 and bell1, respectively) nor surgical removal of the stems with inflorescences (bolts) at various stages significantly increased the longevity of individual rosette leaves, yet the mutants and treated plants lived 20-50 d longer, measured by the death of the last rosette and/or the last cauline leaf. A series of growth mutations (clv2-4, clv3-2, det3, vam1 enh, and dark green) also increased plant longevity by 20-30 d but did not delay the overall development of the plants. The mutations prolonged plant life through the production of new leaves and stems with inflorescences (bolts) rather than by extending leaf longevity. In growing stems, the newly-formed leaves may induce senescence in the older leaves; however, removal of the younger leaves did not significantly increase the life of the older leaves on the compressed stems of Arabidopsis. Since plants that produce more bolts also live longer, the reproductive load (dry weight) of the bolts did not seem to drive leaf or whole plant senescence here. The developing reproductive structures caused the death of the plant by preventing regeneration of leaves and bolts, which are green and presumably photosynthetic. They also exerted a correlative control (repression) on the development of additional reproductive structures.

Large‐scale identification of leaf senescence‐associated genes

“…Similar differences in expression of some of the senescence-enhanced genes are expected even between related monocarpic plants whose senescence is triggered by different signals. For example, the Columbia ecotype (Col-0) of Arabidopsis, which was also studied in the present research, displays a phenomenon characteristic of many monocarpic plants; removal of ower or bolt increases the longevity of the whole plant (Nooden and Penney, 2001). This correlation suggests a link between reproductive organ development and induction of senescence.…”

“…This correlation suggests a link between reproductive organ development and induction of senescence. However, unlike soybean plants whose leaf senescence is controlled by reproductive structures, male and female sterile mutants and surgical removal of in¯or-escence bolts in Arabidopsis did not increase the longevity of the individual leaves (Nooden and Penney, 2001). Some differences in gene activation related to the induction phase of senescence in various monocarpic species are expected, and comparative genomic studies are required to identify genes related to the induction phase.…”

“…These species may not share identical regulatory pathways. For example, while leaf senescence of several monocarpic species is controlled by¯ower and fruit development, such linkage was not found in Arabidopsis thaliana ecotype Landsberg erecta (Nooden and Penney, 2001). Thus, the information accumulated from different unrelated species may not allow the prediction of an integrated network operating during leaf senescence.…”

Seed Production Affects Maternal Growth and Senescence in Arabidopsis

“…Interestingly, control mechanisms exerted by developing seeds over maternal growth and life span have been observed in plants (Murneek, 1926;Molisch, 1929;Noodén et al, 2003). In legumes such as soybean (Glycine max), for example, both reproductive growth and the onset of leaf senescence are under correlative control (Noodén and Penney, 2001) by developing seeds so that plants grow and live considerably longer when developing fruits are continuously removed (Leopold et al, 1959;Lindoo and Noodén, 1977). Such a pattern is readily found in monocarpic plants (i.e.…”

Yaprak Senesensi: Fizyolojik ve Moleküler Düzenlenmesine Bakış

“…Arabidopsis'in de içinde bulunduğu bir çok bitki türünde dışsal streslerin yokluğunda, yaprak senesensi yaşa bağlı olarak meydana gelebilir. Yabani tip Arabidopsis bitkilerinden ve reprodüktif büyümesi geciktirilmiş (geç çiçeklenme mutantları = lateflowering mutants) ya da bozulmuş (erkek ya da dişi steril mutantlar) mutantlardan alınan bireysel yapraklar aynı ömür uzunluğuna sahiptirler [28].…”