Ethylene Production by Attached Leaves or Intact Shoots of Tobacco Cultivars Differing in Their Speed of Yellowing during Curing

Abstract

Using an open air flow system, differences in the yellowing rate of leaves during curing were assessed in relation to ethylene production by shoots of intact seedlings or attached mature leaves of 60 day old tobacco (Nicotiana tabaum L.) plants. The rate of ethylene evolution from the leaves of the fast yellowing cultivars was significantly higher than in the slow yellowing ones. The same differences were obtained with shoots of intact seedlings. The findings suggest that it is possible to use ethylene production by seedlings as a selection criterion in screening for genotypic differences in the rate of yellowing. The (e.g. 3, 4, 17). An open continuous flow system for detection of ethylene was developed in this laboratory (5, 12), and it has been used with both intact shoots and excised segments of leaves or seedlings (7). It was found that intact shoots of sunflower, soybean and tomato seedlings in a flow-through open system produce less ethylene than the corresponding excised leaf segments in a closed system (7). To date, there has been no report on ethylene measurements from single attached leaves incubated in an open system. In the present work, shoots or single leaves of intact plants were used for measurements of ethylene production.It is known that C02 affects the rate of ethylene evolution from tissues (6,11,16), presumably acting on the conversion of ACC4 to ethylene (16,19). However, there has been no report on the effect of CO2 on the possible differences in ethylene production among tissues at different stages of development. This paper also reports on the C02-induced ethylene production in relation to the previously mentioned tobacco varietal differences. MATERIALS AND METHODSThe attainment of a bright yellow color is important for the marketability oftobacco. Curing accelerates yellowing and many other aspects of senescence typical of detached leaves. Reduction of curing time is economically important. Ethylene and ethylene releasing chemicals have been used to attain a bright yellow color and reduce curing time of tobacco leaves (1). The time required for yellowing during flue-curing differs among Philippine tobacco cultivars, ranging from 35 to 60 h (15). This study assesses the possible relationship between rates of ethylene production in tobacco leaves and the known speeds of yellowing of the leaves during flue-curing.The role of ethylene as an initiator of senescence is well documented for flowers and fruits (1,4,18,20), but evidence for a similar role in foliar senescence is lacking (14,20,21). Although some workers propose that a rise in ethylene production triggers senescence in leaves (4,13,17,18) Plant Material and Culture. Four cultivars of tobacco (Nicotiana tabacum L.) were used in this study, Coker 86, WR-5, Coker 258, and NCBY, certified seeds of which were obtained from the Philippine Tobacco Research and Training Center, Ilocos Norte, Philippines. The first two cultivars exhibit a slow yellowing (SY) behavior during flue-curing and the latter two are fast yellowing (FY)...

The climacteric-like behaviour of young, mature and wounded citrus leaves

“…Several reports have demonstrated that ethylene production in attached or detached leaves of various species increased during senescence or in response to exogenous ethylene in a climacteric-like pattern (Aharoni et al, 1979;Alejar et al, 1988;McGlasson et al, 1975;Morgan and Durham, 1980;Gepstein and Thimann, 1981;Riov and Yang, 1982;Morgan et al, 1992). A similar phenomenon was observed in leaf discs following wounding and particularly in response to ethylene treatment (Aharoni et al, 1979;Riov and Yang, 1982).…”

“…In general, leaves evolve increased levels of ethylene during natural senescence as they do after detachment (Aharoni et al, 1979;Alejar et al, 1988;McGlasson et al, 1975;Morgan and Durham, 1980;Gepstein and Thimann, Fig. 4.…”

Physiological and biochemical changes in shoots of coconut palms affected by lethal yellowing

“…Abscission of fruits can be promoted by ethylene (Sexton et al, 1985;Henderson & Osborne, 1994) and it is well documented that stomatal closure can be induced by ABA (Jones & Mansfield, 1970;Zhang, Schurr & Davies, 1987;Davies & Jones, 1991). Leaf senescence can be promoted by ethylene (Alejar, Viser & Spencer, 1988;Matoo & Aharoni, 1988;Aharoni, 1989) and ABA (Nooden, 1988).…”

Different yellowing degrees and the industrial utilization of flue-cured tobacco leaves

“…Multiple factors influence industrial utilization and the style of the tobacco leaf and include the ecological environment, cultivar, maturity, agronomic management, and curing technology (Reed et al, 2012). Among these factors, the yellowing stage in the flue-curing process is a key step during which complex physical, physiological, and biochemical reactions materialize in the tobacco leaves (Bacon et al, 1952;Weston, 1968;Koiwai and Kisaki, 1979;Alejar et al, 1988). Previous studies have focused on various aspects of the curing process for flue-cured tobacco leaves, including temperature, humidity, time, and draft fan control (Zhan et al, 2011;Cui et al, 2013;Xie et al, 2013).…”